SA Mechanical Engineer Aug 2012 by Promech Publishing

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

AN ENGINEER’S VIEW

Chris Reay

Chairman of the Working Committee: Communications (SA Institution of Mechanical Engineering)

Crucial Importance of the Mining Industry Most commentaries on the status of the mining industry in South Africa refer to the decline in our rankings within the international comparisons. Mining is essentially the industry that developed the South African economy and which spawned the support industries that provided the equipment and services.

ur unique Government Certificate of Competency evolved from the early 1900s to develop safer working conditions and improved skills for the activities of the mining industry. A recent international survey ranked South Africa at the top of the list for the value of minerals in the ground at the awesome figure of R2,5 trillion, well ahead of Russia in second place. With such credentials we have, however, declined in our competitiveness as growth markets have increased the demand for resources. We effectively lost out on participating in the last resources boom that witnessed countries such as Australia, Canada, many in Africa north of us and many in South America actively rise in the provider stakes. Various reasons have been given for this, but the most frequently identified are poor and slow policy making, the references to nationalisation, the reduction in our capacity for research and development and the accompanied loss of experienced skills. In more recent times, the sudden increase in energy costs and industrial strike action have added to the reversal in our competitiveness.

Estimates put the human resources running the Australian mining industry to be over 50% of South African origin In September the next Electra Mining exhibition will be held which is one of the largest of its type internationally and which, from all accounts, will be well supported. In particular the action in Africa north of us is significant and we have seen many of our project management, design and construction skills moving to manage these northern projects. Some of our EPCM companies have such projects make up the bulk of their order book. Further afield, estimates put the human resources running the Australian mining industry to be over 50% of South African origin.

placed a number of mines on a caretaker basis or a scramble to try and manage with fewer contracted resources, can the stakeholders: investors, government, and the mining industry address the skills issues that, even in the present circumstances, is in short supply? Most people I talk to express the fear about what we are going to do when the lights really come on again - once the European and American recessionary conditions change and the world demand for minerals resumes?

‘Boer maak a plan

Reports on the diminished R&D capacity and skills in the research establishments, that in the 80s and early 90s were world leaders in mining research and development, are of great concern as the ability to innovate disappears. Clearly mining activity also depends on reliable infrastructure and good logistics which are not well positioned either at present. In the vein of ‘n boer maak a plan’, can we tackle this huge challenge? It cannot be beyond our ability and willingness to do some serious mining skills development together with that needed across the whole engineering domain. We really need to curtail our incessant, negative outlook on this state of affairs and try to get collective, positive group action to turn our mining status around. Perhaps the Electra Mining event could energise some reality here. The SAIMechE is to facilitate the first of its Soap Box sessions which will be interesting to watch. Let’s hope the speakers will be able to address some of these issues and spawn some industry enthusiasm to make things happen. One can safely say that the survival of South Africa depends on it.

With the slump in the platinum price which has THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

August 2012 VOLUME 62 NUMBER 8

Contents

On the cover: Hansen Transmissions SA Tel: (011) 397-2495 www.hansen.co.za

Cover Story

Pumps, Pipes & Valves

8 Building a Future 11 Prominent Professionals

35 Hose Pumps Firmly Established 37 Pipe, Laying, The Right Way

Computers in Engineering

Opinion

13 Balanced Approach 15 The Future is Closer Than Ever

39 Soapbox

Machine Tools

40 On the Par

17 Machines Enable Progress

POWER GENERATION TODAY Copyright

All rights reserved. No editorial matter published in “SA Mechanical Engineer” may be reproduced in any form or language without written permission of the publishers. While every effort is made to ensure accurate reproduction, the editor, authors, publishers and their employees or agents shall not be responsible or in any way liable for any errors, omissions or inaccuracies in the publication, whether arising from negligence or otherwise or for any consequences arising therefrom. The inclusion or exclusion of any product does not mean that the publisher or editorial board advocates or rejects its use either generally or in any particular field or fields.

