December 2017 Volume 15 Issue 11
NDT IN OIL & GAS INDUSTRY
DECEMBER 2017 Volume 15 - Issue 11
Vadodara
FACE TO FACE - Dr. Krishnadas Rao, Former Chairman-HAL
17 - Prediction of Mechanical Properties in Tempered Dual Phase Steel through Non-Destructive Magnetic Hysteresis Loop Technique - Pulsed Eddy Currents: Improvements in Overcoming Adverse Effects of Galvanized Steel Weather Jacket - Robotic Inline Inspection and Leak Detection System for Oil and Gas Pipelines - Simplifying Phased Array UT Process with Digital Solutions and Wireless Collaboration - Study of Distortion of Low-Frequency Axisymmetric Ultrasonic L (0, 2) Guided Waves in Pipe Bends and Elbows
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ARTICLES - Inspection of Off-shore Structures using Remotely Operated Vehicles: Planys Experience
45 - Infrared Thermography and its Applications in Refinery
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PRODUCT GALLERY NDT IN OIL & GAS INDUSTRY
54 - International Events Calendar, 2018 - 15th APCNDT 2017 - Brief Report - 1st NDT Seminar, 1979 - Brief Report
59 - Meeting Schedule - NGC/NCB Officers Team
61 62 December 2017
LETTERS
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PRESIDENT "Oil & Gas Sector is one of the six important sectors in India and affects Indian economy to a great extent. As per survey carried out in 2013, India was the fourth largest consumer of Oil & Gas in the world and expected to take over Japan by 2025. There are 19 refineries in Public sector & 3 in private sectors and nearly 25000 KM pipe line for transportation of these products. Assets used as pipelines, floating/fixed platforms, drilling rigs, tanks, vessels, heat exchangers or other equipments within the Oil and Gas industry are complex and have a limited life cycle. Well done NDT is a highly valuable tool that can save both money and time. The conventional and advance NDT technologies and inspection by well trained and qualified personnel can help to extend the life cycle of these assets in a safe and compliant manner.
This issue of JNDE, specially devoted to Oil & Gas sector will certainly be interesting to the NDT professionals working in this field. The other topics such as Basic NDT, information on NDT products, the latest news in the field of NDT and the advertisement by prominent NDT equipment manufactures will also of be great attraction to NDT professionals and industry at large.
I appreciate the great efforts by every member of the editorial board and the supporting staff to try to bring this issue timely for the NDT professionals. I am sure that all the NDT professionals will also appreciate this issue of the NDE Journal."
D.J.VARDE president@isnt.org.in
/ CHIEF EDITOR We kick off with an array of interesting technical papers from the desk of our guest editor, Mr. V.Manoharan, Senior Scientist GE Global Research, Bangalore. My sincere thanks to him. Followed up by an article shared by Planys Technologies on Inspection of Offshore Structures. We will be looking back at some memorable events. Do read through major international events for 2018 listed, that you might want to consider booking a trip to. This is the last issue for 2017 and I would like to close the year with a bit of news that ISNT registered more than 1000 new memberships in current year; including student, corporate & life members. It is interesting how you feel when there is a year's worth of time ahead of you at one moment and when the same year is behind you the very next moment. This is exactly how I felt as I was signing off on the last issue for the year, a year that comes fast to completion. As always, you may provide your feedback on any aspect of our magazine by contacting us at isnt.jnde@gmail.com. I would very much like to hear your thoughts on any part of this editorial, how we can further publicize the magazine's distinctive features and objectives, and ultimately how we can make it more appealing to you, our valued readers.
RAJUL PARIKH Managing Editor secretary@isnt.org.in
DR. KRISHNAN BALASUBRAMANIAM Chief Editor balas@iitm.ac.in
December 2017
LETTERS
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I am very delighted to be part of this special edition of Journal of NDE focusing on Oil & Gas (O & G) Industries. Non-Destructive Evaluation (NDE) plays a major role in ensuring safe operation of plants in O & G and petrochemical Industries. NDE at specific intervals saves cost and time if testing reveals threats and equipment is repaired before shutting down the facility or experiencing a catastrophic failure. Historical NDE data of assets provide insights on how often a component should be inspected, repaired, or replaced. These insights help in proactive maintenance of equipment’s and reducing unplanned shutdown. High temperature, large volume of infrastructure to inspect, inaccessible areas, hazardous environment are some of specific challenges of O & G industries. Industries and technology organizations are making considerable effort to overcome these challenges by investing in technologies such as permanently installed sensors, robotics & automations, digital inspection, data analytics and wireless communication of data. This issue contains technical papers which are good examples of recent technology trends and addressing issues specific to O & G industries. My best wishes and thanks to all authors who have contributed technical papers to this issue of JNDE. V.MANOHARAN Senior Scientist GE Global Research, Bangalore Manoharan.V@ge.com
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December 2017
December 2017
PUNE- AUGUST 2017 - DECEMBER 2017 Ÿ
14th and 15th September 2017- A workshop for last year Engineering Students was arranged by ISNT Pune Chapter at Sharad Institute of Technology, Yedrav, Ichalkaranji which was coordinated by Mr. Sunil Gophan. Mr. Sunil Gophan, Mr. Kalesh Nerurkar and Mr. Brahme were the faculties for theory and practicals.
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5th and 6th August 2017 - ISNT Pune Chapter supported NCB for Examiners workshop for QMSD Implementation, held at Hotel NooryaHometel, Chinchwad, Pune. 25 people representing 9 of the ISNT Chapters attended the workshop. The workshop was well received and appreciated by NCB.
Students at MT Level II Course
Examiners Workshop
MUMBAI - SEPTEMBER 2017 - DECEMBER 2017 Ÿ 16th September 2017 ISNT AGM was conducted at Capers Banquet, Andheri.
Faculties for workshop were Mr. Paritosh Nanekar (UT), Mr. C.M Khade (VT & LT), Mr. J R Hiremath (PT & MT), Mr. D D Joshi (RT) & Mr. Arbind Kumar (ET) Ÿ 22nd and 23rd August 2017 - A two days National Workshop on "Radiation Safety" was conducted at Quality NDT Services, Bhosari, Pune. Shri Bhausaheb Pangare was the Convener for the workshop. About 20 participants attended the workshop. Ÿ 27th September 2017 - AGM of the Chapter was held and new EC was elected. Ÿ 19th August 2017, 6th September 2017, 25th September, 16th October 2017 and 5th November 2017 - EC meetings were held.
Radiation Safety Workshop
At the AGM
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3rd October to 10th October 2017 - Ultrasonic Testing Level-II regular Participants at UT Level II Course course conducted. Shri L.M.Tolani was the course co-ordinator. ( Examination Date: 11th OCT.2017)
30th October 2017 to 3rd November 2017 - NDT for managers course started. Shri L.M.Tolani was the course co-ordinator. Ÿ 6th November to 10th November 2017 - RTFILevel-II course was held. Examination date: 12th November 2017 EC Meeting Ÿ 3rd Nov 2017 - EC Meeting held at ISNT, Mumbai office.
TRIVANDRUM - SEPTEMBER ‘17 - DECEMBER ‘17 2nd August 2017 - First EC meeting of the new committee conducted at Trivandrum hotel. Ÿ 10th August 2017 - Inauguration of first student chapter at Govt. Engineering college Barton Hill, Trivandrum by Chariman, ISNT. Ÿ 17th August 2017 - Inauguration of second student chapter
at College of Engineering Trivandrum by Chairman, ISNT. 26th September 2017 - EC Meeting conducted at Trivandrum hotel. Ÿ 26th October 2017 - Young engineers forum: Technical lecture on “Pyro Devices for Space: Applications & Ndt” by D r. M . N a l l a p e r u m a l , D G M , N D T F, V S S C NDT: Shri Sambamurthy E, NDTF, VSSC at Trivandrum Hotel.
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Shri Levin .G, Chairman, ISNT Trivandrum chapter handing over the ISNT Corporate membership of the institute to the Principal, CET, Trivandrum.
December 2017
Shri Arumugam.M, Vice C h a i r m a n , Tr i v a n d r u m , a t inaugural ceremony of first students chapter at Govt. Engineering College, Trivandrum.
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S h r i . K . R . M o h a n Ananthanarayanan, Vice chairman, ISNT, Trivandrum chapter delivering the lecture in one day workshop on NDT.
Shri Sambamurthy Engula,Scientist, VSSC,Trivandrum delivering talk on “Pyro devices - NDT”
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MANAGER & HEAD OFFICE IN-CHARGE In ISNT since 02-01-2012. Has vast knowledge and experience in Accounts, Taxation & Administration Matters. Managing day to day functioning of Head Ofce, matters connected with statutory compliance, co-ordinates with ISNT chapters and ISNT Chapters and ISNT Ofce bearers, arrangements for Meetings, guiding HO Staff in their respective area of work.
December 2017
ACCOUNTS OFFICER In ISNT since 1-11 2010. In-charge of work connected with Accounts, Preparation of MIS, payment of statutory dues maintenance of accounting records, preparation of monthly income & expenditure statement and matters connected with ISNT membership.
ADMIN OFFICER In ISNT since 23-3-2011. In-charge of work connected with Training and Certication conducted by NCB-ISNT as per the instruction of NCB Ofce Bearers. Takes care of general correspondences and other administration matters of Head Ofce. Assisting accounts ofcer in regular matters.
OFFICE ASSISTANT In ISNT since 4-8-2014. Coordinates with JNDE Executive, correspondence with subscribers and other institution in connection with JNDE journal. Assisting accounts incharge in matters connected with preparation of vouchers, receipts, tabulation of service tax, data entry in tally and other work assigned from time to time.
JNDE EXECUTIVE In ISNT since 17-8-2015. In-charge of corresponding & coordinating with Editors / Authors / Chapters for write ups & managing contents. Sourcing advertisers & handling advertisements. Invoicing, coordinating payments & JNDE related matter with Head Ofce. Laying out, designing nal cover page, editing, proof reading, taking journal for nal print.
June 2017
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Dr.C.G.Krishnadas Dr.C.G.Krishnadas Nair B.Tech Metallurgical Engineering, M.Sc Engineering, Ph.D. Metal Fatigue.
Dr.C.G.Krishnadas Nair, Former Chairman, Hindustan Aeronautics Ltd, Former Vice Chancellor, Mahaveer Academy of Technology and Science University, Raipur is also Founder President of Society of Indian Aerospace Technologies and Industries (SIATI) and Chancellor, Jain University. He is one of the founder members of NDT Society of India, which got merged with ISNDT later.
D
r.C.G.Krishnadas Nair, Former Chairman, Hindustan Aeronautics Ltd, Former Vice Chancellor, Mahaveer Academy of Technology and Science University, Raipur is also the Founder President of Society of Indian Aerospace Technologies and Industries (SIATI) and Chancellor, Jain University. Dr. Nair holds a Ph.D. in Metal Fatigue & M.Sc (Engineering) from the University of Sask, Canada, and is a distinguished Alumni of IIT Madras, with a B.Tech in Metallurgical Engineering. He is one of the founder members of NDT Society of India, which got merged with IINDIE later. He is a technologist and Industry leader of eminence. During his distinguished professional career spanning over 36 years, he has made significant contributions in Engineering Education, Research and Industry Management. He has authored 20 books, edited and published proceedings of many National and International seminars and authored over 200 technical papers in national and international journals and conferences. For his immense contributions, Dr. Nair has been honored with several awards and recognitions; INAE Life Time Achievement Award (2007), IIM Platinum Award (2004), Scope Award for Best Chief Executive and Gold Plaque from Prime Minister of India (2003), National Metallurgist Award (2003), Padmashree from Government of India (2001), Dr. Ambedkar Bharath Shree Award (2001), Rashtriya Ratna Award (2001), Swadeshi Science Puraskara (2000), Indira Gandhi Priyadarshini Award (1997), Omprakash Bhasin Award for Aerospace (1996), Vasvik Research Award (1992), National Award for R&D (1991), FIE Foundation Award (1991), National Aeronautical Prize (1990), National Award for Best Employer of Physically Handicapped and several others. Recently Ministry of Steel and Mines, Government of India, and Indian Institute of Metals, has honoured him with Lifetime Contribution Award in Metallurgy and Material Science (2017). His areas of Interest include Metallurgy and Materials Science, Aerospace Industry, Small Scale Industries, R&D Management, Post Graduate Research & Education, Teaching and Skill Development/Entrepreneurial Development, Industry, Project and Research Management, Materials Testing and Evaluation including NDT. He has been a member of various scientific advisory councils and committees like the Scientific Advisory Committee to the Cabinet, Govt. of India; Research Council, Regional December 2017
Research Laboratory, National Aerospace Laboratories; Governing Council Member, Jawaharlal Nehru Research and Development Center for Aluminium, and Standing Scientific Advisory Committee, Department of Steel and Mines. He has served as president for two leading Professional Associations, viz., President, Aeronautical Society of India, and President, Indian Institute of Metals. He has been a director / member board of several public and private sector corporates. Sir, you have a very enriching career of nearly 5 decades with so many accomplishments. Your longest stint has been at HAL where you joined as an Engineer and rose to the position of the Chairman. Can you give us a brief highlight of that journey and the challenges you encountered as you made it to the top? It is a very long story but let me share some highlights. I joined in the Helicopter Design and Development division initially as a material scientist to help with the definition of the helicopter from a materials perspective - especially various types of aluminum alloys and composites. With that background, we started working on indigenous development of various types of alloys and composite materials which were then being mostly imported into the country. I moved to the Central laboratory which was a Testing Lab and we converted into a Research Lab, got recognition by DST as a Materials and Process Laboratory and incubated a lot of development activities. They were not inventions but were developed elsewhere in the world but you had to pay a lot to get the knowhow or sometimes it was impossible to get it. Thus, we started our indigenization journey. We developed the alloys and got it manufactured from Indian industries like Indian Aluminum, Alloy Steel Plants, Tata Steel, and others. Then we came to Composites and at that time only NAL was doing some research in this field but they were using chopped glass mat and was not aerospace grade. We wanted to substitute the imported glass fibre composites for our Helicopters. We started from the beginning to set up R&D. We went to Pilkington who was making the glass fibre and then it had to be treated and woven into cloth for which we got expertise from textile engineers. Next, we did chemical treatment followed with resin impregnation & certification after creating the entire process and product. We set up our first fibre glass
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plant in HAL enhancing self-reliance and created lot of job opportunities which gave me and my team a lot of satisfaction. It was a good example at that time of converting research into production. When I was in the Lab, we developed the NDT capabilities into a Centre for R&D and Training. Mr. Jayamangal Prasad was in-charge of that under my guidance and we trained and certified nearly 1000+ technicians and engineers in the HAL NDT Centre and developed a lot of NDT techniques for complex aircraft welded structures, sophisticated castings, forgings and composites. Then I joined the corporate office and under the guidance of the Chairman and Chief of Planning and Development set up a Corporate R&D which would cut across the country where we had many different divisions of HAL. That gave me very good exposure and helped me to reach out to all HAL divisions and many R&D labs across the country. That changed my career. From corporate planning I moved to the Management Cadre and rose to be General Manger of HAL Foundry & Forge and HAL Engine division. However, I actively pursued R&D in metallurgy, materials, testing and analysis including NDT in addition to being a professional manager. I progressed to the position of Executive Director, combining aircraft division, engine division, helicopter division and foundry and forge division. That was the time I took initiative in setting up a dedicated space division with support from ISRO to fabricate satellites and launch vehicle structures. The co-operative team work and the achievements were appreciated by HAL’s top management. Considering my interest in metallurgy and materials, HAL allowed me to serve on the Board of prestigious metallurgical industries and research laboratories, Bharat Aluminium Company, National Aluminium Company, Mishra Dhatu Nigam Ltd, Jawaharlal Nehru Centre for Aluminium Research, Defense Metallurgical Lab, National Aerospace Lab to mention a few. When I was in the Foundry division, I suggested to develop titanium alloy compressor blades and super alloy turbine blades for Jet engines, but the management hesitated thinking it was not possible to develop such sophisticated and advanced technological items in India. However, my friends and mentors in DRDO and metallurgical community encouraged and motivated our team and we succeeded in developing these and getting them type certified. Our cost was only about one sixth of what it costed to import. Dhruv, HAL’s Advanced Light Helicopter (ALH) is a great success story in recent history. It was totally designed and built by HAL. It holds the world record for high altitude flying (7 kms above sea level). It can fly over the sea, over deserts and over the high snow-clad mountains in the Himalayan ranges. Several versions of Dhruv have been developed to meet specific needs of Army, Navy, Coast Guard and for passenger service / search and rescue/disaster relief. Advanced technology & lightweight materials have contributed significantly for the successful design of the Advanced Light Helicopter and for Light Combat Aircraft. HAL was the primary partner with DRDO in developing the worlds lightest advanced combat aircraft, Tejas. One major challenge encountered during the development of ALH and LCA was the embargo on materials, equipments and technology imposed after our peaceful but highly misunderstood nuclear experiment ‘Pokhran’. However, HAL along with national
laboratories through their dedicated R & D mitigated the issues and successfully completed the ALH and LCA projects. The stringent demand for Quality and Reliability in the aerospace sector has always been one of the prime motivators for the growth of NDT and Inspection. What are the current unmet needs which the NDT professional should focus on? The ever-increasing demands of structural integrity, safety and multi role capabilities have given rise to new lighter weight materials, engineered materials, such as composites, honeycomb bonded sandwich structures, co-cure co-bonded structures and many advanced processes such as adhesive bonding, isothermal forging, hot iso-static pressing, additive manufacturing (3D printing) and the like. Automation and robotics in manufacturing are becoming extensively used techniques for improving productivity and quality. There has been a continuous pressure on developing NDT technology and techniques for the new materials and processes. I am happy to record that our scientists and engineers in the field of nondestructive testing have met these challenges by developing appropriate technologies and equipments and capabilities within the country. Many examples can be given. One case is the testing of the large LCA carbon fibre composite wings for which manufacturing technology was established along with inspection technology and equipments. HAL jointly with CAIR and NDT experts designed and developed the C-Scan equipment for the full-scale wing testing and X-ray and ultrasonic testing for honeycomb bonded sandwich structures. Lot of people were skeptical about the development of such NDT equipments in India but we succeeded. Our cost was about 20% of cost for import. Similarly, the large auto-clave with all its online monitoring of temperature pressure and other parameters was developed by NAL and its industry partner. Developments were also taken place in the field of X-Ray radiography of castings, cluster welds. Today, we can monitor the X-ray images on a screen and make immediate decisions unlike in the earlier times where we used to take images on films to be developed and examined after several hours and then analysis to take decision. We also have scanning methods as in health care industry, which gives 3D images and facilitate more quantitative analysis. Our R&D labs and industry partners should make much more efforts for marketing and commercializing these developments worldwide. We also do not upgrade the technologies and equipments continuously and sometimes loose out even in the Indian market. We should make adequate efforts in developing skills among NDT technicians and engineers. Several of the training institutes for training and certification in NDT are ill equipped both in infrastructure and experienced faculty. Who or what has been the biggest inspiration and motivation behind your successes which is continuing even now? During my early professional life, the motivation came mostly from professional bodies and societies like IIM, ISNT (ISNDT that time), Institution of Engineers, Aeronautical Society of India. Senior members of these associations and several R&D institutions who were top leaders and visionaries were my role
December 2017
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models. These associations and the visionary leaders encouraged, motivated, helped us network, do team building and helped keep a positive mind set continuously. Many times, the thought of leaving HAL crossed my mind, it was my friends and colleagues from these societies and my mentors in HAL who advised me against it. When my work was appreciated by colleagues and it also created employment, I felt a sense of pride and this inspired me and my team to do more. Founding of Society of Indian Aerospace Technologies & Industries (SIATI) for enhanced private industry participation particularly small and medium scale industry in aerospace and support from all stakeholders has been very motivating. This year is SIATI’s silver jubilee and we are celebrating it throughout the year all over the country. Many industries are given awards of excellence for their achievements in indigenous development of aerospace materials, processes and equipments. So far, SIATI has honoured 156 industries and 16 individual entrepreneurs. SIATI member industries have become not only cost effective and reliable quality conscious, supply chain partners but also R&D and Innovation partners for India’s space and aircraft and defense projects. Some of them have also emerged as exporters of their products and services and this is very inspiring.
to create suitable eco-system for the growth of start-ups will be helpful. Association may also join with the governments and industries for establishing skill councils and quality training institutions in concerned fields to provide skill training and certification to provide adequate number of qualified human resources.
C.G.Krishnadas
In an article in one of the journals, you were described as an Engineer, Scientist, Manager and Academician. Which one of these do you associate yourself the most? I always believed that a good manager must be a good teacher, and sustain and grow in his field of specialization either as Engineer or Scientist. What one knows, one should be able to teach one’s colleagues and the team will become stronger and do great things together. There must be a good combination of all the above elements to be successful and to help others to be successful. With the new initiatives like “Make in India“, “Skill Development” etc. we are seeing an increase in young engineers wanting to be entrepreneurs and create new startups . What do you see the role of professional bodies in fostering this culture? We all have a big role. First of all this is a very good sign that many youngsters are getting charged with this mission and motivation of “Make in India”. Professional societies should actively continue to encourage them to work together for these national initiatives and help learn from each other. In engineering, inventions and innovations will take place only when we have multi disciplinary teams working together with passion and dedication. All professional bodies should encourage knowledge and skill development by organizing seminars and workshops for these youngsters using the expertise available within the societies and elsewhere. They are our future and we have a duty towards them. The issue of finance will always be there but there are several agencies today, who are coming forward to assist. What professional bodies may do is to create awareness workshops for the young entrepreneurs / start-ups to enable them for wise evaluation and choosing of such financial offers particularly from venture capitalists. Skill development in entrepreneurship will be welcome. Celebrating success by encouraging through awards for achievements and taking up common issues and challenges with appropriate forums in the government for policy changes / policy formulation
September 2017
What would be your dream for the aerospace industry in India ? My dream for aerospace industry in India is maximizing indigenous manufacture of aerospace needs of our country for both military and civil. We should collaborate wherever necessary with international OEMs and make the ‘Make in India’ mission a success and beat the import lobbies. Our biggest problem in India inspite of efforts at the top, is the presence of a strong import lobby with vested interests who decry indigenous development. LCA and ALH are two great examples of indigenous technologies which are far superior to anything a foreign supplier can offer in that category. Our products are onpar or better in most cases, so we should become independent. Like the other countries, China, Russia, USA, France, who encourage their own industries, we should do the same in India. My dream is to work in harmony with the government and the import lobby should not be allowed to flourish. Also, our retired people working as agents for foreign companies should not be encouraged and instead should work for Indian companies and bring in international collaboration. We should encourage indigenization and indigenous products wherever possible. Let thoughts and ideas come from everywhere and let us digest it and collaborate internationally by becoming a global player. SIATI and IIAEM are good examples of these philosophies. We have managed to get a lot of joint ventures, strategic collaborations and influencing the government and other external agencies. Would you like to share something about activities other than your professional ones and your other passions? I like peaceful & soothing activities like music, meditation, gardening, nature walk & tree planting. Photography, reading & writing books is also something that I enjoy. I am also involved with a few charitable institutions to support poor school children and for education and support of physically and mentally challenged children and the like. Let me end by saying that I am delighted to note the growth of ISNT and its activities and the publication of the JNDE, which is of a high standard. I will be happy to associate with ISNT and support its activities to take ISNT to higher national and international levels. I feel it’s time, we hold a World Conference on NDT in India, similar to the one held two decades back to demonstrate the new positive environment prevailing in the country and to showcase the world our capabilities and achievements in the various sectors. We thank Dr. Nair for taking time to share his vast decades of experience for the benefit of the readers of this journal and will act as an inspiration and motivation to do more. As interviewed by Dr.Shyamsunder Mandayam, Chairman, National Certification Board, ISNT
Prediction of Mechanical Properties in Tempered Dual Phase Steel through Non-Destructive Magnetic Hysteresis Loop Technique *J. N. Mohapatra, Arbind Kumar Akela, Satendra Kumar and Prakash Rao S. JSW Steel Limited, Toranagallu, Bellary 583275 Karnataka, India. *E-mail: jitendra.mohapatra@jsw.in ABSTRACT Dual phase steel with different content of martensite were prepared by quenching a C-Mn steel after soaking at various temperatures in the range of 700-850oC. With the increase in martensite content the strength was found to be increased with decrease in ductility. The steels were tempered at 300oC for 1 hour to improve the ductility as the steels are used in the oil and gas industry in tempered condition for better hydrogen embrittlement resistance. Optical and scanning electron microscope conď€ rms the formation of dual phase and tempered martensite microstructure. Magnetic hysteresis loop (MHL) measurements were carried out to evaluate mechanical properties through a nondestructive magnetic device. The measured coercivities were used to predict micro-Vicker’s hardness and compared with the measured values found to be well within the acceptable range. The results inferred that monitoring coercivity of the MHL could estimate the extent of hydrogen embrittlement induced change in mechanical properties. 1.0
INTRODUCTION
D
ual phase steels possess unique feature of low yield strength, high tensile strength, high work hardening rate at early stage of plastic deformation, continuous yielding, good ductility, and formability owing to their use in the automotive sector for obtaining high strength/weight ratio to reduce the fuel consumption and consequently reduction in CO2 emission [1-4]. The properties of DP steels are achieved by its microstructure consisting of optimum combination of martensite and ferrite. The martensite gives the superior strength whereas the ferrite provides the adequate ductility. Generation of martensite phase through water quenching is a prominent method of achieving mechanical properties, however tempering is usually conducted to improve the ductility of the steels [5, 6]. Through tempering the yield strength and tensile strength decreases with the improvement in the elongation of the steels. In oil and gas industry various components in contact with the hydrogenous materials resulted in diffusion of hydrogen to the materials causing hydrogen embrittlement lead to catastrophic failures. Appropriate tempering to the steel resulted in an excellent resistance to hydrogen embrittlement which makes the material a potential candidate for oil and gas industries where hydrogen embrittlement is of the major problem [7]. The hydrogen induced embrittlement resulted in decrease in ductility and increase in strength of the materials with a brittle mode of fracture. Hence by periodic monitoring the change in ductility or strength of the components in use through noninvasive means could helpful for the assessment of the
service conditions of the components. With proper preventive actions could helpful for the prevention of catastrophic failure of the components. As the yield strength and tensile strength is related to hardness of steels, measuring the hardness could also represent the relative change in mechanical properties. Numerous works could be found for the evaluation of microstructure and mechanical properties of the steels [8-11], however a limited number of literatures available for the study of physical properties such as electrical, magnetic, ultrasonic etc. of the steels [12-15]. For the precise control of microstructure and mechanical properties of the steels and their evaluation is a need to develop suitable advanced non-destructive evaluation methodologies [16]. Since magnetic properties of the steels are strongly dependent on the microstructure, magnetic based techniques such as magnetic hysteresis loop and magnetic Barkhausen emissions are in growing demand. Evaluation of change in structures in terms of ageing, creep, fatigue, carburization, decarburization, embrittlement and residual stresses effects etc. through magnetic based techniques are a great interest by the researchers for the high sensitivity of the techniques [17-21]. Although magnetic based techniques are not well established for the evaluation of materials degradation in oil and gas industries more research is required for the establishment of the techniques in such ď€ eld. In our earlier study [22], a very good correlation was established between the volume fraction of martensite, hardness and tensile strength with the coercivity of the steels. In the present investigation, specimens with varying martensite volume fractions were tempered to improve the September 2017
ductility. Coercivity was monitored on the samples whereas hardness was predicted from the regression equations of our earlier study [22]. Hv = 36.38 Hc-120.7 ……………………… (1)
present in the sample due to cold rolling. Microstructure of dual phase steel soaked at 700-850oC with 50oC step for 15 min followed by water quenching is shown in Fig. 2 (a)-(d) and their corresponding tempered microstructres are shown in Fig.2 (e)(h). The corresponding SEM micrographs are shown in Fig. 3.
Where Hc = Coercivity and Hv = Micro Vicker’s Hardness Micro Vicker’s hardness tester was used to measure the hardness of the steels. The measured hardness was compared with the predicted values. The results were found to be well within the acceptable range. As the hardness is related to the yield strength and tensile strength of steels, by monitoring the coercivity the mechanical properties of dual phase steels could be evaluated very precisely in a non-invasive way. 2. EXPERIMENTAL In the present study, C-Mn dual phase steel of thickness 1.3mm in full hard condition is used for further treatment. The chemical composition of the steel sample is given in Table-1. C
Si
Mn
P
S
Al
N
Cr
Mo
Fig.1: (a) Microstructure and (b) SEM micrograph of as-received DP steel.
Ni
0.08 0.02 1.95 0.013 0.002 0.036 0.0039 0.02 0.15 0.01 Ta b l e - 1 : C h e m i c a l c o m p o s i t i o n o f t h e s t e e l
Specimens of dimensions 120 mm×50 mm soaked at different temperatures in the range of 700-850oC with a step of 25oC and a soaking time of 15 minutes (mins) followed by water quenching (WQ). The heat treatment produced martensitic phase in the range of 21-58% [22], were tempered at 300oC for 1hour (hr) followed by air cooling (AC) to improve the ductility of the steels. Mechanical properties were evaluated with same heat treatments on standard tensile specimens. Magnetic hysteresis loop (MHL) measurements were carried out on the specimens from both the sides (top and bottom) at a magnetizing eld of 80 kA/m and magnetizing frequency of 0.05 mHz using a magnetic nondestructive evaluation (NDE) device (MagStar) before subjecting the specimens to further heat treatment. MHL measurements were carried out on the samples to monitor the coercivity. Microstructure variation study was conducted using optical and scanning electron microscopy (SEM) by polishing the sample to mirror nish and etching the samples using Nital. Volume fractions of martensites were measured using image analysis software by area fraction method. Mechanical properties were evaluated in Zwick made tensile testing machine at a strain rate of 0.008/sec. Micro Vicker’s hardness tests were conducted at a load of 0.5kg with minimum ve indentations on each sample. 3. RESULTS AND DISCUSSION 3.1. Microstructure and mechanical properties The optical image and SEM micrograph of as-received (As-R) DP steel is shown in Fig.1 (a) & (b) respectively. The martensitic phases are in elongated form along the rolling direction. A high densityof dislocations and residual stress are expected to be September 2017
Fig. 2: Microstructure of dual phase steel (a)- (d) soaked at temperature between 700-850oC with 50oC step for 15 min followed by water quenching, (e)-(h) are their microstructure after tempering at 300oC for 1hr.
The measured volume fraction of martensite and mechanical properties of the samples is shown in Table-2. The as-received sample contains a volume fraction of martensite 34%. The samples soaked at 700oC/WQ showed a low volume fraction of
martensite 21% and the % of martensite increased with increase in soaking temperature and a maximum of 58% is obtained at the soaking temperature of 850oC [22]. The sample soaked at 700oC/WQ showed low tensile strength and the tensile strength increased with increase in soaking temperature due to the increase in volume fraction of martensite. A decrease in % of elongation was also found with increase in volume fraction of martensite. The Proof Stress (PS) at 0.2% strain was low at 725oC and increased with further increase in soaking temperature.
Fig.3: SEM Micrograph of dual phase (a)- (d) soaked at temperature between 700-850oC with 50oC step for 15 min followed by water quenching, (e)-(h) are their SEM micrograph after tempering at 300oC for 1hr.
The Ac1 and Ac3 temperatures for the said composition are 704 and 858oC, as calculated using the Andrew’s relation given below [23]. Ac1 = 723 - 16.9Ni + 29.1Si-10.7Mn + 16.9Cr + 290As …………..(2) Ac3 = 910 - 203√(C) + 44.7Si-15.2Ni + 31.5Mo + 104V ………….(3) Where: Mn, Ni, Cr, Mo – mass contents of the elements in the investigated steel, Cγ – carbon concentration in the austenite. As 700oC is below the Ac1 temperature there is no possibility of increase in volume fraction of martensite and at 725oC & 750oC temperatures there is a possibility of increase in small volume fraction of martensite however tempering and dissolution of existing martensites resulted in a total low volume fraction of martensite compared to the as-received sample. The increase in volume fraction of martensite with the increase in soaking temperature are due to the transformation of ferrite fractions of steel in to austenite phase in the inter critical temperature range which further transformed to martensite during water quenching. The martensite transformation being diffusion less resulted in increase in hardness of the steel due to the lattice distortion. It is attributed that the increased volume of material during austenite to martensite transformation induces high density of dislocations at the ferrite-martensite grain boundary [24, 25]. Rashid et. al., has reported 2-4% increase in volume during the martensitic transformation process [26]. After tempering the tempered martnsitic microstructure can be seen such structure with presence of dislocations in the ferrites due to volume change from austenite to martensite is reported earlier [6]. The change in micro-Vicker’s hardness of the steels in asquenched condition and after tempering is shown in Fig.4. The hardness is increased with increase in soaking temperature due to the increase in volume fraction of martensite phase. The martensite phase obstructs the dislocation movement to increase the hardness of materials at small volume fractions and at higher volume fractions the hardness is more due to the hard martensite phase itself. After tempering the hardness is expected to decrease with decrease in tensile strength and
Sample As-R 7000C 7250C 7500C 7750C 8000C 8250C 8500C ID
Martens 34 ite
21
26
33
40
43
52
58
YS 622 PS(MPa)
414
322
365
415
403
522
680
UTS 905 (MPa)
523
597
677
869
801
857
1181
4.3
31.2
34
24.6
17.7
18.5
16.9
8.6
% EL
Table-2: Volume fraction of martensites (%), YS, UTS and % EL.
Fig.4: Micro Vicker’s hardness of the DP steels soaked at different temperatures in as-quenched condition and tempered at 300oC/1h/air cooled.
September 2017
increase in ductility (% of elongation). Such hardness decrease is found to be more on tempered samples having higher volume fraction of martensites. The lattice distortions caused by transformation of martensites would be more for higher volume fractions of martensites and hence by tempering the lattice distortions gets minimized more due to highly unstable microstructures tens to stabilize. 3.2. Magnetic properties The magnetic hysteresis loop of the samples at selected soaking temperatures before and after tempereing is shown in Fig. 5.
The magnetic domains are restricted by several metallurgical factors such as grain boundary, precipitates, dislocations and secondary phases present in ferromagnetic materials resulting in a high value of coercivity. In addition presence of compressive residual stress resulted in increase in coercivity of the materials. With the decrease of any of the above factors resulted in decrease in coercivity. In the present case with the increase in volume fraction of martensite as the seconday phase resulted in increase in coercivity of the steels. With the tempering treatment the compressive residual stress generated through water quenching gets relaxed resulted in decrease in coercivity of the steels. The mechanical properties of materials and hardness gets inuenced by grain boundary, precipitates, dislocation density, secondary phase and the type of stress present in materials. As the coercivity and mechanical properties are inuenced by the metallurgical parameters in a similar trend, both the coercivity and hardness were found to be changed in a similar trend that is increased with volume fraction of martensite phases and decreased through tempering. Hence by monitoring coercivity could provide the information about change in metallurgical parameters or mechanical properties. The hardness was predicted by using coercivity in the equation(1) and also measured using micro Vicker’s hardness tester. A plot of predicted and measured hardness for different soaking temperatures is shown in Fig.7. Fig.7: Predicted and measured hardness of tempered DP steels after soaking at d i f f e r e n t temperatures.
Fig.5: Magnetic hysteresis loop of samples in as quenched conditions soaked at (a) 700oC, (b) 750oC, (c) 800oC and (d) 850oC with their corresponding tempered conditions, (a′)-(d′) are their corresponding high magnication loops at the coercive regions.
The change in coercivity before and after tempering is shown in Fig.6. The coercivity decreased with tempering indicating magnetic softness of the samples. The degree of softness increased through tempering on the samples with higher volume fraction of martensite phase. Coercivity is related to the pinning force of magnetic domain wall and dened the maximum pinning force against domain wall movement in ferromagnetic materials [27]. Fig.6: Change in coercivity of the DP steels soaked at d i f f e r e n t temperatures in asquenched condition and tempered at 300oC/1h/AC.
September 2017
It is observed from the gure that the measured hardness values and hardness values calculated based on magnetic coercivity are in very good agreement. Hence it is possible to predict the mechanical properties of DP steel by measuring the coercivity through magnetic hysteresis loop measurement. 3. CONCLUSIONS Magnetic hysteresis loop measurements were carried out to monitor the coercivity on tempered DP steels with varying martensite contents. The micro Vicker’s hardness was predicted from coercivity values. The hardness was also measured through micro Vicker’s hardness tester and compared to the predicted values revealing very good accuracy. As hydrogen embrittlement of DP steel in oil and gas industries is resulting in decrease in ductility with increase in strength, the results clearly show that magnetic hysteresis loop would be a very potential tool for the non-destructive evaluation of change in strength in dual phase steels for the evaluation of hydrogen induced embrittlement. A detailed study is required for the laboratory scale hydrogen embrittlement and its evaluation through magnetic hysteresis loop technique for the application of the technique in the oil and gas industries.
5.0
REFERENCES:
1. M. Sarwar, R. Priestner, Inuence of ferrite-martensite microstructural morphology on tensile properties of dual-phase steel, J. Mater. Sci., 1996, 31, p. 2091–2095. 2. A. Bayram, A. Uguz, M. Ula, Effects of microstructure and notches on the mechanical properties of dual-phase steels, Mater. Charact 1999, 43, p.259–269. 3. M.H. Saleh, R. Priestner, Retained austenite in dual-phase silicon steels and its effect on mechanical properties, J. Mater. Process. Technol 2001,113, p.587–593. 4. Satendra Kumar. Mrigandra Singhai. Rahul Desai. Srimanta Sam. Pradip Kumar Patra, Development of Advanced High Strength Steel for Improved Vehicle Safety, Fuel Efciency and CO2 Emission, J. Inst. Eng. India Ser. D; DOI 10.1007/s40033-015-0100-x. 5. T. Sirinakorn, V. Uthaisangsuk, and S. Srimanosaowapak, Effects of the Tempering Temperature on Mechanical Properties of Dual Phase Steels, J Metall Mater Miner, 2014, 24(1), p 13–20. 6. A. Anazadeh Sayed, Sh. Kheirandish, Effect of the tempering temperature on the microstructure and mechanical properties of dual phase steels, Materials Science and Engineering A, 2012, 532, p.21-25. 7. Faisal I. Iskanderani, Development of tempered dual phase steel for hydrogen service in the oil and gas industries, Oxford Research Forum Journal, 2008, 3 (1), p. 3-12.. 8. J. Adamczyk , A. Grajcar, Heat treatment and mechanical properties of low-carbon steel with dual-phase microstructure, Journal of Achievements in Materials and Manufacturing Engineering, 2007, 22(1), p.13-20. 9. M. Pouranvari, Tensile strength and ductility of ferritemartensite dual phase steels. Assoc Metall Eng Serbia, 2010, AMES, Scientic paper,UDC: 669.141.3, MJoM, 16(3), p 187– 194V. 10. Colla, M. De Sanctis, A. Dimatteo, G. Lovicu, A. Solina, and R. Valentini, Strain Hardening Behavior of Dual-Phase Steels, Metallurgical and Materials Transactions A , DOI: 10.1007/s11661-009-9975-1. 11. S. Sodjit and V. Uthaisangsuk, A Micromechanical Flow Curve Model for Dual Phase Steels, J Metals Mater Miner, 2012, 22(1), p 87–97. 12. L. Gao, Y. M. Zhou, J. L. Liu, X. D. Shen, Z. M, Ren, Effect of water quenching process on the microstructure and magnetic property of cold rolled dual phase steel, Journal of Magnetism and Magnetic Materials, 2010, 322, p. 929-933. 13. S. Ghanei, M. Kashe, and M. Mazinani, Eddy Current Nondestructive Evaluation of Dual Phase Steel, Mater Des, 2013, 50, p 491–496. 14. S. Ghanei, A. Saheb Alam, M. Kashe, and M. Mazinani, Nondestructive Characterization of Microstructure and Mechanical Properties of Intercritically Annealed Dual-Phase Steel by Magnetic Barkhausen Noise Technique, Mater Sci Eng A, 2014, 607, p 253–260.
15. S. K. Akay, M. Yazici, A. Avinc , The effect of heat treatments on physical properties of a low carbon steel, 2009, 10(1), p.1-5. 16. M. Pouranvari, Tensile strength and ductility of ferritemartensite dual phase steels. Assoc Metall Eng Serbia, 2010, AMES, Scientic paper, UDC: 669.141.3, MJoM, 16(3), p 187– 194. 17. J.N.Mohapatra, A .K.Panda, M.K.Gunjan, N.R.Bandyopadhyay A.Mitra and R.N.Ghosh, “Ageing Behavior Study of 5Cr-0.5Mo Steel by Magnetic Barkhausen Emission and Magnetic Hysteresis Loop technique”, NDT & E Int., 2007, 40, p. 173-178. 18. A.Mitra, J.N.Mohapatra, J.Swaminathan, M.Ghosh, A.K.Panda and R.N.Ghosh, “Magnetic evaluation of creep in modied 9Cr–1Mo steel” Scripta Mat.,2007, 57, p.813-816. 19. Chen Xing, Li Luming, Hu Bin, Cui Xiaojie, Deng Yuanhui, Yang Dezhi and Yang En, Magnetic evaluation of fatigue damage in train axles without articial excitation, Insight, 2006, 48(6) p. 342-345. 20. Gerd Dobmann, Iris Altpeter, Klaus Szielasko, Markus Kopp, Nondestructive damage characterization with examples of thermal aging, neutron degradation and fatigue, Journal of Theoritical and Applied Mechanica, 2006, 44(3), p. 649-666. 21. Nishanth S. Prabhu, J. Joseyphus, T.S.N.Sankatnarayan, B. Ravikumar, Amitava Mitra and A.K.Panda, Residual Stress Analysis in Surface Mechanical Attrition Treated (SMAT) Iron and Steel Component Materials by Magnetic Barkhausen Emission Technique, IEEE Transactions on Magnetics, 2012, 48(12) p.4713-4717. 22. J. N. Mohapatra, Satendra Kumar, Arbind Kumar Akela, Prakash Rao S, and Marutiram Kaza, Magnetic hysteresis loop as a tool for the evaluation of microstructure and mechanical properties of DP steels, Journal of Materials Engineering and Performance, 2016, 25(6) p. 2318-2325. 23. K.W. Andrews, Empirical formulae for the calculation of some transformation temperatures, Journal of the Iron and Steel Institute 203 part: 7 (1965) 721-727. 24. R G Davies, Inuence of Martensite Composition and Content on the Properties of Dual- Phase Steels. Metallurgical Transactions A 1978, 9(5), p. 671-679. 25. Fatih Hayat, Huseyin Uzun, Effect of Heat Treatment on Microstructure Mechanical Properties and Fracture Behaviour of Ship and Dual Phase Steels; Journal of Iron and Steel Research, International. 2011, 18(8), p. 65-72. 26. MS Rashid. Relationship Between Steel Microstructure and Formability, In: Davenport AT, editor. Formable HSLA and dual phase steels. New York: Metallurgical Society of AIME; 1979. p. 1–24. 27. D.C. Jiles, Introduction to Magnetism and Magnetic Materials, 2nd ed., Chapman and Hall, New York, 1991, p 179–191.