21 The White Stuff 26 Power Generation News

Power Transmission 29 Factors Affecting Gear Bearings

Education

Regulars

3 An Engineer’s View 6 Institution News 37 SAIT 41 Market Forum

The monthly circulation is 4 242

Produced by: PROMECH PUBLISHING, P O Box 373, Pinegowrie, 2123, Republic of South Africa Tel: (011) 781-1401, Fax: (011) 781-1403 Email: samecheng@promech.co.za, www.promech.co.za Managing Editor Susan Custers Editor Kowie Hamman Circulation Catherine Macdiva Advertising Mark Bennett DTP Zinobia Docrat / Donovan Vadivalu Subscriptions Please email us at accounts@promech.co.za if you wish to subscribe to “SA Mechanical Engineer” at R405,00 (excl postage and VAT) per year; R1 020,00 per year for Africa/Overseas. Disclaimer

PROMECH Publishing and The South African Institution of Mechanical Engineering as well as any other body do not take responsibility for the opinions expressed by individuals.

Printed by: Typo Colour Printing, Tel: (011) 402-3468/9 FSC (Forestry Stewardship Accreditation)

Official Publication of THE SA INSTITUTION OF MECHANICAL ENGINEERING and endorsed by:

 CORROSION INSTITUTE OF SA  SA PUMP MANUFACTURERS ASSOCIATION  SA VALVE AND ACTUATORS MANUFACTURERS ASSOCIATION  THE SA INSTITUTE OF TRIBOLOGY  NUCLEAR INSTITUTE  SA INSTITUTE FOR NON-DESTRUCTIVE TESTING  NATIONAL SOCIETY OF BLACK ENGINEERS  INSTITUTE FOR CERTIFICATED MECHANICAL AND ELECTRICAL ENGINEERS  SOUTH AFRICAN ASSOCIATION OF CONSULTING ENGINEERS  ASSOCIATION OF SOCIETIES FOR OCCUPATIONAL SAFETY AND HEALTH  THE SOUTHERN AFRICAN ASSOCIATION FOR ENERGY EFFICIENCY (SAEE)

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

THE SA INSTITUTION OF MECHANICAL ENGINEERING

Council 2011/2012 Office Bearers

President .................................................. G Barbic (George) Vice President .............................................. D Findeis (Dirk) National Treasurer ............................... KK Nyangoni (Kudzai)

SAIMechE’s EXHIBITORS SOAPBOX SESSIONS AT ELECTRA MINING 10 – 14 September 2012

Branch Chairpersons

Central ...................................................... M Cramer (Mike) Eastern Cape ................................................ W Rall (William) KwaZulu/Natal ................................................. J Moto (John) Mpumalanga Highveld.............................. L Odendaal (Louis) Western Cape ........................................... Dr D Blaine (Debbie)

Portfolios:

Communications/Strategic Planning/ Specialist Group..................................................CD Reay (Chris) Young Engineers Forum................Prof B Collier-Reed (Brandon)Education: Universities of Technology............... E Zawilska (Ewa) Membership .................................................... E Zawilska (Ewa) Professional Development Programme..........M Black (Malcolm) Technology Programme ................................. SZ Hrabar (Steve) To be confirmed....................................................A Roos (Andre) To be confirmed.........................................G Bartholomew (Bart)

Be sure to visit Electra Mining, the world’s second largest mining exhibition, and gain free attendance to the Exhibitors Soapbox sessions organised by SAIMechE in the MAN Building, Expo Conference Centre, Nasrec. 30 minute corporate presentations on products, services, technologies and trends will be given throughout each day of the exhibition. This first time ever Electra Mining Exhibition feature is designed to give the discerning user/purchaser the opportunity to make informed decisions. A programme of the sessions will be published in due course. Final opportunity to get your product and services message across to discerning users and purchasers! Exhibitors wishing to purchase soapbox sessions may contact SAIMechE’s Carey Evans, National Events Admiistrator at Tel. 031 764 7136 & carey@saimeche.org.za. Carey Evans - carey@saimeche.org.za

Chief Executive Officer: Vaughan Rimbault National Office Manager: Anisa Nanabhay PO Box 511, Bruma, 2026 Tel: (011) 615-5660, Fax: (011) 388-5356 Email: info@saimeche.org.za Website: www.saimeche.org.za Membership: Central, Eastern Cape, Mpumalanga & KZN: membership@saimeche.org.za Membership: Western Cape: saimeche.wc@vodamail.co.za

Company Affiliates Alstom Power Service SA Babcock Africa Limited Bateman Engineered Technologies Bosch Projects Fluor SA GEA Air-cooled Systems Hansen Transmissions SA Hatch Africa Howden Power Howden Projects Industrial Water Cooling MBE Minerals (SA) (Pty) Ltd (previously KHD Humboldt Wedag SA) Megchem Eng & Drafting Services

Mod-U-Flow Osborn Engineered Products SA Rotek Engineering RSD a division of DCD-Dorbyl S.A.M.E Water Sasol Technologies SEW Eurodrive Siemens SNC-Lavalin SA Spicer Axle SA Spirax Sarco SA Technical Systems Thyssenkrupp Engineering Transvaal Pressed Nuts & Bolts Ultra-Flow Engineering Services Vital Engineering Weir Minerals Africa Winder Controls

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

THE SA INSTITUTION OF MECHANICAL ENGINEERING

Forthcoming Training Events Programmes, fees and registration forms may be obtained from Carey Evans on E-mail carey@saimeche. org.za or Tel. 031-764-7136. Also, detailed individual event programmes are available from Carey. Code

Abbreviated Title

Date – Start

Date – End

Region

C0212

Boiler House; Safety Valves

5 Sep 12

7 Sep 12

Cape Town

C2512

Effective Management Roles

26 Sep 12

Cape Town

E0212

Boiler House; Safety Valves

3 Oct 12

5 Oct 12

East Rand

A0212

Boiler House; Safety Valves

10 Oct 12

12 Oct 12

Durban

E2912

Lubrication & Lubricants

17 Oct 12

East Rand

E61A2

Leadership & Management Roles

17 Oct 12

18 Oct 12

East Rand

E2912

Lubrication & Lubricants

17 Oct 12

East Rand

C5612

Problem Solving for Engineers

24 Oct 12

Cape Town

E5612

Problem Solving for Engineers

14 Nov 12

East Rand

A5612

Problem Solving for Engineers

21-Nov-12

Durban

In-House Workshops To obtain a comprehensive list of workshops that may be held In-House or to discuss your corporate training needs, kindly contact National Events Manager, Linda Robinson on E-mail linda@saimeche.org.za or Tel: 031 764 7136.

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

COVER STORY

Building a Future Multi-national companies based in South Africa have to comply with certain BEE criteria in order to participate in official government projects such as the Kusile and Medupi power stations currently being built, the infrastructure upgrades underway and various mining projects on the go.

t first sight, it may appear that there are no real direct Fritz Fourie, managing director of Hansen Transmissions SA benefits for those who do make an effort to follow the industrial gearbox manufacturer, Hansen Transcompliance route, however for those companies who missions SA based in Jetpark near Johannesburg. are in the country for the long haul, they undoubt- “Getting actively involved in an educational project edly assist in creating a sustainable future for the is far removed from our daily business of building country as a whole. gearboxes, but it has been an eye-opener to a real world right here on our doorstep,” he says. “Every Far removed from our daily business of building day you hear about the shortcomings of education gearboxes, but it has been an eye-opener to a real world in this country, but you only realise the extent of it right here on our doorstep once you become involved.”

Education

This view is shared with “SA Mechanical Engineer” by Fritz Fourie, managing director of international

Because multi-national companies often can’t sell shares in the company for BEE purposes due to company policy, there are other options open for international companies to achieve an acceptable rating in order to do business with the government. “In order to attain the required level four BEE classification, not only for current contracts, but also for future projects, we chose to go the equity equivalent route in terms of the share requirement,” explains Fritz. “This necessitated that we invest 25% of the net value of the company in a sustainable DTI-approved project aimed at rural development, job creation or education and training.