September 2017
Pulsed Eddy Currents: Improvements in Overcoming Adverse Effects of Galvanized Steel Weather Jacket V. Demers-Carpentier, M. Rochette, F. Hardy, M. Grenier, C. Tremblay, M. M. Sisto and A.Potvin† Eddy, 2800, rue Louis-Lumière, Québec, Canada. †E-mail: apotvin@eddy.com@company.com ABSTRACT Pulsed Eddy Current (PEC) has been successfully deployed over the last decades for a variety of corrosion-related applications, most notably for Corrosion Under Insulation (CUI) inspections, Corrosion Under Fireproong (CUF) and Flow Accelerated Corrosion (FAC). This technology has proven to be an efcient screening tool, allowing for detection of corrosion without having to remove coating or insulating material over typical pipes, tanks and vessels. However, the use of this technique has been severely limited for components wrapped in galvanized steel weather jacket, which abound in some geographic markets. This paper discusses the challenges of working with galvanized steel as well as some of the solutions that allow quality PEC inspection of such components. We present the most recent improvements in PEC technology, including a novel PEC probe specically designed for inspections through ferromagnetic weather jackets. This new probe design, combined with an optimized analysis algorithm, greatly enhances signal quality and defect sizing accuracy when measuring through ferromagnetic jacket materials. Laboratory and eld results will be presented and analyzed. 1.0
INTRODUCTION
P
ulsed Eddy Currents (PEC) is a versatile non-destructive evaluation technique that can measure wall thickness of conductive components at high lift-offs [1]–[3]. PEC is well suited for non-destructive analysis of Corrosion Under Insulation (CUI), Corrosion Under Fireproong (CUF) and Flow Accelerated Corrosion (FAC) in carbon steel structures like pipes, tubes [4], [5], vessels, sphere legs, etc. PEC is best used as a screening tool owing to its ability to inspect in-service components through insulation and cladding. As no insulation stripping is required, PEC allows the asset owners to expand the scope and frequency of screening inspections without increasing the facilities downtime. This broader screening allows to identify potential corrosion areas outside the shutdown period, and enables a more focused application of complimentary methods such as radiography and ultrasounds during shutdowns. The PEC technology is routinely used to inspect through thermal insulation up to 300mm thick and can tolerate up to about 1mm thickness of aluminum or stainless-steel weather jackets covering the insulation. However, conventional PEC systems detection and sizing performance is impaired by galvanized steel (GS) jackets due to the ferromagnetic properties of this material. In this paper, we discuss how GS affects PEC signals and we present a novel (patent pending) PEC probe design that mitigates these effects. September 2017
1.1 Principle of operation of Pulsed Eddy Currents The principle of operation of PEC is described as following. A magnetic pulse is generated by a coil placed at some elevation (or lift-off) from the surface of a component under inspection, which must be ferromagnetic and conductive. During a rst excitation phase, the pulse remains active long enough for the magnetic eld to penetrate the full thickness of the component. Following the abrupt extinction of the pulse, eddy currents are generated in the metal mass to oppose the rapid change in magnetic eld. These currents induce a secondary magnetic eld which can be sensed by a magnetic sensor and decays over time. In this phase, referred to as the reception phase, the sensor generates a voltage signal that is recorded and analyzed. The voltage signal as function of time is referred to as an A-scan. The shape and decay rate of the A-scan are directly related to the thickness of the component being inspected. By controlling the length and the intensity of the magnetic pulse, the PEC technique can be used to inspect carbon steel plates with thickness ranging from a 3 mm to 100 mm. 2 0 IMPACTS OF GALVANIZED STEEL WEATHER JACKETS ON PEC SIGNALS Galvanized steel interacts with PEC pulses in many ways [6]. First, as the material is ferromagnetic, it screens part of the magnetic eld generated by PEC during the excitation phase. Hence, only a fraction of the magnetic eld emitted by a PEC probe reaches the surface under test. Correspondingly, during
the reception phase the intensity of the secondary magnetic eld from the plate that reaches the magnetic sensor is also reduced.
Figure 1: Normalized magnitude of the magnetic ux in a carbon steel plate covered with 50 mm (2 in) insulation (non-conductive, non-magnetic) and (A) 0 mm, (B) 0.5 mm (0.020 in), and (C) 1 mm (0.039 in) of galvanized steel.
To evaluate the importance of this effect, we calculated the magnitude of the magnetic ux density (B) in a 12.7 mm (0.5 in) thick carbon steel plate, 50 mm (2 in) liftoff and up to 1 mm (0.039 in) GS jacket. The results, computed in COMSOL® Multiphysics®, appear in Figure 1. With only 0.5 mm (0.02 in) of GS, the maximum magnitude of the magnetic ux in the plate drops under 40 % of the value without a jacket. A second detrimental effect of GS on PEC signals is that it enlarges the magnetic footprint of PEC probes. The magnetic footprint is dened by the spatial distribution of the intensity of the B eld (Magnetic ux density). More precisely, we dene the area of the magnetic footprint as the region (on the inspected plate) encompassed by the isoline at 50% of the maximum intensity of B. PEC offers the best sizing accuracy over defects larger than the probe’s footprint. Over defects smaller than the footprint, PEC signals are inuenced by the defect and the surrounding nominal plate thickness. In this situation, the thinnest region (the defect) is averaged out by the thicker surrounding wall, leading to underestimating the defect’s wall loss. This is called defect undersizing. GS amplies defect undersizing by enlarging the probe’s footprint. This happens because the jacket captures and spreads out the magnetic eld from the probe (in the excitation phase) and from the inspected plate (in the reception phase). Another detrimental effect of GS jackets is revealed during the PEC reception phase. As GS is conductive, eddy currents in the jacket generate a magnetic eld recorded by the probe’s sensor. The rst few milliseconds of the received A-scan are therefore typically dominated by the GS signal. Fortunately, the decay of the GS contribution is relatively sharp compared to the signal from the much thicker surface under test. Figure 2 shows a typical A-scan from a 12.7 mm (0.5 in) thick Figure 2 Typical Ascans measured with and without GS jacket. The gain is a d j u s t e d t o superimpose A-scans beyond 20 ms
component, at 50 mm (2 in) liftoff, with and without a GS jacket. The GS contribution may partially mask the signature of some types of defect, especially defects smaller than the probe’s footprint. Finally, GS jackets vibrate during the PEC excitation and reception phases. Each time a PEC probe res a pulse, the GS jacket is attracted to the probe’s magnetic eld, causing a transient mechanical vibration. At a pulsation rate of 1–100 Hz, vibrations disrupt PEC signals. Typically, the shape of vibrations and the spectral content vary according to several uncontrolled factors: the GS jacket thickness, the mechanical dampening from the insulation, the quality and tightness of jacket xations, etc. In addition, vibrations are synchronized to PEC pulses and cannot be eliminated by averaging over multiple pulses. All the effects outlined above offer a sense of challenges facing PEC on components wrapped in galvanized steel, which usually result in reduced detection and sizing capabilities of conventional PEC systems. However, mitigation measures are possible. 3.0 A NOVEL PROBE DESIGN FOR INSPECTION THROUGH GALVANIZED STEEL WEATHER JACKET Improvement of analysis agorithms and GS jacket vibration damping are among the techniques that can mitigate the adverse effects of GS jackets [6]. However, in search for a more fundamental solution, we developed a PEC probe specially designed for inspection through GS weather jacket. The novel feature of this patent pending design is that permanent magnets are positioned close to the probe’s magnetic sensor. These magnets are employed to magnetically saturate the GS under the probe. The magnetic permeability of the jacket is therefore signicantly reduced over a region covering the magnetic footprint of the probe on the jacket. The multiple advantages of this concept are presented in the following sections. 3.1 Improved A-scan signal-to-noise ratio The screening effect described in Section 2 is greately reduced, owing to the lower magnetic permeability of the saturated GS jacket. Hence, during the excitation phase a lower portion of the magnetic pulse emitted by the PEC probe is captured by the jacket. Similarly, during the reception phase, a larger portion of the PEC secondary magnetic signal from the inspected component can reach the magnetic sensor. In addition, the permanent magnets act as a sort of anchor, magnetically attracting the jacket to the probe and effectively preventing mechanical vibrations. All these effects contribute to improve the A-scans signal-to-noise ratio compared to a conventional probe design. 3.2 Attenuated contribution of the GS jacket on the A-scan During the detection phase, the saturated GS jacket still generates eddy currents. However, the contribution of the GS jacket on the A-scan is reduced compared to the unsaturated case, although not completely eliminated. Figure 3 illustrates an example of A-scan captured on a 0.5 inch plate with 2 inch September 2017
insulation and 1mm GS jacket. The red dashed curve is captured with a conventional probe, while the black curve is captured with the GS probe. The contribution from the GS jacket is attenuated and effectively shortening the portion of the Ascan where it dominates over the component signal. Indeed, the GS signal is still well visible in the rst 5ms of the A-scan, compared to a signal captured without jacket (thin line), but the difference is sufcient to improve the sizing of small defects whose signature may otherwise be partially masked by the GS contribution.
diameter ranging from 2 to 6 inches and wall loss ranging from 33% to 66% of the nominal. Table 1 shows aggregated statistics over all the tested defects for the sizing error, dened as the difference in measured wall thickness between data points captured with and without GS jacket for the same plate, defect and insulation thickness.
Table 1: Sizing error compared to sizing obtained without GS jacket.
3.3 Reduction of the probe footprint The probe’s footprint shrinks to dimensions approaching those found without jacket, which also diminishes the undersizing of small defects. To illustrate this phenomenon, Figure 4 (left) shows simulations of the footprint for a conventional probe with and without GS jacket (0.5mm thick) as well as the footprint for the GS-specialized probe design, assuming a 12.7 mm (0.5 in) plate and 50 mm (2 in) of insulation. In this example, on GS jacket the specialized probe footprint area is 66% of the footprint found for the conventional probe and it is approximately equal to the footprint found without jacket. Figure 4 (right) shows how the footprint dimension along the AB axis varies with the lift-off (LO or insulation thickness): on both 0.5mm and 1mm of GS jacket, the GS-specialized design can bring the footprint back to the no-jacket case. The reduction in footprint is related to the level of saturation of the jacket: for a thick jacket, the saturation of the simulated design is not complete and the footprint is slightly larger than the one found with thin jacket.
With the GS-specialized probe, the average sizing error induced by the presence of the GS jacket is no more than 5.1%, while the error is as large as 12.3% with a conventional probe. This improved sizing performance was conrmed by tests on real samples. For example, Figure 5 shows 2D sizing maps of a pipe with 203.2 mm (8 inch) outer diameter, schedule 40, 50.8 mm (2 inch) thick insulation, 0.7 mm (0.03 inch) thick galvanized steel jacket, and a ange. Figure 5A shows a map from a conventional PEC probe, affected by enlarged footprint and noise from the galvanized steel vibration, which all contribute to make some defects hard to detect. Figure 5B shows the same sample scanned with the GS-specialized PEC probe. Defects are better detected and sized thanks to the smaller footprint of the probe and the improved A-scans signal-to-noise ratio. The probe is even able to detect a defect near the ange, which was otherwise undetected with a conventional probe.
Figure 5 : 2D sizing maps of (A) conventional PEC probe (B) galvanized steel-specialized probe
Figure 4: (Left) Comparison of footprint simulated on 0.5 inch plate with 2 inch insulation. (Right) Evolution of footprint with insulation thickness (lift-off, LO) for conventional and GSspecialized probes on 0.5 inch plate.
4.0
EXPERIMENTAL RESULTS
The GS-specialized probe was tested in laboratory environment on a set of 30 reference defects machined on carbon steel plates with thickness ranging from 0.25 inch to 1 inch. Insulation thickness values comprised between 0.5 inch and 2 inch and GS jacket thickness of 0.5 mm and 1 mm were considered. The defects were machined with at bottom cylindrical shape, September 2017
One minor disadvantage of the proposed design is that the probe sticks onto the jacket due to the attraction of the magnets. Hence, the probe is more difcult to move than a conventional design, particularly on thick jackets. Still, this may turn into an advantage in some situations, like long inspections on vertical pipes or vessels, as the probe stays in place with no need for the inspector to support its weight. 5.0
CONCLUSIONS
The inspection of components covered with ferromagnetic jackets like galvanized steel is a challenge for conventional PEC systems, as the galvanized steel adversely inuences the PEC
signal in several ways. As a consequence, the defect detection
[2] R. A. Smith and G. R. Hugo, “Transient Eddy-current NDE for
and sizing capabilities of conventional PEC systems are
Aging Aircraft – Capabilities and Limitations,” Insight: Non-
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Destructive Testing and Condition Monitoring, vol. 43, no. 1,
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pp. 14–25, 2001.
novel, patent-pending probe design is based on magnets
[3] V. Demers-Carpentier et al., “Pulsed Eddy Current as an
placed near the PEC magnetic sensors. The magnets saturate
Inspection Tool for Nuclear Power Plants,” in NDT in Canada
the GS jacket, reducing its effective magnetic permeability. The
2016 & 6th International CANDU In-Service Inspection
sizing of defects covered by insulation and GS jacket is
Workshop, Burlington, ON, 2016.
signicantly improved compared to conventional probe
[4] W. Cheng, “Pulsed eddy current testing of carbon steel
designs.
pipes’ wall-thinning through insulation and cladding,” Journal of Nondestructive evaluation, vol. 31, no. 3, pp. 215–224,
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2012. [5] M. S. Sazadeh and M. Hasanian, “Gas pipeline corrosion
[1] J. C. Moulder, M. W. Kubovich, E. Uzal, and J. H. Rose,
mapping using pulsed eddy current technique,” International
“Pulsed Eddy-Current Measurements of Corrosion-Induced
Journal of Advanced Design and Manufacturing Technology,
Metal Loss: Theory and Experiment,” in Review of Progress in
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Quantitative Nondestructive Evaluation, Springer, Boston, MA,
[6] C. Dalpé et al., “Pulsed Eddy Currents: Overcoming Adverse
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Effects of Galvanized Steel Weather Jacket,” presented at the Cofrend 2017, Strasbourg, 2017.
Robotic Inline Inspection and Leak Detection System for Oil and Gas Pipelines Ramineni Ajayraj*, Avinash Kumar, Dr. Krishnan Balasubramaniam, Dr. Prabhu Rajagopal *Email: ajayraj.ramineni@gmail.com ABSTRACT Accurate leak detection and location methods are vital for safe operation of pipeline assets. This paper discusses the development of a spherical robot congured with acoustic sensors, camera, illuminating system and encoders for pipeline inspection. The sensors on the robot monitor the pipeline to detect leaks, corrosion and sediments. A method based on acoustics is proposed for leak detection in gas pipelines. An experimental setup was developed to simulate real life conditions in the pipeline. The robot collects acoustic signals inside the pipeline as it moves along the pipe. The camera is used for visual inspection to detect corrosion and sediments along the pipeline. The visual data together with encoder data is used for localization of the robot to nd the location of the defects. The data recorded was analyzed and leak detection was demonstrated successfully. 1.0
INTRODUCTION
L
eak detection and location methods play a vital role in the integrity management of the pipelines. Even small leakage can grow and cause signicant damage to the environment apart from injuries and fatalities. Various methods are currently used for monitoring pipelines for leak detection. Hydrocarbon sensors [1], ber optics [2], Pipeline Inspection Gauges [3] are some of the widely used approaches. This paper presents the development of a spherical passively propelled robot for leak detection and location in pipelines by using acoustic sensing and visual inspection. To test the working of the robot an experimental setup was built to simulate the real life conditions. Properties of the acoustic emissions were analyzed for various leakage sizes and pressures inside the pipe. This paper is organized as follows: Firstly the need for pipe leak detection and provides a brief introduction to the current technologies available for inspection of the pipelines. Next, the design of the spherical robot for pipeline inspection is described followed by development of experimental setup. Then a brief introduction to the acoustic emission technique and visual inspection is given. The method of experimentation is then explained after which the results are presented and discussed. The paper concludes with directions for further work. 2.0 DESIGN OF THE ROBOT Most of the pipelines used for transporting oil and gas are buried under the ground to avoid trespassing. Also the lengths of these pipelines are in hundreds of kilometers. The robot has to travel hundreds of kilometers inspecting the pipe for leaks and other defects. The major constraint for this operation is the electric charge of the batteries. The batteries could be only used for powering the sensors and not for propulsion of the robot. In view of this, a spherical shape was considered for the robot, as this allows for passive propulsion. Figure 1 shows a September 2017
photograph of the spherical robot prototype developed by the authors. Once the robot is placed inside a pipeline under operation, it will be rolled along the pipeline due to the drag force generated on it by the ow of the pipeline product.
Figure 1. Photograph of the spherical robot
The robot consists of a spherical casing while the payload consists of acoustic, visual, power and odometric systems. The casing protects the payload from harsh conditions inside the pipe. Since the robot has acoustic and visual sensors, it is necessary for the robot to have a controlled motion. To make accurate recordings the camera and acoustic sensors must translate inside the pipe uniformly even when the spherical shell is rolling. So, the robot is designed in such a way that the spherical shell rolls inside the pipe while all the sensors inside the spherical shell translate forward. It is ensured that the rolling motion of the spherical shell does not transfer to the payload. This makes sure that the sensors does not roll along with the spherical shell. This patent pending design of the robot consists of a self stabilizing mechanism that induces controlled, smooth and stable motion of the sensors mounted inside the robot along the pipeline. 3.0 EXPERIMENTAL SETUP An experimental setup was built to simulate real life conditions in gas pipelines. The experimental setup was designed towithstand a pressure of up to 10 bar. The setup consists of pipelines connected at the ends through anges.
To prevent the air leakage at the anges, rubber gaskets are used. Different sizes of leaks were simulated along the pipeline. Two threaded couplers were welded on the pipeline as shown in the gure 2. Bolts with through holes can be fastened into them to simulate the leaks of different apertures. The experimental setup is shown in the gure 2.
Figure 2. Photograph of the experimental setup
There are two parameters that are varied manually while performing the experiments, namely pressure in the pipe and size of the holes on the pipe wall. During the experiments, acoustic signals are recorded using a combination of these parameters and compared. The pressure inside the pipe can be adjusted by a regulating valve which is connected at the outlet hose of the compressor. A provision was made on the pipe to change the size of the leak. Two holes each of 20 mm diameter are drilled on the center pipe with 1 m distance between them. Two M20 nuts are welded at these holes. Holes of different sizes are drilled on ve different bolts as shown in gure 3. The size of the leak on the pipeline can be varied by inserting different bolts in the welded nuts. The leak sizes are varied from 3 mm to 9 mm.
is problem of attenuation of signals in case of using xed AE sensors. As the distance from the source increases, the sensor nds it more difcult to pick up the signal due to wave attenuation. AE can be related to an irreversible release of energy. It can also be generated from sources not involving material failure including friction, cavitation and impact. When a leak occurs, the escaping gas generates turbulence, friction and impact which results in acoustic emission as it passes through the leak hole of a pipeline[4]. AE is different from other non-destructive testing (NDT) techniques in two regards. Firstly the energy is not supplied to the object under examination, instead AE technique listens the energy released by the object. AE tests can be performed on structures while in operation, as this provides adequate loading for propagating defects and triggering acoustic emissions. Secondly the AE technique deals with dynamic processes. The ability to differentiate between developing and stagnant defects is a signicant attraction for using the AE approach. However, it is possible that aws go undetected if the loading is not high enough to cause an acoustic event. AE systems can use multiple sensors during testing in order to record a hit from a single AE event. These AE systems can be used to determine the location of an event source. As hits are recorded by each sensor, the source can be located by knowing the velocity of the wave in the material and the difference in hit arrival times among the sensors. In the present project the arrival time technique is avoided since we are not using xed sensors but using moving sensor. The sensor moves past the defects recording the level of sound and acoustic emission. AE is widely used for detection of leakages in many cases as mentioned below. The properties of the acoustic signals emitted by a leakage on a pressurized pipeline depend on the dimensions, shape of the hole and pressure difference across the leak[5]. This study includes the characterization of the frequency spectrum of the leak signal as the function of crack parameters such as geometry and dimensions, as well as the uid properties such as pressure, density, viscosity etc.
Figure 5. Picture of conguration of circular hole Figure3. a) Female coupler welded for connecting air compressor, b) Nut welded on the pipe wall, a provision for varying hole sizes, c) and d) Bolts drilled with holes of different sizes
4.0
According to this theory, the frequency of the acoustic waves is given as follows [5]: (1)
ACOUSTIC EMISSION TECHNIQUE
Acoustic Emission (AE) refers to the generation of transient elastic waves produced by a sudden redistribution of stress in a material. When a structure is subjected to change in pressure, load, or temperature localized sources trigger the release of energy, in the form of stress waves. These waves which propagate to the surface can be recorded by sensors. But there
where ΔP is the pressure difference in pascals across the pipe wall and D is the diameter of the circular hole and is in mm. It is proven experimentally that the frequency content of the signal due to air leakage depends on the size, shape and morphology of the leak [6]. The analysis of leak signals in this application also shows that the maximum signal change rate of the transient leak signal is related to not only the gas leakage rate, September 2017
but also the leak positions. It increases with the leakage rate increasing or the leak distance decreasing. It is reported that dynamic pressure sensors are used in AE leak detection for gas pipelines [7], they need to be inserted into gas pipelines for picking up leak noise. It is also showed that detecting and positioning of defects in pressure pipe during normal operation of the pipeline is possible by using AE sensors with attached on the outside of the pipeline [8].
At constant pressure the frequency of the acoustic emission having maximum amplitude depends on the diameter of the hole. The frequency decreases with increase in the hole diameter. This is proved experimentally. The experiments were conducted for 3mm, 5 mm and 7 mm holes at 2 bar and 1.2 bar.