Digital media

“Over the past two years we, therefore, established the Ulwazi Express Trust and have just launched our first project which is part of an ongoing educational programme aimed specifically at previously disadvantaged schools in rural areas,” elaborates Fritz. “In

“The launch of the system at a school in the north-western province

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

COVER STORY

this drive, our company has partnered with QAE (Quintessential Africa Edutainment) who manages the day-to-day activities of bringing digital visual media to television sets in classrooms in rural areas across the country.” Unlike public educational TV where schools have to have TV reception and can only view programmes at prescribed times, the Ulwazi system does not require a TV network for broadcasting. Programmes can be ordered for viewing at any time the teacher specifies. “This system uses cellphone networks and satellite technology to broadcast a wide variety of educational programmes from the main control centre in Johannesburg,” explains Fritz. The teacher can therefore schedule a programme on a specific subject matter at a time when they’re actually dealing with the subject in class. At the time of its launch in July this year, the system has already been installed at 24 sites in the north-western province at various high schools, training centres and colleges. Fritz adds, “Although the educational content of programmes covers all subjects, there is a special focus on mathematics, sciences and life skills in order to stimulate a general interest in science and engineering among the learners.”

Sustainable funding

From the company side there is no active participation in the daily running of the project, but Fritz has nevertheless taken a personal interest in the project. “Every day you hear about the problems and shortcomings of the South African educational system, but only when you take a personal interest and get out there to see the conditions, do you realise just how serious it actually is,” says Fritz.

The teacher can schedule a programme on a specific subject matter at a time when they’re actually dealing with the subject in class

There is a special focus on mathematics, sciences and life skills in order to stimulate a general interest in science and engineering among the learners training artisans, making bursaries available to our staff’s children and where we’re supporting local small business suppliers from whom we source a large percentage of components for our range of services and products.” Fritz Fourie, Hansen Transmissions SA Tel: (011) 397-2495, Email: ffourie@hig-shi.com

“Although all the official departments and organisations involved with education have given us their full support, this type of project requires sustained funding over the long term due to the daily running costs of broadcasting far and wide. To this end we’ve committed to making around R8.6 million available to the trust over the next seven years.

Better basics

“In terms of BEE it is often a difficult decision to pick the right type of project, but we’re satisfied that choosing education has been the right one because ultimately the engineering industry and the country as a whole, will benefit from better basic education,” Fritz remarks in conclusion. “This is something we are already seeing as a result of our other BEE initiatives where the company is

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

MONTHLY COLUMN

Prominent Professionals Adrie Conradie:

became my responsibility, not only to manage the assembly of the trucks which arrived in bits and pieces, but also to manage and build the complete 200 tonne capacity dump bodies locally at the mine to a specific design supplied by the OEM.

Group Manager Engineering, Exxaro

Academic School

Langenhoven High School, Riversdale

Any awards

Graduate studies

Both my final year project and the Ph.D. project were awarded best project at the University of Stellenbosch. One which stands out is when we have achieved one million hours of fatalty free shifts at the Tshikondeni coal mine (2005), a mine recognised as one of the most challenging underground mines in the world.

University of Stellenbosch: Bachelors degree in Mechanical Engineering, cum laude;

Post-graduate

University of Stellenbosch: Masters degree, cum laude; Ph.D. Mechanical Engineering. Pretoria University: Certificate in Maintenance Practice; Masters in Engineering Management, cum laude.

Future – a concept, a dream or a wish

Adrie Conradie

Professional Bodies

Professional Engineer, ECSA; Government Competence Certificates for Mines & Works and Factories; Full member of South African Colliery Engineering Association.

Career Path

A main aspiration is to unify engineering through cross-functional integration and collaboration between the different business functions and processes in an engineering organisation like ours. Secondly, we should all strive to think and design and operate more ‘green’ in earnest.

Projects

First employer

As a mechanical engineer at Iscor Research and Development in Pretoria.

Growth path

Iscor from 1995 for about six years as mechanical engineer in research, then planning & development engineer, manager diagnostics engineering, senior maintenance engineer. Then Kumba Resources for five years as assistant resident engineer, chief and resident engineer on various operations. In 2006 became mine manager at Exxaro’s Tshikondeni mine, then program manager for Coal at Exxaro business growth department (head office) until my current position.

Present employer and position

Group Manager, Engineering at Exxaro responsible for multidisciplinary engineering: mechanical electrical, civil and industrial engineering.

Most challenging

My Ph.D. project. It was a combination of complex maths and engineering. It was all about the optimisation of large engineering systems with specific reference to dry cooling systems.

Most rewarding

The Komatsu 730 dump truck project.

Commentary Are there shortcomings in the Mechanical Engineering Industry in South Africa?

Mechanical engineering has been a stand-alone discipline on its own for too long where we’re all working in silos. Secondly, I’d like to see much more attention given to maintenance engineering.

How would you mend this?

We have to optimise the interaction between the different engineering disciplines.

Achievements A project

Just after starting on Grootegeluk mine in the late nineties the mine bought a fleet of Komatsu 730 dump trucks. It

Message to young engineers

Ask questions, don’t be afraid to ask! As important as this is, so is it to listen.

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

COMPUTERS IN ENGINEERING

Balanced Approach Asset-intensive industries such as chemicals, mining and food processing are characterised by sizeable capital investments in machinery and equipment. Companies in these industries will also typically have a large maintenance budget. IT systems, the computerised maintenance systems generally cannot provide relevant information to help the business make informed planned maintenance decisions. The information that is required is a combination of cost, replacement value, historic reliability, and process criticality (if equipment should fail how could this impact production, and what is the probability of failure?).

Complex calculation

Clearly, this is a complex calculation, requiring not only a large amount of data, but a high level of data integrity and statistical analysis. Most importantly though, maintenance data without information regarding the actual role of the equipment in the production process is next to useless – yet most maintenance systems are implemented independently of production teams.

Gavin Halse MD, ApplyIT

aintenance is often the largest fixed cost (other than raw materials) in such companies. In a medium-sized chemicals plant, the annual maintenance budget could be 10% of the original capital investment. This ratio of annual maintenance cost to capital investment can vary significantly by industry and depend on many factors, such as plant age, the level of complexity and the amount of moving machinery, but in almost all cases maintenance costs are substantial and need to be carefully managed.

Businesses might be tempted to reschedule planned maintenance into the future But what about profits?

As with all businesses, manufacturing companies have to make sustainable profits. During periods when production demands are high, businesses might be tempted to reschedule planned maintenance into the future. Other factors that lead to maintenance being delayed could include cost pressures in the company or, in the case of very old plants, a decision could be made to minimise maintenance as the plant has reached end of life. In practice, when management ask questions regarding planned or scheduled maintenance, they are often flying blind. Despite significant investment in

Many plants use their CMMS (computerised maintenance management system) as a tool for improving the efficiency of the maintenance processes. The emphasis is on reducing “wrench time”. “Wrench time” is described as the proportion of time during which craftsmen are being kept from productively working on a job site by delays such as waiting for assignment, permits, parts, tools, instructions, travel, coordination with other crafts or waiting for equipment information. A well-implemented CMMS achieves all these benefits by (for example) ensuring spares are available in the store, making available standard procedures and instructions for defined tasks, and providing equipment information and accurate maintenance history. Furthermore, a CMMS can help plan maintenance work accurately and reliably, generating job cards or work orders automatically. But is this enough?

In isolation

The problem with most CMMS implementations is that the system is focused on optimising maintenance in isolation. Other factors, such as the opportunity cost of breakdowns and lost production, are not taken into account. So for example, a "minor" piece of equipment such as a steam valve might have the potential to bring down the entire plant should it fail. Shutting down and starting up a process plant can be an expensive exercise – failures of this type should clearly not be a frequent occurrence. Yet the standard CMMS information such as spares cost, part numbers, maintenance costs and historical failures may not reveal the true role of this particular steam valve in keeping the plant running.

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

COMPUTERS IN ENGINEERING

The industry has developed concepts such as OEE (overall equipment effectiveness) to help place equipment performance in the context of the business. This is a measure of availability (downtime), performance efficiency (reduced capacity) and quality (rework, scrap). However, several analysts have pointed out fundamental flaws with OEE as a measure of maintenance effectiveness. For example, “performance efficiency” could be as much a result of good performance of the production department as of the maintenance department.

Conflicting objectives

Separating key performance indicators (KPIs) of these different, often conflicting objectives, requires careful design of the systems and a comprehensive understanding of the underlying process and business. CMMS systems that are implemented as standalone “islands” are not effective. Nor are so-called “integrated” CMMS systems of much use if the integration is purely with financial and procurement systems, as these systems are also usually segregated from the realities of dayto-day production processes. Effective CMMS systems therefore need to relate production information with maintenance and equipment information.