5.0 VISUAL INSPECTION Due to the recent developments in digital image processing and computer vision, automated visual inspection is being extensively applied in many elds such as automatic inspection [9], detection of welding defects [10], part measurements [11], assessment of surface texture [12]. This spherical robot described here, introduces a novel vision system with self stabilizing mechanism for the detection and assessment of internal defects of pipeline such as corrosion, sediments, cracks etc. 6.0 METHODOLOGY OF EXPERIMENTS First, the robot is switched on and placed inside the pipeline at one of its end. Then the pipeline end is closed with a circular plate. To simulate a 3mm leak a bolt with 3mm hole is inserted into the nut on the experimental setup and this hole is closed temporarily till the pipeline is pressurized. The pipeline is then lled with pressurized air using a compressor. To simulate a 3mm leak a bolt with 3mm hole is inserted into the nut on the experimental setup and the this hole is closed temporarily till the pipeline is pressurized. The pipeline is then lled with pressurized air using a compressor. The ow of compressed air into the pipeline is stopped after the pressure inside the pipe reaches desired level. Then the leak is opened and the pressurized air is allowed to escape from it. The air escapes with high velocity creating turbulence near the leakage. This in turn generates noise at the leak. Once the desired pressure is obtained, the robot starts recording acoustic signals and video inside the pipe. While it is recording, the experimental setup is lifted up manually on one side. The gravity pulls the robot to other side of the pipe and the robot starts to roll As the robot rolls, it crosses the leak and comes to rest at the other side. The recorded signals are then extracted and analyzed to detect the leaks. There are two parameters that are modied in all the experiments performed: (a) pressure inside the pipe and (b) sizes of the simulated holes. Experiments are carried out with different combination of pressures and sizes of the holes. 7.0 RESULTS AND DISCUSSIONS: A graph of the amplitude of the recorded audio signal against time is plotted for each experiment. Figures 6 and 7 shows the increase in the amplitude of the acoustic signals near the location of the leaks. This can be compared with the output signal when there is no leak as shown in gure 5(a). It can be observed from gures 5(b) and 5(c) that there is an increase in the amplitude of the output signal when the robot approaches the leakage. The spike in the amplitude of the output signal corresponds to the acoustic emission generated by the high velocity uid escaping from the leak aperture. September 2017
(a)
(b)
( c)
Figure 5. Results of acoustic signals recorded by spherical robot with: (a) no leak, (b) 7mm leak and (c) 9 mm leak
Table 1. Dependence of frequency spectrum on pressure and leak size
Results are also shown extracted in table 1. according to which the frequency output is dependent on the leak size and pressure inside the pipe. Higher the pressure, higher the output frequency and higher the leak size, lower the frequency output. The size of the leak could be estimated by using the data about the frequency of the AE having maximum amplitude. The device has to be calibrated to accurately estimate the leak size solely based on the output signal. The camera onboard the robot records live video inside the pipe. The recorded videos are analysed to detect internal defects. Machine learning algorithms are being developed to process the video and nd the defects autonomously. Figure 8 shows a surface anomaly which was captured by the camera on board.
Figure 8. A photograph taken by the robot showing a defect inside the pipe
7.0 CONCLUSION A passive self-propelled spherical robot has been designed and developed for leak detection and location. The experimental results showed that the acoustic method implemented in
spherical robot allows for detecting and characterizing the
Journal of Fluid Mechanics, 213, 234-245.
leaks in pipelines. Internal defects such as corrosion, scaling
[6] Andreas J. Brunner and Michel Barbezat. (2006). “Acoustic
and blockages were detected by using visual sensors
emission leak testing of pipes for pressurized gas using active
incorporated in the spherical robot. The spherical robot
ber composite elements as sensors”, Journal of Acoustic
proposed here could offer a practical solution for the inspection
emission, vol 25, pp.42-50, 2007
of existing pipeline networks. Thorough experiments are being
[7] L. Meng, Y. Li, W. Wang,and J.Fu, "Experimental study on
performed to increase the sensitivity of the robot towards
leak detection and location for gas pipeline based on acoustic
extremely small leaks. Machine learning algorithms are being
method," Journal of Loss Prevention in the Process Industries,
developed and tested to make the system completely
voI.25,pp.90-102, 2012.
autonomous.
[8] L.Sun,Y.Li, T.Liu, SJin,and W.Wang, "Leak detection and position method for pressure piping using acoustic emission",
8.0
REFERENCES
[1] C. Sandberg, 1. Holmes, K. McCoy, and H. Koppitsch, "The application of a continuous leak detection system to pipelines and associated equipment,"IEEE Transactions on Industry Application,voI.25, pp.906-909,1988. [2] Y.Zhou,S.Jin,and Y.Zhang, and L.Sun,"Study on the distributed optical ber sensing technology for pipeline leakage detection," Journal of Optoelectronics Laser,voI.16,pp.935938,2005.
Proceedings of the 7th World Congress on Intelligent ContTol and Automation,pp.8425-8429,2008. [9] Daaland A. Real-time radiography for in-service inspection of exible pipeline system. Trends in NDE science and technology. Proceedings of the Fourteenth World Conference on Non-Destructive Testing, New Delhi, vol. 3; 1996. pp. 1361–1364. [10] Rihar G, Varilstvo ZA, Rant J, Stefan J. The rst application of imaging plates to an examination of welded joints.
[3] L.Yang. G.Liu, G.zhang,S.Gao, "Sensor development and
Proceedings of the Seventh European Conference on Non-
application on the oil-gas pipeline magnetic ux leakage
Destructive Testing, vol. 3(8); 1998.
detection," The Ninth International Conference on Electronic
[11] Gadelmawla ES, Elewa IM. On-line measurement of
Measurement & Instruments,pp. 2-876 - 2-878,2009.
product dimensions using computer vision. Proceedings of
[4] Shuaiyong Li, Yumei Wen*, Ping Li, Jin Yang, Lili Yang. “Leak
nineth IMEKO Symposium Metrology for Quality Control in
Detection and Location for Gas Pipelines U sing Acoustic
Production Surface Metrology for Quality Assurance, Cairo,
Emission Sensors”, IEEE International Ultrasonics Symposium
Egypt, vol. 4; 2001. pp. 1–10
Proceedings, pp. 957-960, 2012
[12] Gadelmawla E, Elewa I, Soliman H. Assessment of surface
[5] W.A Wassef, M.N. Bassim, M. Houssny Emam and K. Tangri.
texture using a uniquely featured computer vision technique.
(1984). Acoustic emission spectra due to leaks from circular
Society of Manufacturing Engineering, Fourth International
holes and rectangular slits.
Machining & Grinding, Troy Michigan; 2001. pp. MRO1–23
September 2017
Simplifying Phased Array Ut Process with Digital Solutions and Wireless Collaboration Anandamurugan Subramanian, BHGE Inspection Technologies, JFWTC, Bangalore, India Email : anandamurugan.s@bhge.com 1.0
INTRODUCTION
F
or decades, the industry has improved productivity and efciency, reducing costs to maintain their most critical industrial assets using Non-Destructive Testing (NDT) hardware and software. These traditional inspection technologies are poised for disruption through new services for connectivity and digital inspection, which will unlock tremendous value for asset owners, OEM’s and service providers. In an industry climate driven by today’s oil prices, an aging workforce and increasingly complex industrial assets and inspections, it is critical to improve operational efciency. Today’s most advanced inspection technologies such as phased array ultrasound and digital x-ray are rmly part of the digital industrial age. Derived from healthcare and hardened to stand up to the toughest eld conditions, these techniques help to detect corrosion, erosion, weld failures and other indications before they turn into costly downtime. Armed with these tools, inspectors generate large volumes of digital inspection data which can be viewed in real-time, centralized, analyzed and archived, and shared. Phased array ultrasound technology is now widely used across industries for Non-Destructive Evaluation. According to Markets And Markets research: The ultrasonic testing (UT) market is expected to reach USD 3.93 Billion by 2022, at a CAGR of 8.3% between 2016 and 2022. The factors which are driving the growth of market include development of portable phased array ultrasonic testing equipment, need for reliable nondestructive testing technique for berglass and carbon ber composites in manufacturing, growth in ultrasonic testing services market, and government mandates. Even though phased array ultrasonic testing technology is wide-spread across the world, appropriate training is extensively needed to understand the product operation and clear instructions, checklists are needed as document to perform inspection as per the inspection expectations from experts to perform inspection with high degree of accuracy and precision. Today’s NDT and inspection managers face a complex and everchanging environment, including: Ÿ Increasing complexity of inspections Ÿ Loss of domain expertise from departing or retiring inspection experts Ÿ More demanding codes and standards Ÿ Constant drive for improved detection and productivity Ÿ Pressure to reduce asset downtime September 2017
NDT industry has begun the journey toward more reliable, connected and smart inspection hardware and software. One way to address this issue is using advanced technology, giving inspectors the tools and resources they need. Designing the phased array ultrasound products, with the features and functionalities they share, help organizations embrace the industry shift toward digitization, improve inspection productivity, contribute to long-term equipment reliability. With the modernized digital transformation adding inspection procedures, training, demonstration videos, help documents and drawings can be built into inspection devices and provide step-by-step procedures or embed a demo video. Guided & Customized “apps” — Digitizing the Inspection procedures, training, demonstration videos, help documents and drawings and built into inspection devices will change the way inspection is done or prepared for the inspection. This improves consistency and reduces training costs. Instead of asking the inspector to guess about how to conduct an inspection, by providing the step-by-step procedures or embed a demo video. l
Intuitive User Experience (UX) — Just like your smartphone, operating an ultrasound device just makes sense, and interface features are common across devices. Rather than adjusting manual dials or buttons, navigating ultrasound device like smartphone will be fast, easy and intuitive for inspectors at all levels. Selecting, dragging and scaling screen features is easy, and reduces levels of awkward and confusing analog menus. l
Wireless connectivity — With the modernized technology connecting devices with internet will make lot of operations easier for the user. Instruments with standard onboard Wi-Fi will provide secure wireless connectivity streamlines reporting and analysis, makes software upgrade service and enables real-time remote collaboration with off-site experts. If the technician needs a second opinion, instant service via remote collaboration will improvise the inspection process and reliability to greater extent. l
2.0 GUIDED & CUSTOMIZED “APPS” Digitizing the Inspection procedures, training, demonstration videos, help documents and drawings by building into inspection devices can improve consistency and reduces training costs. Reecting author’s expectation for the application solution in a UT “app” as how we prepare power point slides for the presentation will improve the inspection process for both the author (or Level III) of the application and the inspector who performs the inspection. Examples of the “App on Device” concept for different phased array UT applications and its solution to overcome the challenges are discussed ahead.
2.1 Corrosion Inspection Phased array ultrasonic inspection for corrosion on pipes, tank bottom and on other complex surfaces increases productivity and provide more data points compared with conventional (a) (b) thickness gauge data. For the accuracy of thickness, specially designed phased array UT probe can be used to detect near surface indication and hence able to measure the thickness nearer to the scanning surface. Dual Element Array (DM) probe is designed with the array of elements which is used for transmission and another set of elements which is used for receiving. The required effective area of virtual probe can be congured by grouping the array of elements as it is inevitable with Phased Array UT. DM array probe will give the performance like conventional TR Dual probe. To perform the required calibrations and the setup for corrosion inspection using phased array technology is not straight forward. Hence, creating the “app” with all the inputs needed which will guide the user to verify the list of items needed for the inspection, perform the required calibrations and perform the inspection on actual job will enhance the inspection preparation and reduce the day to day documentation like worklist. Figure 1 shows how the digital checklist can be prepared for the list of materials needs to be collected for the eld inspection.
block for calibration and scanning as shown in gure 2. (a)
(b)
Fig 2a: Step by step guidelines Fig 2b: Expert app for 2-Point ( l e f t ) t o p e r f o r m 2 - p o i n t calibration with no instructions calibration
With this “app”, the users will realize the simplicity of “app on device” concept and learn the application faster as how to do the calibrations and scanning of demo block. Expert (Corrosion DM app) “app” is created with no instruction as shown in gure 2b as its designed for the trained user to use this app to congure the setup for the inspection. Every application solution will have written procedure which will be used as reference to design the day to day work list.
Fig 3b: Demo app created with Fig 3a: Inspection setup for cross-section of corrosion block demo block scanning and its C-scan
Cross-sectional image of corrosion demo block as shown in gure 3a and 3 b gives the instant access to replicate the data in C-scan which will increase the condence of the user. Inspector or the experts will refer the inspection procedure is lot of instances during inspection or for inspection planning. So, adding the soft copy of inspection procedure as part of “app” will be easy for the user to verify the procedure from instrument “app” itself in case of any reference is needed for the inspector. Fig 1: Digital List of Material - Checklist for corrosion inspection
Two “apps” that can be created at 2 different level as shown in gure 2a and 2b to differentiate the guided and expert “app” and highlight the “App on Device” concept. The guided or demo “app” can be used by the starters which will guide the user on every page to complete the inspection successfully with reference to the images, guidelines and videos. The expert “app” can be used by the experts who can use the “app” with minimal inputs but focused on UT settings as per the part geometry and material characteristics. The picture 2a and 2b shows the difference between guided & expert “app” to achieve the inspection of corrosion with expected accuracy and precision. Author of these “apps” has designed with proper guidelines and hence the user can accomplish the raster scanning of corrosion demo block with xed scanner can be done faster with very minimal training. Corrosion demo block is designed to demonstrate the capability of detecting the corrosion defects like pitting. The “app” has been created with pictures of demo
Figure 4: Digital corrosion inspection procedure embed in the “app”
2.2 Composite Inspection Composite inspection can be done effectively using the exible interface to adapt the surface irregularities. Phased array UT probe which is designed with exible interface and hence the probe can be adapted on any surface and perform inspection. The challenge with exible interface is the setting of interface gate as shown in gure 5a and then to apply the proper calibration. Hence creating a “app” with the guidelines of how to easily setup interface gate will avoid the confusion on interface gate September 2017
setup and makes it easy. If user can be provided with the document to refer as how interface gate functions as pdf document as shown in gure 5b in the “app” then user doesn’t need to worry too much about instrument operations and setup.
Even though the phased array ultrasonic testing of weld inspection technique is same, how to use the complex mechanics of probe and scanner assembly on the boiler tube is a challenge. To overcome the complexity of this operation, a video of how to operate this scanner and mechanics with “app” as shown in the gure 7 will greatly help the user to refer mechanics operation at any time which will minimize the burden on longtime training to know the operability of scanner and its mechanics.
Fig 5a: Step by step guidelines Fig 5b: PDF le added in the to setup the interface gate as “app” to explain the interface per the author’s word gate working principle
So far, the instrument software had given the option of predened layouts for the user to select them as per the inspection need. In some applications instrument provided layouts may not exactly fulll the author’s (or Level III) expectation to organize the data views. If the instrument software can provide the ability to create the layouts or to align the data views (i.e., S-scan, Cscan, B-scan, A-scan etc.,) as per author’s imagination it will make the application solution better. In the gure 6 the layouts are designed by the author to track the backwall (using Gate B) and the material region (Gate A). The layout is customized with 4 C-scans as per the composite inspection need. Customized parameter which is needed for the inspection process that can be directly accessible on the screen as shown in gure 6 will help the inspector by directly using them instead of searching for the parameter hiding under the wizard or menu list.
Figure 8: Instruction to perform encoder calibration using PALM Scanner on Boiler Tube
Another complexity is the encoder calibration on the eld due to the scanner design and mechanics. The setup should be attached on the reference block or on the actual tube for encoder calibration. Hence the customized image as shown in the gure 8 as how to perform encoder calibration will simplify the inspector’s job of performing encoder calibration. (a)
(b)
Fig 6: C-scan of composite block using RotoArray probe
2.3 Low Prole Weld Inspection Weld inspection on boiler tube is a challenge with radiography due to accessibility and large volume of welds to be inspected in limited time. Phased Array UT (PAUT) is another best option to inspect the tube weld. It has an advantage of good Probability of Detection (POD), image recording with 3-dimensional data on Top, Side and End Views with overlay for easy decision making. Though the technique is powerful and efcient to inspect welds, there is a challenge on mechanics. The scanner and probe are designed with low prole due to the limited space constraints.
Fig 7: Screenshot of video playing the PALM scanner operation as instruction for the operator
September 2017
Fig 9: Boiler tube weld inspection setup and data ( c)
Figure 9 shows the complete setup of boiler tube weld application and its sector scan & C-scan image with weld overlay using the “app” created for this inspection solution. 2.4 Glue line and seam inspection for automotive body panels Adhesives are being increasingly used as a joining technology for automotive body panels including edge and non-edge joints. Total accumulated length of glue lines can reach hundreds of meters per automobile body. Like other automotive joining processes, adhesive bonding may not provide 100% process reliability. To identify areas with lack of adhesive as well as misaligned bond lines, destructive or nondestructive testing is necessary.
‘Bond Seam Scanner’ is easily clamped on body panels joined by a seam or other adhesive bonding process. The design enables the array to adopt to contoured parts commonly used in automobile designs. Adhesive bond lines up to 32 mm width can be inspected. A spring-loaded encoder wheel provides a stable inspection platform and tracks the sensor position. A protection foil minimizes the need for couplant and enables manual scanning. In this application, the challenge is to perform the inspection of car doors in sequence for mass production in automotive industry. So, the chances of inspecting the wrong side of door is high due to the fatigue of inspector. Hence the “app” is intuitively customized by adding the picture of door and highlighted the side A, B and C on each panel to inspect the doors. Always a visual feedback will help the inspector to perform better and reliable. This app will reduce the chances of error due to the customized guideline and UI designed for the bond seam application as shown in the gure 10a and 10b.
inspector who nds a severely corroded section of piping on an offshore oil rig, and is unsure whether to take the unit out of service. In an analog world that inspector might have been forced to make a judgment call, or at best y in an expert via helicopter for consultation, incurring costly delays. Today that inspector can connect wirelessly to an onshore expert who can view a live stream directly from the inspection device, providing guidance and recommendations for additional further inspections, helping to make the right call. Real-time streaming makes it possible to reduce costs and improve workforce training in many situations.
Fig 12: Connected solution for more condent decisions
Fig 10a: Inspection setup
Fig 10b: Red box on door instructs the area to be inspected
3.0 Intuitive User Experience (UX) Another residual factor with the users of phased array ultrasonic instrument is how to use the tools in instrument. Ensuring the inspector’s expertise is focused on the work they are doing, not on the product they are using will make the inspector’s job easier and more productive.
Figure 11: User experience of inspection device
Like how the smart phones have evolved with user experience, designing the product with ease of touch operation without the aid of mouse or buttons or any hard keys can enhance the inspection instrument user experience. With the intuitive UX user doesn’t need to worry about how to operate the tools using buttons, menu and parameter. User can just operate the tools in the same fashion as how a person operates the smart phone. Automatic setup like range, gates and other UT settings for calibration and inspection will help the operator to just input the signicant parameter needed. 4.0 WIRELESS CONNECTIVITY One of the most exciting technologies available today enables real-time streaming and remote collaboration. This technology will experts the ability to participate in live inspections anywhere in the world via wireless connection. Imagine an
For inspection service providers who manage large eets of inspection equipment, digital inspection tools are boosting productivity. Imagine being able to deploy digital procedure updates and work plans to a large eet of inspection hardware and technicians in multiple cities at the push of a button, or centralizing inspection data management and reporting for your company. Imagine a situation wherein instant guidance is needed for the inspector by supervisor and due to limited space constraint (i.e., scaffolding, rope hanging, man hole accessibility etc.,) only one person can see the instrument but the supervisor guidance is mandatory. Instant desktop sharing via Wi-Fi as how smartphone works (i.e., apps are designed to see the screen of television in the phone) will help the inspection process. The supervisor can use the tablet or smartphone who can instantly see the screen hold by inspector and provide guidance. 5.0 CONCLUSION As the Phased Array Ultrasonic Testing is growing rapidly for wide variety of applications, it’s also important to simplify the process of operating the instrument. Since every application needs a unique inspection solution (i.e., it can be ultrasonic technique or probes or scanner or user experience etc.,), it’s very difcult and complex for the inspectors to get updated with every solution. Hence specialized “apps” design will help the user to guide the operation and simplify the training for the unique application solution. Pre-planning “app” design software like “Mentor Create” from BHGE Inspection Technologies can bridge the gap between the expert’s innovation and inspector workow operations. With the new phased array ultrasound instrument – “Mentor UT”, new “apps” have been created for different application which provides instruction and ease of operation with customized UI tailored as per the application needs. Mentor devices are designed by the team of experts and engineers who work to September 2017
understand the challenges inspectors face and nd innovative
REFERENCES
ways to build the “smarts” into the instrument to help make the inspector’s job easier.
[1] GE Inspection Technologies, https://geinspectiontechnologies.wordpress.com/tag/mentor-
Besides all the advantages of app based concept and ease of
ut/
operation, if a technician does not understand a step or a data signal, he or she can push a button on the device and wirelessly
[ 2 ]
stream their inspection to the PC, phone, or tablet of a remote
h t t p : / / w w w. m a r k e t s a n d m a r k e t s . c o m / M a r k e t -
expert. The advancement of digital eld and adapting the digital
Reports/ultrasonic-testing-market-131229239.html
M a r k e t s A n d M a r k e t s ,
technology in inspection eld will help the industry to become more reliable, efcient and more connected. The
[ 3 ] B H G E I n s p e c t i o n Te c h n o l o g i e s ,
Inspectionworks platform from BHGE Inspection Technologies
https://www.inspectionworks.com/#/supportDetails/mentoru
offers eet management and analysis tools that make data
t
search, storage, analysis and sharing easy in a secured environment for inspection teams of all sizes. Mentor devices
[ 4 ] B H G E I n s p e c t i o n Te c h n o l o g i e s ,
can be connected to tablet or smartphone using Wi-Fi hotspot
Mentor_UT_Users_Manual.pdf
even without internet and share the screen using desktop sharing option with the supervisor tablet or smartphone who
[5] Anandamurugan S, Ultrasonic Phased Array Technology for
can instantly see the screen and provide guidance.
Enhanced POD & Inspection Speed in Corrosion Detection and Wall Thickness Measurement, APCNDT 2013
These new technological developments are making it possible to realize the benets of phased array ultrasonic inspection on a
[6] Anandamurugan S, Phased Array UT Application for Boiler
global scale and taking the complex solutions into simplied
Tube Inspection in Manufacturing and In-Service, APCNDT
approach using the power of digital evolution.
2013
September 2017
Study of Distortion of Low-frequency Axisymmetric Ultrasonic L(0,2) Guided Waves in Pipe Bends and Elbows M Venkata Sai Siva Ramakrishna*, Radhakrishna Korlam*, Harikrishnan A S**, Renjith P**, Tarun Kumar Mishra**, Krishnan Balasubramanian* *Centre for Non Destructive Evaluation, IIT Madras **Detect Technologies Private Limited ABSTRACT The use of ultrasonic guided waves in long range pipeline monitoring is restricted to straight sections, especially in pipes of larger diameters. However, there have been recent studies on the propagation of these waves through bends of different angles and bend radii. The transmission coefcient and velocity characteristics of the wave at pipe bends have been studied for pipes of lower radii (typically 3-8 inches nominal pipe diameter). This paper studies the wave front changes primarily in pipes of larger diameter (~24 inches nominal pipe diameter). 3D nite element simulation has been done on commercial software to understand the L (0, 2) wave behaviour at the bends, and the shift in the wave front is experimentally validated using GUMPS (Guided Ultrasonic Monitoring of Pipe Systems), an MsS Technology for pipeline corrosion monitoring; developed and owned by Detect Technologies. The study shows that the wave tries to move at a constant velocity and hence gets distorted at the farther region of the bend from the Centre of curvature, thus resulting in an angled, elliptical wave front from the original circular wave front. 1.0
INTRODUCTION :
T
he interaction of low-frequency axisymmetric ultrasonic guided waves in bends has already been studied [1] to understand the transmission and reection of the incident wave as it passes through the bend, for different bend angles and bend radii. The propagation of guided waves in straight pipelines is well understood and used widely for corrosion inspection in pipelines in industries such as oil and gas [2-8]. Although there have been recent developments to use guided wave sensors for monitoring across elbows, a reduction in POD is observed and the signals appear to be erratic beyond the elbow. [9-17] . The fundamental problem of using existing sensors across bends is that bends can result in the dispersion of guided waves and hence signals from any defect in the region may get masked by the dispersed signals. [1] However, this study reveals that in pipes of larger diameters, the dispersion is not the major concern as much as the distortion of the wave front. This study reveals distortion of the wave happening in the outer region, with the possibility of a blind spot in the inner region of the pipe bend. An understanding of this is crucial in the development of guided wave LRUT inspection tools. This paper is organized as follows. The rst section of the paper presents the dispersion plot of a 24-inch nominal size, standard industrial pipe (on which the experiments and simulation was conducted). This section describes the possible wave modes that are generated and the group velocity of these waves. The second section presents the results of the simulation.
The third section describes the experiment designed to validate the simulation results. And nally, the paper concludes with inferences from this study and the scope of future work. 2. 0 BACKGROUND This study is conducted on a pipeline of OD 609.60 mm and pipe thickness of 5.537 mm (24 inches nominal pipe size SCH 5s Mild Steel Industrial pipe). It is seen (from simulations) that the pipe material does not affect or change the behaviour of these waves and hence the phenomenon applies in general to pipes of any alloy compositions, although the validation is performed only on a mild steel pipeline for practical reasons. A standard 90º elbow of 24 inches is welded onto the straight section and the study is done by placing GUMPS transducers on the elbow region and the straight region. For L (0, 2) mode guided wave analysis of the pipe, a frequency of 90 kHz was chosen for its non-dispersive nature in that frequency region, as shown by the dispersion plot below. An in-plane 3-cycle Hanning window burst is applied at the transmitter side, uniformly throughout the angular positions to result in a circular wave front L (0, 2) wave mode. To understand the distortion of the wave front that occurs at the bend, GUMPS-array receiver probes are placed at different angular positions of the pipe along the elbow. The simulations are conducted keeping in mind the same boundary conditions , i.e. uniform circumferential excitation to generate a circular wave mode and probe points at different angular positions to monitor the received signal. Wave visualization was also done using simulations to get a better understanding of the distortion occurring at the bend. September 2017
4. RESULTS 4.1 Finite Element Simulation Results :
Figure 1 : Dispersion curves for a 24 inch MS pipe.
Figure 3 : Visualization of Von Mises Stress in the axial direction over increasing time steps (initial timestamp is shown by subgure 1 and the time steps increase all the way till subgure 5)
Figure 2 : Schematic of the pipe setup used for experimental validation 3.0
METHODS
3.1 3D Finite Element Simulations The model is a straight-bend-straight pipe. A fully 3 dimensional time transient simulation is conducted using Solid Mechanics Module COMSOL. The meshing is quadrilateral in the straight regions and tetragonal in the bend to capture accurately simulate mode conversions. Maximum meshing size is set as 1 mm meaning 6 divisions of thickness allowing for study along the thickness. Meshing size is chosen according to the frequency and wave speed. The time step is chosen as 1E-8 s and the simulation is conducted for an interval of 0 to 1 ms. Axisymmetric L (0, 2) mode excitation was achieved by giving a uniform longitudinal force along the axis at one end of the pipe. A 3-cycle Hanning pulse window entered around 90 kHz was used for excitation. Material of Steel Having the modulus of elasticity E = 210 GPa, density ρ=7800 kg/m3 and Poisson ratio ɳ = 0.303 were specied. 3.2 Experimental procedure In order to validate the FE simulation results, laboratory experiments were performed using Mild Steel pipes of 610 mm OD and 598.926 mm ID and of geometry as shown in gure 2. The experiments were conducted using GUMPS, a novel MsS Transducer developed by Detect Technologies. The transducer was excited in the axial (in-plane) direction through a 3 cycle Hanning windowed tone burst with a centre-frequency of 90 kHz generated by a RITEC 4000 pulser-receiver (Ritec Inc., USA). The excitation was given symmetrically using strips of 10 cm length made of iron-based magnetostrictive material, bonded axially at symmetrical positions around the pipe. The receivers were made using similar strips of 10 cm length, bonded circumferentially at symmetrical positions around the pipe. The signals generated were then received at 7 different angular monitoring points, the rst along the longer part of the bend and at different clock positions in sequence till the last one along on the shorter part of the bend, as shown in Fig. 2 using an Agilent DSO 7012B digital storage oscilloscope (Agilent Technologies, USA). September 2017
Figure 4 : Schematic of the setup used for simulation. The 3 Probe point sets used are marked in the gure
Figure 5: A plot of the stress peaks at different clock positions vs the time at which they are recorded by the probe point. The wave front before it hits the pipe bend is fairly straightforward to understand. The peaks of stress are in line (as shown by the red line in the plot) and form a circle (along the cross section of the pipe). The peak amplitudes are also more or less the same (as shown by the blue line). Therefore, the uniform source stress distribution is maintained along the straight section of the pipe. The wave gets distorted at the elbow, with the peak stress of the wave getting concentrated at the 12 o’clock o position as it reaches the mid point 45 region of the elbow (where probe set 3 is marked in figure 4), as shown by the blue line. Also the wave front of (the now varying-amplitude) peaks is tilted (and hence of ellipsoidal cross section) with the peaks reaching earlier along the shorter 6 o'clock position as shown by the red line.
As the wave crosses the 45o part of the elbow, the wavefront begins to rotate around the circumference, with max amplitude stress roughly reaching the 9 o’ clock position at the end of the elbow. The stress approaches near uniform distribution again as it traverses along the the second straight section of the pipeline after the elbow.
Figure 6: Plots showing how the stress concentrates at one point of the elbow and starts rotating (in a helical fashion) after the 45º point of the elbow.
4.2 Experimental Results
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Figure 7: Experimental plot of the stress peaks at different clock positions vs the time at which they are recorded by the receivers. Due to the limited test bench setup, the end wall reection is used to see the behaviour of the distorted wave.
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Figure 8: Experimental plots of the amplitude variation with clock position for different indications (at different receiving points.
5. 0 CONCLUSION Comparing Figure 7 and Figure 5, it is evident that the time delays of the peak stresses that were estimated in the simulation did not match with the experimental cases. This could be due to the fact that the creation of a perfect cylindrical wave at source (transmitter) could not be achieved. However the results of the stress concentration that occurs at the elbow and the helical rotation of this stress as simulated by gure 6 closely resembles the experimental results obtained by the array-GUMPS receivers R1 and R2 (shown in schematic in gure 2) as shown in gure 8. These results provide insight on how a particular defect in an elbow could be missed if it lies in the position of low stress concentration and hence work on controlling this distortion of the guided wave would be crucial in creating advanced LRUT systems capable of inspection beyond elbows and in the elbow itself.
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6.0 ACKNOWLEDGEMENT: The authors would like to thank inspection engineers at Detect Technologies, Mr. Madan Raaj and Mr. Dhanapal Natarajan for promptly helping with the collection of experimental data. 7.0 Ÿ
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REFERENCES
Bhupesh Verma, Tarun Kumar Mishra, Krishnan Balasubramaniam, Prabhu Rajagopal, “Interaction of lowfrequency axisymmetric ultrasonic guided waves with bends in pipes of arbitrary bend angle and general bend radius”, B. Verma et al. / Ultrasonics 54 (2014) 801–808
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M.H. Park, I.S. Kim, Y.K. Yoon, Ultrasonic inspection of long steel pipes using Lamb waves, NDT and E International 29 (1) (1996) 13–20. H. Kwun, K.A. Bartels, Magnetostrictive sensor technology and its applications, Ultrasonics 36 (1) (1998) 171– 178. J.L. Rose, D. Jiao, J. Spanner Jr., Ultrasonic guided wave NDE for piping, Materials Evaluation 54 (11) (1996) 1310–1313. H.J. Shin, J.L. Rose, Guided wave tuning principles for defect detection in tubing, Journal of Nondestructive Evaluation 17 (1) (1998) 27–36. M.J.S. Lowe, D.N. Alleyne, P. Cawley, Defect detection in pipes using guided waves, Ultrasonics 36 (1) (1998) 147–154. [11] H.J. Shin, J.L. Rose, Guided waves by axisymmetric and non-axisymmetric surface loading on hollow cylinders, Ultrasonics 37 (5) (1999) 355–363. M.J. Quarry, J.L. Rose, Multimode guided wave inspection of piping using comb transducers, Materials Evaluation 57 (10) (1999) 1089–1090. D. Alleyne, B. Pavalkovic, M. Lowe, P. Cawley, Rapid longrange inspection of chemical plant pipe work using guided waves, Insight 43 (2001) 93–96. J.L. Rose, X. Zhao, Flexural mode tuning for pipe elbow testing, Materials Evaluation 59 (2001) 621–624. J.L. Rose et al., A natural focusing low frequency guided wave experiment for the detection of defects beyond elbows, Transactions of the ASME – Journal of Pressure Vessel Technology 127 (3) (2005) 310–316. H. Nishino, K. Yoshida, H. Cho, M. Takemoto, Propagation phenomena of wideband guided waves in bended pipe, Ultrasonics 44 (2006) 1139–1143. T. Hayashi, K. Kawashima, J.L. Rose, Calculation for guided waves in pipes and rails, Key Engineering Materials 270–273 (2004) 410–415. T. Hayashi, K. Kawashima, Z. Sun, J.L. Rose, Guided Wave Propagation Mechanics Across a Pipe Elbow, Transactions of the ASME – Journal of Pressure Vessel Technology 127 (3) (2005) 322–327. K.E. Rudd, K.R. Leonard, J.P. Bingham, M.K. Hinders, Simulation of guided waves in complex piping geometries using the elastodynamic nite integration technique, The Journal of the Acoustical Society of America 121 (3) (2007) 1449–1458. H. Nishino et al., Experimental investigation of mode conversions of the T (0, 1) mode guided wave propagating in an elbow pipe, Japanese Journal of Applied Physics 50 (4) (2011) 046601-1–046601-7. S. Furuhashi, K. Sorimachi, T. Sugiura, Change in Mode Congurations and Propagation Velocity of Guided Waves through an Elbow Section of a Pipe, in: IEEE International Ultrasonics Symposium Proceedings, 2010 pp. 2211–2214. A. Demma, P. Cawley, M. Lowe, The effect of bends on the propagation of guided waves in pipes, Transactions of the ASME – Journal of Pressure Vessel Technology 127 (3) (2005) 328–3
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Inspection of Off-shore Structures using Remotely Operated Vehicles: Planys Experience *Vineet Upadhyay1, Manas Galipalli1 , Sanchit Gupta1, and Prabhu Rajagopal1,2 1 Planys Technologies Pvt. Ltd., IITM Research Park, Taramani, Chennai-600113, T.N., India 2 Center for Nondestructive Evaluation and Department of Mechanical Engineering, IIT Madras, Chennai-600036, T.N., India *Email : vineet@planystech.com ABSTRACT ABSTRACT Underwater structures in coastal areas (for example, ports and terminals) and off-shore platforms (for example, tanker terminals and buoy moorings) need to be inspected periodically for detecting damage and initiating maintenance activities. The conventional method of using human divers suffers from various limitations such as shallow depth reach, limited endurance and capability to carry payloads and an inherent risk to human life during poor weather conditions or when operating inside conned places. The Center for Non-Destructive Evaluation (CNDE) at IIT Madras together with spin-out company Planys Technologies has been developing compact ROVs with exible payload capacity addressing these challenges. This paper presents case studies from oneld inspections using Planys ROV Beluga, a double-hull vectored multi-thruster ROV customdeveloped for near offshore and in-land shallow-water applications. The results show the damage detection and inspection capabilities using visual and LASER payloads. This work will be of interest to offshore platform asset integrity and plant safety professionals. 1.0
INTRODUCTION
India is one of the largest crude oil importing countries in the world. Oil and Gas in the country are mainly produced in the Bombay High oil-eld development area in the Arabian Sea and the Krishna-Godavari Basin in the Bay of Bengal. Large numbers of offshore platforms situated in these regions perform excavations on a daily basis. Periodic maintenance activities are performed by trained professionals to ensure that these platforms keep functioning without any down times. Regular inspections are performed to identify any signs of weakness or damage of the structure or its sub-systems. The most challenging areas to inspect are the underwater portions of the platforms due to their restricted accessibility and availability or high costs of underwater equipment and trained divers, limitations on diving depth, poor weather conditions, poor underwater visibility and an inherent risk to human life during a diver-assisted operation. Off-shore platforms, rigs, ship propellers and internal ballast tanks also need regular maintenance and inspection for corrosion and bio-fouling. Currently, in India, inspection operations of immersed structures and ships are mostly performed by divers and offshore technicians or by third-party inspection service providers during dry docking sequences. Lives of operators are at risk in such operations which are often performed in low-accessibility or inaccessible areas where communication and endurance are limited. In addition to such constraints and risks, due to challenges in availability of service providers and operators of required technical experience, manual operation is also prone to unreliability. September 2017
This paper describes methodology for usage of Remotely Operated Underwater Vehicles (ROVs) in such scenarios which not only mitigates these risks or limitations but also provides advanced inspection capabilities. ROVs are unmanned vehicles which are controlled remotely by pilots, to perform structural inspections and hydrographic surveys of inland and coastal water regions [1, 2]. They are capable of reaching the desired location based on on-shore navigation, performing inspection in conned spaces and providing more efcient, reliable and safe inspection solutions. The paper is based on the operational and technology development experience of the authors, through an Indian Institute of Technology Madras (IITM) incubated startup company, Planys Technologies Private Limited (www.planystech.com). The paper is organized as follows. Firstly, a brief background on the traditional inspection methods and their challenges are presented while describing ROV capabilities to overcome them, followed by a concise description of features, capabilities, and typical applications of ROV Beluga developed by Planys Technologies. The further sections include a detailed description of inspection and survey methodologies illustrated through case studies from Planys experience. Finally, the paper concludes with some directions for further development and future work. 2.0 BACKGROUND The traditional method for underwater exploration or inspection dates back to ancient times where human diversould recover shells, food, pearls and sponges from the sea [3]. Today diving is a major commercial industry involving professionaL
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as well as recreational activities. Although underwater diving is beneting from continuous development of technology, a diver’s life is prone to risks such as entanglement, rough weather conditions, equipment malfunction, umbilical damage, excessive nitrogen or oxygen absorption in the body, pulmonary embolism and dangers from marine life [4]. Divers continue to face challenges in accessing conned spaces such as those in tunnels, pipeline or dams. As the diving depth increases, so do the complexity of engineering equipment, expertise required and the associated costs. ROVs were developed to perform such and more complicated tasks with higher reliability and in marine areas entirely out of human reach. ROV operation does not endanger human life as it is controlled remotely from a safe location above water surface. ROVs can perform greater numbers of activities simultaneously and with more signicant repeatability as compared to the conventional diver based inspection methodologies. Further, ROVs can be operated round the clock, provide stable live inspection data streams to the shore control station, reach greater depths, carry heavy work equipment and operate in bad to worse environmental conditions. ROVs have been widely used in the offshore industry for various activities such as drill support, seabed survey, structural integrity inspection, pipe-lay jobs, debris removal, inspection, maintenance, repair jobs and environmental surveys [5]. ROVs are further used for near shore and inland water applications such as the inspection of ships, jetties, dams and bridges. Small and portable ROVs can be efciently used for accessing locations that may be remote or have restricted accessibility such as inside long and narrow pipelines or tunnels [6, 7]. 3.0 ROV BELUGA Developed entirely in India by Planys technologies, Beluga illustrated in Fig. 1 (see Table 1 for technical specications), is a compact, modular and portable ROV that can sustain 2-4 meters of wave height, moderately rough swell, up to 1 m/s of sea currents and can dive up to 200 meters of depth. An observation class ROV, Beluga’s design has a state-of-the-art dual hull and heavy bottom hydrodynamic design, providing it with static and dynamic stability in harsh underwater environments. Beluga is equipped with eight thrusters providing control in 5 degrees of freedom along with forward thrust of 17.5 kg-f and an operating speed of 3-4 knots. The heavy bottom feature of the vehicle inhibits roll motion. Beluga also carries an Inertial Measurement Unit (IMU) for orientation feedback, a pressure sensor for depth feedback and a Global Positioning System (GPS) for position feedback on the water surface. Its modular architecture allows Beluga to carry a variety of additional payloads such as high-denition cameras, high-intensity lights, LASERs as crack measurement unit, Altimeter, Side-Scan Sonar, Ultrasonic thickness measurement unit, Cathodic Potential measurement unit, bio-fouling cleaning equipment, 2D & 3D Imaging/Scanning SONARs [8].
Fig. 1: Photograph of ROV Beluga with highlights of its features
Table 1: ROV Specications (www.planystech.com)
Beluga is suited for services in the offshore oil & gas sector, shipping industry (hull, propeller, rudder and ballast tank), ports & marine terminals, dams, power plants, thermal plants and nuclear plants, including visual and non-destructive techniques (NDT) based inspection of immersed underwater structures. Capabilities to perform detection of ooding in structural members of offshore platforms through acoustic techniques, bathymetric surveys using SONARs to study seabed topography and hydrographic surveys to characterize water properties such as conductivity, temperature, pH, dissolved oxygen (DO),turbidity and oxidation-reduction potential can be as plug-and-play payloads as per the application. Further, capabilities for cleaning of marine and bio-fouling growth from piles, ship hull and underwater structures, measurement of structural thickness and cathodic protection potentials on offshore structures are under development. September 2017
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4.0
INSPECTION CASE STUDIES
4.1 VISUAL INSPECTION Planys performs underwater visual inspection using its ROVs to analyze the supercial integrity of immersed structures. Live inspection provides a real-time video feed to the operating pilot and the surveyor. For this purpose, ROVs are mounted with multiple cameras which provide standard or high denition streams from various angles. Further, as sunlight does not penetrate beyond 15 – 20 m in clear water or 10 – 12 m in turbid waters from the surface, Planys ROVs are equipped with high-intensity lights to illuminate the inspection targets [9]. Water turbidity is a signicant factor in setting the underwater visibility which in turn affects the quality of video output. Navigation in highly turbid waters is an extremely challenging task, and thus SONAR units are deployed to navigate to the submerged inspection site. Further, in turbid areas, the ROV must be brought extremely close to the target in order to examine it visually. Such proximity to the target increases the risk of entanglement and collision especially in shallow water zones where the effect of wind-generated swell is high. ROV cameras are often augmented with features such as optical zoom, auto-focus, auto-iris, low light visibility and image stabilization. Often a laser scaling payload is attached to the camera to help determine the dimensions of the objects seen in the video. 4.1.1 Case Study 1: Visual inspection of piles of an Offshore Tanker Terminal Planys Technologies conducted an underwater visual inspection of 52 supporting piles of an offshore marine tanker terminal facility and expansion loops of a pipeline trestle connected to the shore, shown in Fig. 2. The terminal is located in an open area on the eastern Indian coast around 1.5 km away from the shore at Karaikal, Puducherry Union Territory with an average water depth of 12 m. Due to the shallow depth and wave action, the visibility in the region was observed in the range 1 – 1.5 m at the surface and 0 m beyond 8m depth.
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Fig. 2: A photograph of piles investigated in Case study 1 (a) at the pipeline trestle and (b) at the terminal facility
The operations were carried out over three and a half days during daytime averaging to 14 piles scanned per day from two diagonally opposite angles each. The inspections were conducted using Planys’ ROV Beluga with 120 m of tether length, one high denition 720p 50 FPS frontal color camera with two scaling LASERs, a standard denition 30 FPS bottom looking color camera and an altimeter. The ROV control console was set up at three different locations, sequentially, on the terminal platform, to access all the piles from at least two angles. The operations crew, as shown in Fig. 3, consisted of one supervisor, one winch operator and two ROV pilots with additional supporting staff provided by the terminal authorities. Many difculties were faced by the ROV pilots due to swell induced oscillations, near zero visibility closer to the September 2017
seabed and challenges faced during launch and recovery process. Since a crane facility was unavailable at the site, a sh trawler was provided to assist the manual launch and recovery of the 50 kg weight ROV.