Management often flying blind Modern IT technologies make this possible through combining process information (from control systems, for example) with maintenance data, and combining all of this with contextual information from production technicians and artisans.

More than just filing

A recommended best practice when implementing a CMMS system is to start by going back to basics and regard it as a strategic project with major business implication. The project needs involvement from the finance, production, maintenance and safety departments. All too often we see the CMMS system as simply an advanced electronic filing system belonging to the plant engineer. If this is the case in your business, then you may need to consider a re-implementation. Gavin Halse, ApplyIT: (031) 275 8080, halseg@applyit.co.za

Errata

We apologise for printing the incorrect caption on pg28 of the June issue where we incorrectly named Pamela Pindela as the parnter of Johnstone Chikwanda of Sasol. Pamela is a colleague and the Logistics Export Manager at Sasol.

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

COMPUTERS IN ENGINEERING

The Future Is Closer Than Ever Plantwide Optimisation has many facets and means different things to different parts of an organisation. Put simply, its primary objective is to get all parts of a manufacturing environment working to maximise asset utilisation, productivity and uptime and seamlessly integrate this with all other aspects of the organisation. It is not just a one-step process either; it requires constant management and monitoring to help move towards continuous improvement across the enterprise, throughout the plant lifecycle.

lantwide optimisation covers more than just managing technological assets. At the enterprise level, many other internal and external elements have to be factored in. If they are not, the plant cannot claim to be truly optimised.

Footholds

Track and trace and serialisation are all gaining significant footholds in industries outside their more traditional pharmaceutical markets, as customers demand more transparency and industry bodies enforce tighter regulation. Many suppliers also face demands from the companies they supply with regards to the use of standards, such as S88, and commonality of communication protocols for the machines they supply. Another hot topic is sustainability, as organisations worldwide strive to not only reduce their energy consumption, but also to manage the energy they use effectively in order to minimise their environmental footprint. Energy costs can be addressed in simple applications by using variable-speed drive technology or intelligent motor control systems. In more complex applications, it can be evolved through advanced power management programmes that predict, assess and audit usage, and then create plans and procedures to help optimise energy use.

Single network approach

These enterprise level issues can only be successfully addressed if the right information is available

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

COMPUTERS IN ENGINEERING

to the right people at the right time. “Thanks to data visibility, scalability and interoperability – across a common Ethernet network – we can help companies achieve a richer, information enabled enterprise. Marc Baret, director of marketing, Rockwell Automation – Europe, Middle-East and Africa, says “By connecting and combining discrete automation devices and system data with that from process control systems and ERP systems, seamless information flow becomes achievable. Once this data is available, it can be used in the most effective manner”.

Sharing of data, from high-level programmes all the way down to simple on/off signals, is made incredibly simple

Many formats

Arguably the most important element of any plantwide optimisation programme is the ‘backbone’ that acts not only as the conduit for the data, but also for all the automation and safety functions of the machines and processes. With multiple networks, protocols and suppliers, bottlenecks are inevitable, as data is transposed from one format to another, adding unwanted complexity and delays to any process. Through the use of a single network, in this case a standard, unmodified Ethernet Industrial Protocol network (Ethernet/IP), Rockwell Automation is revolutionising the seamless transfer of data from point to point; from the simplest component-level I/O block, all the way up to the overarching company MES system.

Intrinsic value

With Ethernet/IP providing the link between discrete control, process, safety, automation and motion, investment in training, software licences, machine design, programming, parts management and data handling can be significantly reduced. Why reinvent the wheel? With the single network approach utilising a proven automation platform, Integrated Architecture, the sharing of data, from high-level programmes all the way down to simple on/off signals, is made incredibly simple. Another important area to consider is safety. Mark concludes, “Safety should be considered as an intrinsic, value-adding part of an installation, both in terms of cost and performance, and not as a costly addition, as is often the case.” Jeff Sandison, Tel: (011) 654-9700 Fax: (011) 654-9706 Email: jksandison@ra.rockwell.com

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

MACHINE TOOLS

Machines Enable Progress Modern machines tools can be seen as enablers with the ability to give manufacturers a considerable edge over traditional techniques.

t the forefront of supplying advanced machine tools is Retecon, a company with a long and illustrious history in this country. Its success is built on supplying local companies with machine tools from the world’s top-ranked suppliers across all manufacturing industries. In the metal working, fabrication and steel processing industries these include top-flight names like Trumpf laser-cutting, punching and forming machines, DMG/Mori Seiki lathes, mills and machining centres, Studer cylindrical grinders as well as Ficep, the leading Italian company for processing of angle iron, flat sheets as well as drilling and sawing lines for beams and profiles.