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Fig. 3: Photograph of (a) ROV pilots at work on their portable control console and (b) ROV Beluga being launched manually from boat deck, for investigation described in case study 1
The inspection results showed signicant marine growth on the piles. The section of piles above the water surface was also found to be heavily corroded. In some piles, major cavities were observed due to localized corrosion over prolonged periods. Data Processing and Report Creation:Planys team processes the data in multiple stages [10] before delivering it to the client through a rich and interactive software interface also called as the Planys Assessment Dashboard (PAD). At rst, the raw data is cropped to meaningful sections, followed by ltering and tagging of the data points. Inspection videos are rendered with overlaid metadata such as depth, sensor measurements, altitude, date, dive number and inspection index. Planys further processes the images and videos to enhance their quality in case of recordings done in low visibility conditions as shown in the Fig. 4 below.
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Fig. 4: Enhanced images showing a processed rectangular region of interest with more clarity than the surrounding strip: (a) a section of a pile & (b) a dam wall
Haze removal algorithms are used to enhance videos or images recorded in turbid waters with low visibility. Similarly, color correction is performed to remove the extra blue or green tinge added to the videos by the surrounding water. Fig. 4(a) shows a section of a pile enhanced with Haze removal method whereas Fig. 4(b) shown a picture of dam wall normalized using color correction. A highly interactive and user-friendly software platform (software report) is developed to access the processed data, images and videos of inspection. Fig. 5(a) is a snapshot of the software report which depicts the area covered in inspection and locations of defects using a Computer-Aided Design (CAD) diagram of the structure. Images and videos of the inspection are made accessible to viewers in software report as shown in Fig. 5(b). These results helped the client site engineers gain vital information regarding marine growth and structural integrity of the immersed portions of the piles. 4.1.2. Case Study 2: Visual inspection of Single Buoy Mooring (SBM) A Single Buoy Mooring (SBM) is a oating buoy anchored at an
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4.2 ULTRASONIC THICKNESS MEASUREMENT Determining the structure’s thickness is crucial for analyzing structural deterioration which helps in determining further usable lifespan and ultrasonic NDT is widely used for this purpose [11].
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Fig. 5: (a) and (b), Snapshots(b)of Planys’ interactive software report user interface
offshore location to allow Oil & Gas tankers ofoad their cargo thorough interconnects running from the SBM to an onshore storage or processing unit. Planys conducted a visual inspection of an SBM off the coast of Kochi, Kerala India, in April 2017, photographs of which are shown in Fig. 6.
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Fig. 6: Photographs of (a) ROV Beluga approaching the SBM and (b) ROV Pilot along with the support crew positioned on the deck, for investigation in case study 2
The operations were carried out from a Diving Support Vessel (DSV) using a 4-membered crew from Planys and additional support from the onboard diving team. The operations were carried out during daytime over two days, recording two dives of 4 hours each. The objective of the inspection was a visual examination of the Buoy Underside, six Catenary Mooring Chains holding the buoy, the Bend Restrictor, Hose Connector and the Anchor Chain Connectors. Snapshots taken from the visual inspection are shown in the gure 7.
4.2.1 Case Study 3: Support Beam Inspection Planys conducted an underwater ultrasonic inspection of submerged supporting beams of the operating platform in an indoor wave ume. The inspection was focused on obtaining thickness measurements of the structural beams of the platform at multiple locations using a compact ultrasonic thickness measurement unit with a probe frequency of 2.25MHz, mounted on ROV Beluga. The operation was carried over half a day, inspecting ve supporting beams, taking measurements at different locations varying over depth. The ultrasonic thickness measurement unit was initially calibrated with a construction material sample. Subsequently, the unit and an electric spot-cleaning system (brush-type) [12] were mounted on the ROV and deployed for inspection in the wave ume. Before performing the thickness measurement, it is essential that the surface is clean enough for the ultrasonic probe to make an appropriate contact with the metal surface. Incorrect contact of the probe with surface results in inaccurate or no measurement. The targeted areas were cleaned with the spot-cleaning system controlled remotely by the ROV pilot. Then, the thickness measurements were taken using the ultrasonic unit by making an appropriate contact, as shown in Fig. 8. To perform the inspection the pilot uses live visual feeds from the cameras which are mounted on the ROV in such a way that the payloads (ultrasonic thickness measurement unit and cleaning system) are visible in the eld of view, and real-time readings of the thickness measurements are made visible to pilot in a graphical user interface. The water depth at which the thickness measurements were taken was obtained using a depth sensor onboard the ROV. (a)
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Fig. 8: A photograph of ROV Beluga (a) cleaning the structure using spot cleaning equipment and (b) performing ultrasonic thickness measurement, for investigation described in case study 3 ( c)
Fig. 7: A photograph of (a) various catenary chains and the connecting hoses from buoy underside, (b) anchor chain connector and (c) the underside of buoy, obtained in inspection performed by Planys as described in case study 2
There are several essential prerequisites to the inspection such as selection of suitable probe based on the inspection requirements, pre-inspection calibration of the probe, cleaning of immersed metal structures before taking the measurement, ne control of the ROV to make gentle contact of the ultrasonic September 2017
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The inspection results as shown in Fig. 7, showed the presence of signicant marine growth on the structures. However, no alarming structural anomalies were found. The visibility underwater at the site was greater than 5 meters which allowed the ROV to take clear and distinct images & videos of the SBM. The presence of large swell and strong surface currents made it extremely challenging for the pilots to control the ROV as desired.
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probe with the metal surface to avoid any damages to the probe, and provisions for real-time measurements, data acquisition and data visualization to the pilot or surveyor 5. CONCLUSIONS AND FUTURE WORK The paper described various inspection methodologies offered by Planys Technologies Private Limited, an Indian Institute of Technology Madras (IITM) incubated startup, using their product ROV Beluga. Advantages of ROV inspection over traditional methods were discussed. Technical details of the ROV are also presented. Further, case studies elaborating various capabilities including visual and ultrasonic inspection, video enhancement and surface preparation are discussed. Limitations and challenges with different inspection methodologies and in different operational environments have been highlighted. Planys is consistently working to increase the capabilities of its ROVs. Advanced power supply and propulsion system with improved hydrodynamics and control system are being developed to operate ROVs in challenging offshore environment. Underwater inspection capabilities are being developed to perform underwater proximity based ultrasonic thickness measurement, ooded member detection, concrete integrity inspection, cathodic potential measurement and multi-beam SONAR surveys. Further, development of marine growth removal technology using ROVs is also in the pipeline. A new ROV segment is being developed for inside pipeline inspections up to 2 km length. 6.0 ACKNOWLEDGEMENT The lead authors would like to thank Mr. Antony Jacob Ashish, NDE Lead at Planys Technologies Pvt. Ltd., for help with technical discussions and language used in the paper.
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7.0 REFERENCES [1] J. Yuh, Design and Control of Autonomous Underwater Robots: A S u r v e y, K l u w e r A c a d . Pu b l . 8 ( 2 0 0 0 ) 7 – 2 4 . doi:10.1023/A:1008984701078. [2] L. Whitcomb, Underwater robotics: out of the research laboratory and into the eld, Proc. 2000 ICRA. Millenn. Conf. IEEE Int. Conf. Robot. Autom. Symp. Proc. (Cat. No.00CH37065). 1 (2000) 709–716. doi:10.1109/ROBOT.2000.844135. [3] Research Repositor y. Rubicon. 2011. Available online h t t p : / / a r c h i v e . r u b i c o n foundation.org/xmlui/bitstream/handle/123456789/5894/SPUMS_V5N2 _2.pdf?sequence=1 (last accessed: 24 Oct 2017) [4] R.. Murphy, E. Steimle, M. Hall, M. Lindemuth, D. Trejo, S. Hurlebaus, Z. Medina-Cetina, D. Slocum, Robot-assisted bridge inspection, J. Intell. Robot. Syst. Theory Appl. 64 (2011) 77–95. doi:10.1007/s10846-0109514-8. [5] A. Shukla, H. Karki, Application of robotics in offshore oil and gas industry— A review Part II, Rob. Auton. Syst. 75 (2016) 508–524. doi:10.1016/j.robot.2015.09.013. [6] R. Montero, J.G. Victores, S. Martínez, A. Jardón, C. Balaguer, Past, present and future of robotic tunnel inspection, Autom. Constr. 59 (2015) 99–112. doi:10.1016/j.autcon.2015.02.003. [7] A. Jasper, Oil/Gas Pipeline Leak Inspection and Repair in Underwater Poor Visibility Conditions: Challenges and Perspectives, J. Environ. Prot. 3 (2012) 394–399. doi:10.4236/jep.2012.35049. [8] V. Upadhyay, S. Gupta and P. Agarwal, Multi-functional Remotely Operated Submersible Vehicle (ROV) System, Patent Filed with Indian Patent Ofce (2016), No. 201741022485. [9] R. Sirikonda and P. Agarwal, Underwater Lighting for a submersible ROV. Patent Filed with Indian Patent Ofce (2016), No. 201741000411. [10] V. Upadhyay and S. Gupta, A ROV System for Underwater Data Processing and Method Thereof. Patent Filed with Indian Patent Ofce (2016), No. 201741022484. [11] X. Gros, P. Strachan, D. Lowden, Fusion of Multi Probe NDT data for ROV inspection, Glob. Environ. Conf. Proceedings. Ocean. ’95 MTS/IEEE. 3 (1995) 2046–2050. doi:10.1109/OCEANS.1995.528892. [12] A. Chandra and R. Sirikonda, Underwater Cleaning Equipment for Observational Class ROVs. Patent Filed with Indian Patent Ofce (2016), No. 201641040231.
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INFRARED THERMOGRAPHY AND ITS APPLICATIONS IN REFINERY *M.Menaka and B.Venkatraman Health, Safety and Environment Group, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102. *Email: menaka@igcar.gov.in 1.0
INTRODUCTION
I
nfrared Thermography is an indispensable condition management tool for oil and gas industry being widely used for both predictive condition management as well as preventive maintenance. The method being non contact and non invasive, makes it an ideal NDE solution especially in hazardous, harsh and challenging environmental conditions that are likely in such plants. Recognizing the potential problems at an early stage will save millions of dollars and reduce non-productive down time. Thermography has proved its niche in these industries as a predictive maintenance and management tool that can recognize potential problems at a very early stage thus providing enormous monetary savings and also preventing untimely outages. The advanced infrared thermography systems with high spatial and temperature resolution, advanced focus systems, exible viewing options has created revolutionary change in the inspection by delivering ultra-high resolution images with better sensitivity as demanded by the industry from safe distances and faster inspection. Today, all the major reneries, petrochemicals and process industries use thermal imaging to ensure the safety, reliability and integrity of the components and plants in a cost effective manner. Literature survey reveals that a number of reviews have been published in the areas of condition management using thermal imaging. However, a focused article with a blend of basics, specic case studies and general factors that an investigator needs to be aware of when making such thermal surveys was found to be a gap area. This paper focuses on the application of thermal imaging especially in reneries. After a brief overview of the physical principles and factors that affect quantitative measurements, case studies pertaining to oil and gas industry including corrosion detection and thermal imaging of typical mechanical components that are invariably present in such industries are presented. 2.0 THEORY OF INFRARED THERMOGRAPHY In 1800 Sir William Herschel discovered infrared radiations. Sir William Herschel was carrying out an experiment where he was trying to measure the temperature of individual color in the light spectrum by passing the sun light through glass prism. He kept thermometers with blackened bulb on each color and measured temperature and he observed that the temperature increased from violet to red. He placed thermometer in the darkness, just beyond the red color and for his surprise the thermometer recorded temperature which was higher than red. Then he repeated the experiment and deduced the existence of radiation beyond the visible range. Though it was discovered in 1800, IR as a tool for nondestructive testing had to wait till 1950s. It was only after World War II that signicant advances in the eld of infrared
imaging and detection took place. By the late 1960s while still most of the applications were oriented towards military purposes, IR imaging started nding its niche in the eld of condition monitoring, detection of hold over res, medical diagnosis, etc. Thus, infrared imaging moved out of the laboratory into the real-life situation. In the current years, IR imaging has evolved into a mature technique [3]. The noncontact nature and exibility of the technique blended with the ingenuity of the practicing thermographer has led to extremely diverse applications such as scanning wide areas of earth from outer space, missile guidance, condition monitoring of equipment and plant components in electrical [4-6], steel [7] and process [8] industries, materials characterization, intelligent processing of materials and determination of temperature of microwave oven cooking. 2.1 PRINCIPLE OF THERMAL IMAGING Thermal imaging or Infrared imaging or thermography is the mapping of temperature proles on the surface of the object or component. It makes use of the infrared band of the electromagnetic spectrum. Infrared refers to a region of the electromagnetic spectrum between the visible and microwave. The IR spectrum extends from 0.75 mm to 1000 mm. The properties of infrared radiations are similar to other electromagnetic radiation such as light. They travel in straight lines; propagate in vacuum as well as in liquids, solids and gases. They can be optically focused and directed by mirrors and lenses. The laws of geometrical optics are valid for these also. The energy and intensity of infrared radiation emitted by an object primarily depends on its temperature and can be calculated using the analytical tools such as Wein’s law, Planck’s law and Stefan Boltzmann law. The Planck’s law describes the spectral distribution of radiation intensity from a black body and is mathematically expressed as: [Watts m-2 sr-1mm-1] -------- (1) where, Wl is the blackbody spectral radiant emittance at wavelength l (mm) c is the velocity of light (3 x 108 m/sec), h is the Planck’s constant (6.6 x 10-34 Joule-sec), k is the Boltzmann’s constant (1.4 x 10-23 Joule/K), T is the absolute temperature (K) of the blackbody. Figure 1 is the spectral radiant emittance for a black body plotted as a function of temperature.
Fig. 1 Spectral Radiant Emittance of a black body as a function of temperatures December 2017
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Differentiating Planck’s law with respect to l and setting the derivative equal to zero, we obtain the wavelength at which Wl is a maximum. The result is Wien’s displacement law, which is: mm --------- (2) where, lmax is the maximum wavelength of the radiation curve for the temperature T (K). It can be seen from eqn. 2 that as the temperature increases, the radiation peak shifts towards shorter wavelength end of the IR spectrum. Integrating Planck’s law with respect to l between the limits l = 0-¥ for constant absolute temperature T, we get the total radiant power emitted into a hemisphere from a body. This is the Stephan-Boltzmann law and is mathematically represented as: Total emmittance= (W/cm2) --------- (3) where, s = Stephan-Boltzmann constant 5.6686 x 10-12 Wcm-2 K-4. The law states that the total radiant power is proportional to the fourth power of the source temperature. Using this formula, it is possible to calculate the power radiated by the human body. For example, a body with a temperature of 300 K and an external surface area of (say) 2 m2 will radiate power of about 1 kilowatt. 3.0 INFRARED IMAGING SYSTEM A typical IR imaging system essentially consists of the infrared camera, control unit, image acquisition and analysis unit as shown in Figure 2. The heart of the system is the IR scanner. The IR scanner unit converts the electromagnetic thermal energy radiated from an object into electronic video signals. These signals are amplied and transmitted to a display monitor via an inter-connecting cable. IR imaging systems can be classied as qualitative or quantitative systems. A qualitative system displays only an isothermal map. This isothermal map needs to be corrected for emissivity variations, system non-linearity or atmospheric effects (in case of large distances). Thermal measurements are not possible from the image, as it does not indicate the temperature. In a quantitative system, the IR signal is temperature calibrated using an internal black body reference. Appropriate correction factors are also applied such that the IR image displayed has a temperature distribution approaching the true surface temperature distribution on the object.
Factors which affect outdoor thermography inspections are winds peed, solar loading and weather conditions. (a) Emissivity - Thermal measurements are inuenced by a variety of factors; emissivity is one such parameter, which has a major inuence on the temperature measurement. Emissivity is dened as the ratio of the total energy radiated by a given object surface at a particular temperature of object to the total energy that would be radiated by the surface of a blackbody at the same temperature. eo =
Total emittance from the material surface -------------------------------------------------------------------Total emittance from the surface of a black body at the same temperature ..................(5)
Black bodies have an emissivity of 1.0 while for all other bodies, the emissivity varies from 0-1. Emissivity is a function of the surface condition of the object, wavelength of radiation, viewing angle and object temperature. For opaque objects, Kirchoffs law relates the emissivity eo of the object surface to the reectivity ro. For an incident isotropic radiation, ro= 1 - eo
.................(6)
Thus objects with low emissivity, such as highly polished metal surfaces, will have high reectivity and vice versa. To give an example, the emissivity of human skin is 0.94 or 0.95 but the emissivity of a polished metal band of a wristwatch on a person’s arm is very low. When viewed using an infrared camera, the wrist watch band will appear to be at a very much different temperature (in fact higher than hand) even though it is obvious that the metal band would be at approximately the same temperature as the surface of the skin. This is clearly shown in g.3. Fig. 3. Thermal image of hand with wrist watch band. Note that the wrist watch band has a different temperature compared to hand due to emissivity variations.
For accurate temperature measurements emissivity is thus very crucial parameters. Emissivity of materials can vary from 0.01 to 0.99. Typical emissivity values of commonly used materials are given in Table 1.
Fig. 2 IR Imaging System
The main advantages of thermal imaging are that it is a noncontact method, on-line monitoring, and fast inspection rates are possible and we have a wide variety of applications. However, interpretation of thermal images requires skill and adequate knowledge of infrared physics. The main disadvantage of thermal imaging is that it is basically a surface phenomenon. Thus thick objects or defects deep inside are likely to be missed. The basic factors affecting the thermal measurement include (a) emissivity, (b) surroundings, and (c) atmosphere. December 2017
Table – 1 Emissivity values for typical materials
(b) Surroundings - It is important to have the object surroundings free from thermal radiation sources; otherwise the radiation from these sources would also be reected by the object under examination leading to erroneous values. 1
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(c) Atmosphere - The effects of atmosphere are of importance when the object is far away. The atmosphere not only attenuates the -radiation from the target but also alters the spectral characteristics. However, these effects are negligible in cases where the object under investigation is located quite close and the atmosphere is uncontaminated with vapours, smoke, fog, hot gases etc. Occasionally, one may need to make some critical measurements on an object in presence of hot air/gases as in the case of furnaces. In such cases, suitable lters such as high temperature gas lter are used along with the appropriate correction factors to take into account the ambient temperature and attenuation by these lters. In case where the objects are situated at a large distance as in the case of airborne thermography, atmospheric absorption plays a very important role. The atmospheric absorption is quite a complex process and in these cases, mathematical modelling is resorted to for estimating the temperatures. (d) Solar Reections - Solar Reections are one of the major problem when thermal imaging is done outdoors during day time. The reections of sun’s rays on the electrical components results in spurious hotspots. The effect or false indications, which can sometimes mask the true hot spots. To avoid the solar reections, thermal imaging is carried out in the night or late evening or early morning (two hours after the sunset or sunrise). Another way of reducing the effect of solar reections is through the use of appropriate lters. Figure 10 shows the spurious hot spots on one the interruptor in a nuclear power station switch yard due to solar reections encountered by the authors during a campaign. Varying the angle of observation did not eliminate the problem, which was ultimately overcome by the application of a lter. Another interesting case encountered was during the examination of 230kV transformer bushing top. Figure 11 shows the thermal images of bushing top and connector region of all the three phases of a 230kV transformer. Hot spots can be observed on all the 3 bushing tops and connectors. However repeat thermal scans from different angles revealed that these hot spots were spurious and primarily due to solar reections.
Figure 4 : Showing the spurious hot spots (indicated using arrow heads) on the interrupter due to solar reections.
(e) Wind Speed - Wind is another important parameter which can inuence our thermal measurements and cause errors in assessing the severity of the electrical fault. Wind causes convection which can mask the true temperature values of the components. Inspection of outdoor electrical installation components should be avoided when wind speed is greater than 16 km/hr (10 miles/hr). (f) Weather Conditions Humidity is one of the main factors that can result in erroneous temperature values. Figure 5 shows the infrared spectral transmittance of .
atmosphere. It can be observed that CO2 & H2O vapours are the major elements that attenuate infrared radiations to large extent. Appropriate corrections are needed for relative humidity, especially when it has to be done over long distance.
Fig. 5. Atmospheric transmittance of infrared radiations for a 6000 ft horizontal path at sea level containing 17 mm of precipitable water .
4.0 TECHNIQUES IN IR IMAGING [9] IR imaging basically exploits the non – equilibrium thermal state within a material for the detection of defects. This non equilibrium state can be achieved through the use of sources which can heat or cool the body. Such sources can be located within the material itself or can be external to it. Thus, two approaches or techniques are generally recognised in thermal NDE – (a) active and (b) passive. 4.1 Passive Approach: Passive technique involves applications where the material already contains its own internal source of heat. In many industrial processes, temperature is an essential parameter to assess proper operation and passive thermography aims at such a measurement. Important applications of the passive approach are in production, predictive maintenance, medicine, forest re detection, building thermal efciency survey programs, road trafc monitoring, agriculture and medicine. In all of these applications, abnormal temperature proles indicate a potential problem that must be addressed. For some applications, knowledge of the work-piece fabrication and operation combined with proper thermal modelling opens the door to quantitative extraction of information such as for instance the remaining thickness of refractories, etc. The typical case studies of condition monitoring application based on the passive approach undertaken by the authors are detailed below. 4.2 Active Approach: Contrary to the passive approach, the active approach, involves the application of a external thermal perturbation (heating or cooling) to the object as a whole or of a small area of interest within the object. While both heating and cooling can be applied, it is heating which is generally preferred. This can be attributed to the fact that it is easier to heat a body and a wide variety of heating sources are also available. The choice of the heating method is quite critical as this would decide the thermal contrast and hence the defect detectability. Further the application of the heat by the source itself should be non-destructive. That is it should not cause any physical or chemical damage to the object being inspected. Depending on the external stimulus, different approaches of active thermography have been developed, such as pulse thermography (PT), step heating (SH), lock in thermography (LT), vibrothermography (VT). December 2017
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The authors have used step heating using a combination of halogen lamps, as well as pulsed heating using hot air guns with provisions to vary the temperature. Both reection and transmission methods have been used for observations. The choice of the observation method adopted was based on the nature of the thermal source, its strength, object conguration, material of the object, location of the defect and its size. This article highlights the passive thermography application in oil and gas industry. 5.0
Normally all these electrical equipments are energized to about 40 % electrical load and subjected to thermal surveys.