Stay abreast of modern machine tool’s capabilities in order to be able to design for the future Future is bright

The Ficep CNC machine range is increasingly being used for the pre-manufacture of power pylons to meet burgeoning demand for power distribution from Eskom’s new build projects, as well as that of Independent Power Producers. “In South Africa a number of manufacturing lines are using the Ficep machines to manufacture pylons to meet requirements for the soon to be completed Madupi and Kusile powerplant’s distribution networks,” says Retecon managing director, Han-Peter Neth. “The power generation industry is traditionally a major user of angle-iron fabrications for pylons, although the Ficep machines can be used for a variety of different applications, such as boom manufacture for lifting equipment, refineries and platforms, as

well as conveyor platforms and structures. “With the option of completely automating the machine processes, plants can produce high volumes of precision-made section that are ready for on-site erection wherever required. “The precise nature of the CNC controlled process ensures that contractors working on-site in often remote and inhospitable areas can simply assemble the pylons with no additional work required on site. Automation means that high volumes can be produced to meet growing demand locally and in the rest of Africa,” he adds.

Feather in the cap

Retecon recently received further confirmation of its status as the country’s leading supplier of technologically advanced machine tools with its appointment as the sole agent for DMG / Mori Seiki machine tools. This follows the announcement that world leaders in machining centre, lathe and mill technologies, Germany’s DMG and Japan’s Mori Seiki brands would form a joint venture company known as DMG/ Mori Seiki. Although the two brands were separately represented in the country, it was announced that as a result of the collaboration all Mori Seki machines would be now sold and supported through Retecon – who previously held the rights to DMG

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

MACHINE TOOLS

machines in South Africa. As a result the company also becomes responsible for the support of all Mori Seiki machines sold through the manufacturers previous agent in South Africa. Both brands have ruled the global machine tool market for decades with DMG’s forte being absolute precision machine tools and high technology manufacture, while Mori Seiki is best known for its precision high speed manufacturing machines in everything from manufacturing automotive parts

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

to aerospace. “In the past, the two brands were fierce competitors with a healthy respect for one another, now they form a formidable alliance and are set to become the dominant force in supplying advanced machines globally,” Hans-Peter enthuses.

Making the difference

He explains that the company is founded on service of the highest standards. That is why it attracts the attention and partners with top notch machine manufacturers from around the world.

August 2012

MACHINE TOOLS

“Companies represented by us - like DMG / Mori Seiki, Trumpf and Ficep - spend $-Millions on research and development to solve manufacturing dilemmas and to perfect manufacturing processes. They push the boundaries and discover new, easier, faster and better ways of doing things. “A good example is the development of laser and ultrasonic machining techniques that enable high-speed machining centres to precisely cut hard or brittle materials. Even ten years ago this would not have been possible and engineers would not have designed products with this in mind.

Globally competitive

“Even the interface with CAD/CAM programs and other technologies are aimed at making the manufacturing process simpler and faster and more accurate. “Cheap or free labour in the East is easily circumnavigated by our local manufacturers if they automate and minimise the amount of hands that touch a work piece. They can only do this if they embrace technology. Engineers should also stay

abreast of modern machine tool’s capabilities in order to be able to design for the future,” HansPeter concludes. Hans-Peter Neth, Retecon, Tel: (011) 976-8600, Email: neth@retecon.co.za, www.retecon.co.za

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

POWER GENERATION

PROMECH PUBLISHING Tel: (011) 781-1401 Fax: (011) 781-1403

The White Stuff

Email: samecheng@promech.co.za Website: www.promech.co.za Managing Editor: Susan Custers Editorial: Kowie Hamman Advertising: Mark Bennett Circulation: Catherine Macdiva DTP: Zinobia Docrat/ Donovan Vadivalu Disclaimer PROMECH Publishing does not take responsibility for the opinions expressed by individuals.