Figure 6: Thermal image of separator vessel clearly revealing the oil, water and sand deposit in the vessel [10]
APPLICATIONS IN OIL AND GAS INDUSTRY
5.1 OFF SHORE INSPECTION Infrared thermography is a widely accepted predictive maintenance technology within land-based facilities. However, very little is published about its applications to marine systems specically offshore wherein also we have electrical and mechanical systems. In addition to cost effectiveness and increasing uptime, thermography can also ensures the safety and reliability of marine facilities wherein system failure could lead to losses and sometimes disastrous environmental effects. The primary purpose of offshore structures is to retrieve the oil and gas from deep below the ground. In the offshore environment this usually means drilling wells and maintaining and managing them via an offshore platform. An offshore platform or colloquially referred to as oil rig can be of xed or oating type. In either case, its main function is to retrieve the gas and oil from the wells. This is done through a combination of mechanical and electrical systems. Materials coming up from the wells are a complex mixture of solid, liquid and gas. Sand is one of the main and important constituent which comes along with the retrieved oil and gas from wells. These sands are cause of concern as erosion problems evolve in pipes and vessels. An effective means of monitoring sand being carried up from the wells is by conducting a thermographic survey of the separator vessels. The main function of an offshore separator is to quickly separate sand, water, oil, and gas. It is well known that these four materials have different densities, thermal capacitances and thermal conductivities. Thus based on thermal capacitances and conductivities and coupled with rm understanding of uid dynamics, thermodynamics, and erosion mechanisms, thermal imaging has been successfully employed to locate and highlight the relative levels of solids and uids (gure 6) and also the quantitative erosions that occur in the vessels due to the sand and other solids. Thermal imaging also helps in visualizing the sand’s ow pattern through the outlet nozzles, which can help to determine which valves will be more affected by the erosive power of sand [10]. Once the oil and gas are separated, these are transported. The crude oil is generally piped via undersea pipelines to large holding tanks for further rening. Thermal imaging is widely used for liquid level inspection of these tanks. The rigs in offshore are energized through a variety of electrical including distribution equipments such as SCR’s, transformers, engine generators, MP/DW motor’s etc. Identifying the extreme thermal stresses and also the various electrical issues before any of these can become major causes for outage is primarily accomplished by thermography. December 2017
5.2 GAS LEAK DETECTION Gas leak detection in pipes, vessels and various facilities of oil and gas industry is an essential and challenging task as leak detection of volatile organic compounds (VOCs), sulfur hexauoride, and lately carbon monoxide need to be detected as they are dangerous emissions. Recent developments in Infrared camera make qualitative application of gas detection possible. This detection is based on the basic principles of absorption, emission and scattering properties of infrared radiation by gas molecules due to their rotational and vibrational excitations [11] in the infrared spectral range which in turn change infrared radiation detected from the object of interest passing through gases. In recent years oil and gas industry have started to use thermal imaging extensively as preventative maintenance solutions for spotting gas leaks in tanks, pipelines and facilities to improve safety, productivity and prot. The biggest advantage of rapidly scanning large areas and miles of piping with considerable reduction in inspection time using highly specialized infrared camera nds its application in oil and gas industry.
Figure 7. LPG compressor ange dark line reveals the leak [14]
For gas leak detection, stirling cooled photonic detector based IR cameras coupled with spectral wavelength ltering to visualize the infrared absorption of gases such as methane (CH4) , hydrocarbons & VOCs, sulfur hexauoride (SF6), carbon dioxide (CO2), and refrigerants. Wavelength range preferred for detection of different gas leaks are tabulated in the table 2. The success of detection of gas leak depends on environmental conditions. If the contrast of gas leak is greater with the background then it is easier for the camera to visualize the gas leak and pinpoint its source. A Laser based backscattering technique is suggested for active optical gas imaging which works on principle of reective surface in the background. Rain and strong winds will affect eh measurement. Rain can make detection very difcult, but wind helps in visualizing the gas because it makes the gas move. Gas leak detection by these infrared cameras is qualitative and not quantitative but some cameras claim to measure mass leak rates (g/h) or volumetric leak rates (cc/ min or L/min) for most hydrocarbons. Biggest advantage of using infrared camera for detection of gas leak in oil and gas industries is operating from a safe distance.
Gases
Wavelength Range
Refrigerants
8.0 – 8.6 µm
Sulfur hexauoride (SF6) and ammonia (NH3)
10.3 – 10.7 µm
Methane (CH4), other hydrocarbons and VOCs
3.2 – 3.4 µm
Carbon dioxide (CO2)
4.0 – 4.4 µm
Carbon monoxide (CO)
4.52 – 4.67 µm
boiler has to be carried out with appropriate heat shield to protect the infrared camera from extremely high operating temperatures.
Figure 8. Typical Thermal Image of tubes inside the furnace
Figure 9. Typical thermal image of blockage in a tube
Table 2 reveals the spectral wavelength range for various gases
The ames in the furnace also have to be maintained in optimum range. Operation of the tubes at temperatures higher than the limiting temperature for a sustained period of time results in loss of ductility, cracking and creep damage leading to premature and catastrophic failure. In case the tubes are operated at lower than their optimum temperatures, it would result in lower yield. Thus, periodic monitoring of the temperature distribution of the tubes at regular intervals is necessary to ensure optimum yield of the product, smooth and safe functioning of the plant and longer life for the tubes. Blockage in the ow of uid inside the tube due to deposition of foreign materials leads to serious problems such as burst of the tube and unscheduled shutdown. This blockage overheats the tube and heat starts to concentrate on a particular area. Early detection of the hotspots can be done with the help of Thermography. Process Heaters are very similar to boilers except that tubes contain a petroleum product, which is highly ammable. If the tube gets overheated the result can be catastrophic damage. Thus on-line monitoring of tubes has to be done using Thermography [8]. The temperature variation would provide the presence of liquid levels in storage tanks. Storage tank sludge can be identied before tank cleaning. The temperature of material inside the storage tank can be studied. Local heating and hotspots can be noted with accuracy to pinpoint the location. In the petrochemical industry, this technique nds application in determination of state of insulation lining in boilers and furnaces (g. 1.4), detection of boiler casing leaks, identication of location and extent of blockages in renery process components such as in feed drums, furnace tubes (for cake deposits) and boiler tubes (insufcient cleaning and desalting) [12, 13]. It has also been used for the inspection of catalytic cracking vessels, monitoring of stack temperatures, maintenance of plant equipment such as reaction towers, detection of corrosion in oil tank shell and measurement of oil levels [14, 15].Insulation of the furnace needs to be regularly monitored to minimize heat loss through the wall. For industrial high temperature furnace applications, thermal camera with high temperature range of -40 deg C to 2000 deg C is required with very good thermal resolution of few mK. The thermal resolution of few mK is possible is achieved with semiconductor detector and stirling cooling system. Temperature mapping of the tubes inside the furnace or boiler has to be carried out with appropriate heat shield to
Figure 10. Typical hot spot observed due to improper repair of refractory lining of a furnace in a petrochemical plant [17]
Figure 11. Thermal image of wall of the furnace revealing refractory loss
Thermal measurements of tubes inside a furnace or boiler are inuenced by a variety of factors. In the present case, as can be observed from g. 2, the radiation reaching the scanner is the sum total of the IR radiations emitted by the tubes, the hot gases surrounding the tubes and the radiation reected from other surrounding sources on to the scanner. Mathematically, this can be written as Scam =to . eo. Sobj + to (1 - eo ) Satm + (1 - eo ) Sobj ...... (6) (From the tubes)
Due to hot gases surrounding the tubes
(IR reected by object)
where, Scam is the IR radiation received from all sources by the infrared imager, to is the transmission coefcient of the atmosphere between the scanner and object in the spectral window of interest, eo is the object emissivity, Sobj is the radiation received from the object and Satm is the radiation due to atmospheric self emission.
Fig. 12. IR radiation received from various sources by the thermal imager
This equation gives us the basic idea of parameters which inuence the temperature measurement of the tubes inside the furnace or boilers. Apart from furnaces, some of the petrochemical plants may also have cryogenic processes such as CO2, ammonia, and liqueed natural gas. Thermal imaging has been widely used for inspection of cold pie lines and equipment for insulation-related problems and also monitor energy and efciency losses. 5.4 CORROSION UNDER INSULATION In general corrosion continues to be a major issue for all chemical, renery and petrochemical industries throughout the world. December 2017
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Over many years, all these industries have experienced extensive damage due to corrosion. Statistics indicate that over the past 20 years corrosion [17] related failures have cost all these industries millions of dollars in plant downtime repair and replacement costs. As a result, several of these industries have been investing on corrosion monitoring and inspection program. In this article monitoring of corrosion under insulation has been discussed as it is more challenging than external corrosion monitoring. As the pipe surface is not normally accessible, detecting CUI may require the removal of the insulation and cladding. Corrosion under inspection [18] is a form of localized corrosion that may occur between the insulation and the external surface of a thermally insulated pipeline or vessel. Insulation materials such as thermal insulation, foam rubber, polyurethane, calcium silicate, and berglass used for insulation have higher adsorption properties of water, oxygen and leachable chlorides which initiates and accelerate the corrosion process. Corrosion under insulation is caused by the moisture ingress and trapping of moisture in the insulation system. Corrosion under insulation can cause considerable damage to the integrity of an insulated pipeline or vessel and if goes undetected the damage can be causing leaks to possible catastrophic events. Various methods adopted for inspection of corrosion under the insulation include visual inspection, radiography, thermal imaging, moisture detectors, and moisture removal methods (eg. drain plug). Thermographic inspections using infrared cameras helps in detection of localization of corrosion under insulation and determining the condition of thermal and cold insulation systems without taking the plant out of operation. This avoids unplanned shutdown time and unnecessary investments in maintenance. Pipelines can be scanned from a distance, which avoids time-consuming construction of scaffolding works. Fundamental principle behind the thermographic inspection is wet insulation retain heat longer than dry insulation. Regions where insulation is wet will be hotter than locations with dry insulation. Figure 13 Thermal image of the pipeline clearly revealing the corrosion under insulation (CourtesyThermovision http://thermalvision.ie/ cui-classication-withthermography) Figure 13 Thermal image of the pipeline clearly revealing the corrosion under insulation[18]
The important point to be remembered when corrosion under insulation inspection is carried out using an infrared camera is the time at which thermography survey is carried out in a day. Usually thermography to be inspected for corrosion under insulation would have seen considerable amount of solar loading. Solar heating would enhance the contrast and in turn help in detection of wet survey is carried out 2 to 3 hours after the sunset so that all the structures or all pipelines which need insulations. Hence it is obvious that thermography survey need to be carried out on a sunny day with no or minimum strong winds to avoid convection factor. Thermal camera with thermal detector (un-cooled micro bolometer detector) December 2017
and spectral wavelength ranging from 7 microns to 14 microns is highly recommended. Temperature range of camera may be 40deg C to 500 deg C with thermal resolution of 0.04 deg C. 5.5 ELECTRICAL AND MECHANICAL SYSTEMS [19] All the industries have electrical and mechanical systems to operate the plant for various purposes. Monitoring of the electrical and mechanical systems in all these industries is vital for smooth operation of the plants. Thermographic inspection is recommended for condition monitoring of electrical and mechanical systems as they quickly pinpoint problems, reduce downtime and equipment damage prevents catastrophic failures and avoids costly shutdowns. In electrical and mechanical systems, excessive heat generation by the system is an excellent indicator of upcoming trouble. Electrical systems typically suffer from problems such as loose connections; dirty contact surfaces, broken strands of wire, cracked insulators, load imbalances and corrosion. These problems increase the resistance to the current ow, which in turn results in excessive resistive heating. The rate of generation of heat (H) in the component or circuit is proportional to the square of the current (I) passing through it. Mathematically, H a I2 R t ----------(7) Where, R is the resistance and t is the time. If left undetected, this heat buildup can result in meltdown of connection breaking the circuit and causing sudden blackouts. In some cases, this can also be a potential re hazard. Infrared inspection of electrical power distributions systems can be performed right from the point where electricity is produced i.e. in generating stations till it reaches the consumer.
Figure 14. Thermal image of Figure 15. Oil storage tank electrical installation with high above the transformer clearly temperatures mapped at the L indicating the level of oil pad circuit breaker
Mechanical Systems: IR imaging is an indispensable part of periodic condition monitoring programs in the industries mentioned above. Apart from these, IR is also applied for the inspection of mechanical systems and condition monitoring of rotating equipments in these industries. Electrical motors, pumps etc frequently fail due to excessive vibrations, poor lubrication, misalignment of bearings and shaft, deteriorating insulations, poor windings, etc. All these cause an increase in temperature which can be easily detected by IR imaging.
Figure 16 shows the typical thermal image of motor and pulley
6.0 CONCLUSION Thermography is a versatile tool for condition monitoring with wide application range. The non-contact and on line monitoring of the defects adds great potential to the technique for condition monitoring in a wide range of industries and for wide variety of components. Many of the thermographic applications carried out within the oil and gas industry are highly challenging. Accurate evaluation and reliable interpretation requires a good appreciation of the processes, equipments and analytical understanding of the fundamentals of heat transfer physics in order to properly identify and diagnose problems and conditions. The recent advances in IR sensor technologies with possibilities of remote transmission / wireless capabilities and coupled with analysis using Articial Neural Networks and data fusion offers many distinct possibilities especially as an "IOT" based technology for predictive condition as well as structural health management tool in these industries. REFERENCES: [1] G.A. Raine and N. Smith, Back to Basics: NDT of On and Offshore Oil and Gas Installations Using the Alternating Current Field Measurement (ACFM) Technique, Materials Evaluation., Vol. 54, No. 4, April 1996, pp. 461–462, 464–465 [2] B Mc Queen Smith, "Condition Monitoring by Thermography",NDT International,June 1978, pp. 121 – 122 [3] Maldague. X.V.P.,Non Destructive Evaluation of materials by Infrared Thermography", Springer Verlag Publications, 1993. [4] B. Venkataraman, S. Kanmani, C. Babu Rao ,Baldev Raj and T. Prem Kumar "Thermographic Investigation of 230 kV Main Transformer of MAPS – I " IGCAR Report No. IGC/DPEND/R&D/92/03. (1992) [5] B. Venkataraman and Baldev Raj, Inservice Inspection at Tarapur Atomic Power Station, - Thermographic Campaign, 1992, IGCAR Report : IGC/DPEND/R&D/92/04, Part "B". [6] B. Venkatraman, S. Kanmani, C, Babu Rao, D.K. Bhattacharya and Baldev Raj, Inservice Inspection of Electrical Components at Nuclear Power Stations by Infrared Thermographic Imaging, Proceedings of
Non-Destructive Evaluation and Quality Assurance (NDE-92), Ed. By C.R.L. Murthy, Baldev Raj, O. Prabhakar and A. Srinivasulu, Published by Interline Publishers, Bangalore, 1992, pp. 102-109. [7] L M Rogers, "Applications of Thermography in the Steel Industry", Steel Times Annual Review, 1978, pp. 661 – 673 [8] Paul Grover, "Infrared inspection of Boilers and Process Heaters", MaterialEvaluation, October 1991, pp1272-1274. [9] Xavier P V Maldague and Patrick Moore, "Infrared and Thermal Testing", ASNT Non Destructive Testing Hand Book, Vol. 3, 2001 [10] Sonny James,Common Thermography Uses and Applications within the Petrochemical, Offshore Oil and Gas, Chemical, and Power Generation Industries www.irinfo.org,2009 [11] J. F. Tegstam and R. Danjoux, Gas leak detection in the oil and gas industry using infrared optical imaging , Thermography Colloquium 2007, DGZFP, Germany http://www.ndt.net/article/dgzfp-irt2007/Inhalt/v03.pdf [12] Michael Vollmer and Klaus-Peter M¨ollmann, Infrared Thermal Imaging, WILEY- Publisher, ISBN: 978-3-527-40717-0, 2010. [13] Hui, S. U. N. "Application of Infrared Thermal Imagery Technology in Catalyzed Lining Failure Diagnosis [J]." Industrial Furnace 6 (2011): 011. [14] Sims, D. Using infrared imaging on production tanks and vessels. Inframation 2001, Proceedings vol. 2, pp. 119–125 [15] Sims, D. Monitoring the processconditions in oil eld production vessels with infrared technology. Inframation 2004, Proceedings vol. 5, pp.273–280 [16] B.Venkataraman, S. Kanmani, C. Babu Rao, D.K. Bhattacharya & Baldev Raj,"Thermographic Investigation At Tamil Nadu Petro Product, Manali Madras", IGCAR Report No.: IGC/DPEND/R & D/92/11. [17] Qiang, Shi, Zhu Wensheng, and Ge Yongtao Hu Yang. "Application of Infrared Thermo Imagery in Petroleum Reneries."Corrosion & Protection in Petrochemical Industry 1 (2013): 020. [18] Henderson, Steven. Inspection technology addresses corrosion under insulation. Hart„s E & P. 2010; 83(8):41-2. [19] B.Venkatraman, M.Menaka, P.Kalyanasundram and Baldev Raj, Infrared Imaging-an Overview on its Multifarious Possibilities and applications in IGCAR, Journal of Non- Destructive Testing & Evaluation Vol.5, Issue 2 September 2006. pp 54-67
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BLACK AND RED WATER BASED PASTE FOR MPI TESTING Amongst our presently used MPI Consumables Black/ Red colored (147A, 146C) Magnetic Powders are in a high demand. The reason being that the suspension medium is water and secondly the indications formed give a very good contrast. However, the products are available as liquid concentrates in bottles. In order to overcome the above referred shortfalls, FerroChem have now developed Red and Black colored, water suspendible Magnetic Powders in ‘PASTE’ form, product No.146C/J-6 & 147C/J-6 respectively. FEATURES · The products are available in plastic containers as 500 gms. · The quantity required for preparing a bath is 15 gms per ltr. One can of 500 gms can be used for preparing 33 ltrs of water bath. · Economically priced
Easy handling of magnetic paste, as no need of mixing or shaking at the time of making bath · Many transporters refuse transportation of liquids where as the paste is acceptable by all transport facility ·
FERROCHEM NDT SYSTEMS PVT. LTD www.ferrochemndtsystems.com
LOCK-IN THERMOGRAPHY IN THERMAL STRESS ANALYSIS (TSA) We offer full range of magnetic yokes like permanent magnets, AC/DC, Battery Operated etc. All these yokes are designed to meet the highest standards (ASTM E1444) & operating conditions in the field. All these yokes are portable, light weight & water resistant. FEATURES · DC filed Intensity potentiometer · Articulated legs with span of 300mm · Can be used for AC demagnetization · Input single phase 110-250 VAC 50/60 Hz · No risk of sparking or “hot spots” on the job
RADICAL SCIENTIFIC EQUIPMENTS PVT. LTD. www.radicalscientific.com December 2017
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ULTRASONIC THICKNESS GAUGES We offer Ultrasonic Thickness Gauges manufactured by M/s. JMD NDT Inc., USA for almost all applications. From affordable Steel Thickness Gauge (STG) to the most advanced Corrosion Thickness Gauge (CTG-DL & CTG-DL+) & Precision Thickness Gauge (PTG-DL & PTG-DL+) on the market. ·
STG: This is a simple thickness Gauge with 3 probe options viz. 5MHz probe for normal applications, 2.25MHz probe for castings and 7.5MHz with 4.75mm diameter probe for small diameter pipe applications.
·
CTG-DL: This is the advanced model with datalogger facility, through coat, B-Scan and High Temperature Probe option with a working range upto 500 degrees. CTG-DL+: This model is equipped with A-Scan facility.
·
PTG-DL: This is mainly for Precision applications providing very high resolution of 0.001mm.
·
PTG-DL+: This model is equipped with A-Scan facility.
NDTS INDIA (P) LIMITED www.ndts.co.in
MAGNETIC YOKE We offer full range of magnetic yokes like permanent magnets, AC/DC, Battery Operated etc. All these yokes are designed to meet the highest standards (ASTM E1444) & operating conditions in the field. All these yokes are portable, light weight & water resistant. FEATURES · · · · ·
DC filed Intensity potentiometer Articulated legs with span of 300mm Can be used for AC demagnetization Input single phase 110-250 VAC 50/60 Hz No risk of sparking or “hot spots” on the job
ARORA TECHNOLOGIES (P) LIMITED www.arorandt.com
eeciflux
Magnetic Flux Yokes Permanent Magnets PY-1
PY-2
EF-2Y/EF-3Y
EF-6Y
AC/DC Yoke
AC Yoke
EF-4Y/EF-5Y EF-1Y Battery Powered DC Yoke
the best in ndt
AC Yoke
110/220v
8, 2nd Floor, Jyoti Wire House, Near Kolsite, Off Veera Desai Road, Andheri (W),Mumbai 400 053. India Tel No.: +91-22-6150 3800 / 26 / 40 ♦ Fax:- +91-22-6691 9792 Email: ndtsales@eecindia.com ♦ Web: www.eecindia.com Regional Offices: CHENNAI, BANGALORE, KOLKATA, HYDERABAD, PUNE, PATNA, NAGPUR, NEW DELHI, VADODARA
December 2017
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INTERNALTIONAL EVENTS CALENDAR 2018 APRIL 2018 10-12: Aerospace Event. Organised by the British Institute of Non-Destructive Testing. Venue: BAWA Conference Centre, Bristol, UK. Contact: Conference Services, BINDT, Midsummer House, Riverside Way, Bedford Road, Northampton NN1 5NX, UK. Tel: +44 (0)1604 438300; Fax: +44 (0)1604 438301; Email: conf@bindt.org; Web: www.bindt.org MAY 2018 7-9: Annual Conference of the German Society for NDT (DGZFP Jahrestagung 2018). Venue: Leipzig, Germany. Contact: Steffi Dehlau, German Society for Nondestructive Testing (DGZfP), Max-Planck-Straße 6, 12489 Berlin, Germany. Tel: +49 30 67807 120; Fax: +49 30 67807 129 Email: tagungen@dgzfp.de; Web: www.dgzfp.de 15-17: MFPT 2018: Intelligent Technologies for Equipment and Human Performance Monitoring. Venue: Sheraton Virginia Beach Oceanfront Hotel, Virginia Beach, USA. Contact: MFPT, 715 Twining Road, Suite 135, Dresher PA 19025, USA. Email: amy@mfpt.org; Web: www.mfpt.org 27-1 Jun: 12th International Fatigue Congress. Covering all aspects of fatigue. Venue: Poitiers, France. Contact: SF2M, 28 rue Saint Dominique, 75007 Paris, France. Tel: +33 (0)1 46 33 08 00 Email: fatigue2018@sf2m.fr; Web: www.fatigue2018.com JUNE 2018 11-15: 12th European Conference on Non-Destructive Testing (12th ECNDT). Venue: Swedish Exhibition and Congress Centre, Gothenburg Contact: Sweden MEETX AB, 412 94 Gothenburg, Sweden. Tel: +46 31 708 86 90; Fax: +46 31 20 91 03 Email: ecndt2018@meetx.se; Web: www.ecndt2018.com 24-29: 14th Quantitative Infrared Thermography Conference (QIRT 2018). Venue: Berlin. Contact: Steffi Dehlau, German Society for Nondestructive Testing (DGZfP), Max-Planck-Straße 6, 12489 Berlin, Germany. Tel: +49 30 67807 120; Fax: +49 30 67807 129; Email: tagungen@dgzfp.de; Web: www.qirt2018.de
December 2017
26-28: Digital Imaging and Ultrasonics for NDT 2018. Venue: Foxwoods Resort, Mashantucket, Connecticut, USA. Contact: ASNT, 1711 Arlingate Lane, PO Box 28518, Columbus, OH 43228-0518, USA. Tel: +1 614 274 6003; Fax: +1 614 274 6899; Email: conferences@asnt.org; Web: www.asnt.org JULY 2018 10-13: 9th European Workshop on Structural Health Monitoring (EWSHM 2018). Venue: Manchester, UK. Contact: Conference Services, BINDT, Midsummer House, Riverside Way, Bedford Road, Northampton NN1 5NX, UK. Tel: +44 (0)1604 438300; Fax: +44 (0)1604 438301 Email: ewshm2018@bindt.org; Web: www.ewshm2018.com OCTOBER 2018 28-31: ASNT Annual Conference 2018. Venue: George R Brown Convention Center, Houston, Texas, USA. Contact: ASNT, 1711 Arlingate Lane, PO Box 28518, Columbus, OH 43228-0518, USA. Tel: +1 614 274 6003; Fax: +1 614 274 6899; Email: conferences@asnt.org; Web: www.asnt.org
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15TH APCNDT - A REPORT 13th To 17th November, 2017
T
he Asia Pacific Conference for Non-Destructive Testing & Prof Tsuyoshi Mihara - Department Head of Material Science (APCNDT) considered a major regional event for the Asia and Engineering Tohoku University. Pacific Federation for Non-Destructive Testing (APFNDT) and its member societies, was held from 13th to 17th November An MOU was signed between Mr. D. & Prof Tsuyoshi Mihara 2017 at Marina Bay Sands, Singapore. Department Head of Material Science and Engineering Tohoku University.J.Varde-President, ISNT & Mr. , SINDT. The conference included technical and scientific program and workshops, which presented the latest developments in the field of research and development as well as the applications of NDT in all major industrial areas. 250 technical contributions were accepted from practicing NDT professionals, engineers, scientists and developers in academia and industr y (manufacturers and end-users) covering all aspects of nondestructive testing including novel applications, research and technology development across all industrial areas. The exhibition organised in conjunction with the conference emphasized the close link between research and development and the equipment and instruments used in the industry. Key Note speakers for the event were Dr Mike Farley Chairman of the ICNDT (2008-2016), Dr B. Venkatraman - Director of IGCAR Health, Safety and Environment Group, Prof Krishnan Balasubramaniam -Dean of Indian Institute of Technology Madras, Dr Younho Cho - Professor of School of Mechanical Engineering Pusan National University, Dr Gong Tian Shen President of The Chinese Society for Non Destructive Testing (ChsNDT), Dr B. Stephen Wong - Professor of School of Mechanical and Aerospace Engineering Nanyang Technological University, Prof Len Gelman - Professor of Vibro-Acoustic Monitoring, School of Aerospace, Transport and Manufacturing
ISNT President & SINDT signing the MOU
Dignitories at APCNDT event
ISNT President & SINDT signing the MOU December 2017
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FIRST NDT SEMINAR - A REPORT 28th & 29th January, 1979 Organised by : Hindustan Aeronautics Ltd, Bangalore. Compiled by Shri. P. Vijayaraghavan, HAL Bangalore
T
he First Seminar on Non Destructive Testing was Ÿ Proceedings of the seminar containing 24 full length papers was bought out. organized by NDT Centre, Central laboratory, Hindustan Aeronautics Limited, Bangalore, on 28th and 29th Ÿ The delegate fees was Rs 50/- only !!!
January 1979. Convenors of the seminar were Dr. Krishnadas Nair & B. Chatterji. Ÿ
Key note address were given by Dr. S. Ramaseshan, Deputy Director National Aeronautical Laboratory; Jawaharlal Nehru Fellow, Raman Research Institute Bangalore .
Ÿ
A souvenir was released containing 24 abstracts and there were 24 advertisers
Ÿ
32 papers were presented in 7 sessions
Ÿ
Exhibition of NDT equipments, products and technical literature was organized on both the days
Ÿ
50 registered delegates participated, including exhibitors
Mr. P.D. Chopra MD, HAL, Bangalore, addressing the gathering. Sitting from L to R : Mr. B.Chatterji, Dr. S. Ramaseshan, Dr. Krishnadas Nair
December 2017
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NATIONAL GOVERNING COUNCIL MEMBER'S LIST (NGC) 1. Shri D.J. Varde President, ISNT M: 9821131522 president@isnt.org.in 2. Shri Rajul R. Parikh Hon Secretary M: 9820192953 secretary@isnt.org.in 3. Shri R.J. Pardikar President Elect, ISNT M: 9442613146 r.j.pardikar@gmail.com 4. Dr. B. Venkatraman Vice President – ISNT M: 9443638974 qadbvr@gmail.com 5. Diwakar Joshi Vice President, ISNT M: 9689928561 diwakarj@gmail.com 6. Shri Samir K. Choksi Hon. Jt. Secretary - ISNT M: 9821011113 choksiindia@yaqhoo.co.in 7. Shri P. Mohan Hon. Jt. Secretary - ISNT M: 94901 67000 metsonic@sify.com / mohanp45@rediffmail.com 8. Shri S. Subramanian Hon. Treasurer M: 9444008685 nricsubramanian@gmail.com 9. Shri P.V. Sai Suryanarayana Hon. Jt. Treasurer M: 9490142539 sai895956@gmail.com 10. Shri. V. Pari Immediate Past President ISNT M: 9840104928 pari@scaanray.com
CHAPTER CHAIRMEN / SECRETARIES
MEMBERS 11.Shri. S. Adalarasu 12.Shri. Anil V. Jain 13.Shri. D.K.Goutham 14.Shri. Ambresh Bahl 15.Shri. Mandar Vinze 16.Shri. S.N.Moorthy 17.Shri. Mukesh Arora 18.Shri. Bhausaheb K. 19.Shri. Pangare 20.Shri. B.Prahlad 21.Shri. Sadasivan N. 22.Shri. R.Sampath 23.Dr. Sarmishtha Palit 24.Shri. B.K.Shah 25.Shri. Shashidar Pallaki 26.Shri. A.K.Sing 27.Shri. A.K.Singhi 28.Shri. R.Sundar 29.Shri. Sunil Gophan 30.Shri. Vivek Rajamani 31.Shri. N.V.Wagle 32.Shri. R.B.Bharadwaj 33.Shri. M.N.V. Viswanath 34.Shri. Bikash Ghose 35.Shri. Anilkumar Das 36.Shri. Jaiteerth Joshi 37.Shri. T.Kamaraj 38.Shri. R.G. Ganesan 39.Shri. Sreemoy Saha
PERMANENT INVITEES 40. Prof. S. Rajagopal 41. Shri G. Ramachandran
PAST PRESIDENTS 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52.
Shri V.R. Deenadayalu Shri K. Balaramamoorthy Shri Ramesh B. Parikh Shri A. Srinivasulu Shri Dr. Baldev Raj Shri S. I. Sanklecha Shri Shri D.M.Mehta Shri K. Viswanathan Shri Dilip P. Takbhate Shri K. Thambithurai Dr. P. Kalyanasundaram
53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 65. 66. 67. 68. 69. 70. 71. 72. 73. 74.
Shri D.S Kushwah Shri Rajeev Vaghmare Shri Vijayaraghavan Shri Shashidhar P. Pallaki Dr. Krishnan Balasubramaniam Shri R. Vivek Shri Dayaram Gupta Shri T. Kamaraj Shri P. Mohan Shri M. Venkata Reddy Dr. Amitava Mitra Shri Tarun Kumar Das Shri B. Anandapadmanaban Shri G. Kempulraj Shri C.K. Soman Shri V. Sathyan Shri Dipankar Gautam Shri Sreebash Chandra Saha Shri Ambresh Bahl Shri A. Varshney Shri Hemant Madhukar Shri Samir K. Choksi
75. 76. 77. 78. 79. 80. 81. 82. 83. 84. 85. 86. 87. 88.
Shri Jeevan Ghime Shri Parag W. Pathak Shri M. S. Shendkar Shri Bikash Ghose Shri V Ranganathan Shri B Karthikeyan Shri Elangovan Mudliyar Shri D B Sathe Shri Mathivanan Shri V. Deepesh Shri G. Levin Shri Shanmughavel Shri R.Venkatasubramanian Shri Kashyap N. Bhatt
EX-OFFICIO MEMBERS 89. Dr. M.T. Shyamsunder 90. Shri P.P. Nanekar 91. Shri S. Viswanathan 92. Shri T. Loganathan 93. Dr. Baldev Raj 94. Shri V. Pari 95. Dr. P. Kalyanasundaram
NATIONAL CERTIFICATION BOARD MEMBER'S LIST (NCB) 1. 2. 3. 4. 5.
Dr. M.T. Shyamsunder Shri P.P. Nanekar Shri T. Loganathan Shri S. Viswanathan Shri B. K. Shah
REGIONAL CONTROLLER OF EXAMS 6. Shri S.K. Bandyopadhyay 7. Shri S.R. Ravindran 8. Shri Jayaprakash Hiremath 9. Shri K. Balaramamoorthy 10. Shri R.B. Bhardwaj 11. Shri V. Manoharan 12. Shri Avinash U. Sonuwane 13. Shri R. Sundar 14. Shri Phani Babu 15. Shri Dilip Gatti 16. Shri ME. K.A Nerurkar
17. Shri Bikash Ghose 18. Shri Chintamani Khade 19. Shri G.V.S. Hemantha Rao EX-OFFICIO MEMBERS 20. 21. 22. 23. 24. 25.
Shri D.J. Varde Shri. Rajul R. Parikh Shri S. Subramanian Dr. B. Venkatraman Shri Diwakar D. Joshi Dr. Baldev Raj
CHAPTER REPRESENTATION 27. Shri Hemant Madhukar 28. Dr. Krishnan Balasubramaniam 29. Shri M. S. Shendkar 30. Shri P. Mohan
December 2017
61
ISNT LEVEL III COURSES SN
Method
Course Duration
Exam Date
Course fees Including 18% GST (INR)
1
Ultrasonic Testing
02/04/2018 to 06/04/2018
08/04/2018
18,880 (16,000+2,880)
Specic – Weld
Do
Specic– Cast/ Wrought 2
Basic
3
Radiographic Testing
4
Specic– Cast/ Wrought
Do
2950 (2500+450)
Magnetic Particle Testing
23/04/2018 to 25/04/2018
Liquid Penetrant Testing
** Visual Testing
11,800 (10,000+1,800)
01/05/2018
13/05/2018
4720 (4000+720)
2950 (2500+450) 18,880 (16,000+2,880)
4720 (4000+720)
Specic – Tubes
Do
2950 (2500+450)
Specic – Rods / Wire
Do
2950 (2500+450)
** Leak Testing
14/05/2018 to 18/05/2018
19/05/2017
2950 (2500+450)
2950 (2500+450)
Do 07/05/2018 to 11/05/2018
2950 (2500+450)
2950 (2500+450) 18,880 (16,000+2,880)
Do
Specic– Cast/ Wrought
4720 (4000+720) 2950 (2500+450)
Do 06/05/2018
2950 (2500+450)
2950 (2500+450) 11,800 (10,000+1,800)
Do
02/05/2018 to 05/05/2018
4720 (4000+720)
2950 (2500+450)
2950 (2500+450)
Do 28/04/2018 to 30/04/2018
Specic – Weld
** Eddy Current Testing
27/04/2018 Do
Specic– Cast/ Wrought
8
4720 (4000+720) 2950 (2500+450)
Specic – Weld
7
4720 (4000+720)
Do
Specic– Cast/ Wrought
6
22/04/2018
2950 (2500+450) 18,880 (16,000+2,880) 18,880 (16,000+2,880)
Specic – Weld
Specic – Weld
5
15/04/2018
4720 (4000+720)
Practical Exam Fees (If applicable) Including 18% GST (INR) 2950 (2500+450)
2950 (2500+450)
Do 09/04/2018 to 13/04/2018 16/04/2018 to 20/04/2018
Exam Fees Including 18% GST (INR)
21,240 (18,000+3,240)
4720 (4000+720)
Specic – Weld
Do
2950 (2500+450)
Specic– Cast/ Wrought
Do
2950 (2500+450)
2950 (2500+450)
2950 (2500+450)
ASNT LEVEL III COURSES Total in INR
Course Duration
Dates
Ultrasonic Testing - UT
5 days
2nd to 5th April 2018
16,000
2,880
18,880
Basic
5 days
9th to 13th April 2018
16,000
2,880
18,880
Radiographic Testing
5 days
16th to 20th April 2018
16,000
2,880
18,880
Magnetic Particle Testing - MT
3 days
23rd to 25th April 2018
10,000
1,800
11,800
Liquid Penetrant Testing - PT
3 days
28th to 30th April 2018
10,000
1,800
11,800
Visual Testing
4 days
2nd to 5th May 2018
16,000
2,880
18,880
Eddy Current
5 days
7th to 11th May 2018
16,000
2,880
18,880
Leak Testing - LT*
5 days
14th to 18th May 2018
18,000
3,240
21,240
Method
Course Fees in INR
Tax @ 18% in INR
December 2017
62
We hope that this section on NDE Patents will be found interesting and continue to trigger your curiosity on this very important topic of Intellectual property. Please send your feedback, comments and suggestions on this section to mandayam.shyamsunder@gmail.com United States Patent 9,557,302 Ultrasound inspection system and ultrasonic quality control method Inventors: De Miguel Giraldo Carlos, Lambert Gildas, Martinez Oscar, Elvira Luis, Romero David, Gomez Ullate Luis, Montero Francisco Assignee: Airbus Operations S.L. (Getafe, ES) An ultrasound inspection roller provided with a wheel, a sensing system and a support for holding the sensing system inside the wheel, a wedge connected to the ultrasound sensing system at one end and provided with a curved prole at its other end facing the wheel, adapted to the curvilinear shape of the wheel, and a liquid of a density higher than 9.9*10.sup.2 kg/m.sup.m3 placed inside the wheel such that the sensory system, the wheel and the wedge are acoustically coupled. The roller allows the early detection of problems during manufacturing of composites and the performance of corrective measures in real time, and assures a good coupling between the transducers and the material to be inspected in dry conditions.
United States Patent 9,759,690 Method and system for nondestructive ultrasound testing Inventors: Hoctor Ralph Thomas, Zingelewicz Stephen Eric Assignee: General Electric Company (Niskayuna, NY) Methods, systems and computer program products for nondestructive ultrasound imaging are provided. An example method denes a plurality of subarrays, each comprising a plurality of ultrasound transducer elements. The method transmits a plurality of ultrasound beams from each of the plurality of subarrays, each ultrasound beam being transmitted at a preset beamsteering angle. Subsequent to each transmit, the method receives, at the array, a plurality of ultrasound reections corresponding to the plurality of ultrasound beams. For each point to be imaged, the method selects one set of received element data for each of the plurality of subarrays. The selected set of element data corresponds to an ultrasound beam having a focal point closest to the point to be imaged. Finally, the method reconstructs a point to be imaged based on the selected received element data, and constructs an ultrasound image by repeating this process for each point to be imaged.
United States Patent 9,803,976 Methods and apparatus for measurement or monitoring of wall thicknesses in the walls of pipes or similar structures Inventors: Simonetti Francesco, Instanes Geir Assignee: Clamp On AS (Bergen, NO) A method and an apparatus for guided-wave tomographic measurement or monitoring of wall thicknesses of the walls of pipes and similar structures are disclosed. The method is characterized in that use is made of transducers preferably positioned in at least two groups of a plurality of transducers arranged in a spaced apart pattern on the external surface of the structures, the transducers individually transmit ultrasound signal into the pipe wall in that each ultrasound signal propagates within the pipe wall from the transmitting transducer and is received at one or several receiving transducers, and the received ultrasound signal is converted to an electrical signal by the receiving transducers and recorded by the transceiver. Measurements are performed by using a further plurality of transducers that are placed apart from the two groups of a plurality of transducers. There is also disclosed a method for guided-wave tomographic measurement or monitoring of wall thicknesses in the walls of pipes and similar structures producing a set of measurement data by using the apparatus.
United States Patent 8,670,952 Non-destructive inspection instrument employing multiple sensor technologies in an integral enclosure Inventors: Drummy Michael Assignee: Olympus NDT Inc. (Waltham, MA) A non-destructive inspection (NDI) instrument includes a sensor connection system congured to receive test signals from at least two different types of NDI sensors which are congured to obtain test signals from an object being tested. The sensor connection system has sensor-specic connection circuits and at least one common sensor connection circuit. A data acquisition circuitry is coupled to the sensor connection and has sensor-specic data acquisition circuits and at least one common data acquisition circuit. It is further coupled to a common digital data processor which executes sensor-specic processing modules and at least one common processing module. A common display screen and user interface is coupled to the data processor and enables programs including sensor-specic user interface modules and at least one common user interface module. The sensor types preferably include all of or any combination of an ultrasound sensor, an eddy current sensor and acoustic sensor.
United States Patent 9,804,128 Turbine blade testing device and testing method thereof Inventors: Yamamoto Setsu, Miura Takahiro, Semboshi Jun, Ochiai Makoto, Murakami Masato, Nomura Hiroshi , Fuchi Takuya Assignee: Kabushiki Kaisha Toshiba (Minato-ku, JP) According to one embodiment, a testing device of a turbine blade includes: a non-compressive elastic medium brought into close contact with a platform of the turbine blade in a state fastened to a turbine rotor; a probe which has piezoelectric elements arranged in an array and transmits ultrasound waves toward a fastening portion of the turbine blade through the elastic medium and receives echo waves; and a display portion for imaging an internal region of the fastening portion on the basis of the echo waves and displaying the same.
December 2017
United States Patent 9,390,520 Method and system of signal representation for NDT/NDI devices Inventors: Bourgelas Tommy Assignee: OLYMPUS SCIENTIFIC SOLUTIONS AMERICAS INC. (Waltham, MA) Disclosed is a method and system to provide an improved signal representation of non-destructive test/inspection instruments by proper color display, in order to emulate as closely as possible, the visual rendering effect of those seen in the traditional non-electronic testing, including penetrant testing and magnetic particle testing. The foregoing object of the invention is preferably realized by providing an eddy current or phased array instrument with a color palette module that allows the deployment of an array of color representation system typically used in traditional non-electronic testing methods.
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Word Search Puzzle MAGNETIC PARTICLE TESTING The “Word Search Puzzle”, contains more than thirty (30) words related to Magnetic Particle Testing. These include techniques, terminologies, phenomenon, famous people, etc. These words are hidden in the puzzle and may be present horizontally, vertically, diagonally in a forward or reverse manner but always in a straight line. Find them and have fun !! Please send your answers to mandayam.shyamsunder@gmail.com
Magnetic Particle Testing Equipments
eeciflux
EF 6Y Yoke
Black light LED
Coil
EF 4Y Yoke
Mobile Unit
Bench Unit
PY-1 Yoke
8, 2nd Floor, Jyoti Wire House, Near Kolsite, Off Veera Desai Road, Andheri (W),Mumbai 400 053. India Tel No.: +91-22-6150 3800 / 26 / 40 ♦ Fax:- +91-22-6691 9792 Email: ndtsales@eecindia.com ♦ Web: www.eecindia.com Regional Offices: CHENNAI, BANGALORE, KOLKATA, HYDERABAD, PUNE, PATNA, NAGPUR, NEW DELHI, VADODARA
September 2017 Acoustics & Ultrasonics Puzzle Solution
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S C B A N D W T R A E S O D A M P I N G A N S O U R C E
S H A D O W A S V P E W E D G E F C R P A U T R R O A U N T R A N S M I T T T E N S I T I V I T N U A T T E R I N G T I D T H O N S D U C E R O A Q U S U P T I L E R A R T N E T O F D R
S W H E E E S O T R O P Y T Z C H O
I N T E R F A C E R Y
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December 2017
RADICAL