TICKER TAPE

All rights reserved. No editorial matter published in “Power Generation Today” may be reproduced in any form or language without written permission of the publishers. While every effort is made to ensure accurate reproduction, the editor, authors, publishers and their employees or agents shall not be responsible or in any way liable for any errors, omissions or inaccuracies in the publication, whether arising from negligence or otherwise or for any consequences arising therefrom. The inclusion or exclusion of any product does not mean that the publisher or editorial board advocates or rejects its use either generally or in any particular field or fields.

The verdict’s back and enviro-fashion gurus appear to be making it official: white is alright again

hite roofing has become the pet project of former president Bill Clinton, who is spearheading a move to target our overheads all over the world. He was recently quoted as saying: “Every black roof in New York should be white; every roof in Chicago should be white; every roof in Little Rock should be white. Every flat tar-surface roof anywhere! In most of these places you could recover the cost of the paint and the labour in a week.”

A R155-million demonstration undersea generation plant is to be installed off the eThekwini coast to harness the powerful Argulhas current in a test project that could lead to the development of an ocean-current energy facility that could add 5 MW and 8 MW to the national electricity grid. If the project went ahead, it would be the first in South Africa. Ford Motor Company’s new one-litre EcoBoost engine has been named the 2012 International Engine of

Skyrocketing temperatures

Supporters put up a convincing argument for the practice. Most of the roofs in the world are dark coloured and in the heat of the full sun, temperatures can skyrocket by 50oC to peak at 90oC resulting in increased energy bills, spiking electricity demands and air pollution due to heat island effects. From a more practical perspective, roofing materials deteriorate more quickly and require more frequent maintenance.

the Year. The engine - small enough to fit on an A4 sheet of paper – was designed at Ford’s technical centres in Dunton, UK and Merkenich, Germany Morocco’s state power utility ONE has selected a consortium of local Nareva and United Arab Emirates-based Kharabel FZE to develop a 300 megawatt wind farm in the Southern Tarfaya region. The consortium valued the project at R2.9bn. The wind farm would be Africa’s biggest.

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

POWER GENERATION

improvement. There are also noticeable savings in overall electricity consumption, minimising pressure on electricity supply. From a construction perspective, bulk insulation could be entirely replaced by roofing systems that both reflect solar radiation and provide emission to the sky.

300 million cars

According to Wikipedia sources, if all urban, flat roofs worldwide were whitened, the reduction in carbon emissions would be 24 Gigatonnes, or equivalent to taking 300 million cars off the road for 20 years. This is based on the fact that a 93 m2 white roof will offset 10 tons of carbon dioxide over its 20 year lifetime.

A 93 m 2 white roof will offset 10 tons of carbon dioxide over its 20 year lifetime White or reflective roofs increase only 5-14oC above ambient temperature, offering airconditioning savings of up to 30%. Roofing lifespan is significantly increased and thermal efficiency sees a marked

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

For obvious reasons, cities would be the first areas to benefit from implementing white roofing. The US-based White Roof Project is encouraging Americans to paint their roofs white since the States is such a contributor to global warming. However, the trend is spreading worldwide and even South African companies are getting in on the action. Under a programme, led by the Clinton foundation, Johannesburg is one of fifteen cities around the world to begin cutting carbon emissions by

August 2012

POWER GENERATION

renovating city-owned buildings with green technology, with the potential to reduce energy use by 20% to 50%.

Local front

Product manufacturers have also updated their ranges to incorporate relevant products. Abe Construction Chemicals’ new abeproof thermoshield is a cost-effective water-based coating that uses advanced insulation technology to reduce the interior temperature of buildings while, simultaneously, serving as a waterproofing coating. Mike Armstrong, a.b.e. strategic product manager, says the product is formulated with fine spherical particles that minimise surface temperatures on roofs and walls by re-emitting most of the heat energy before it can penetrate a building. “This lowers interior temperature and reduces energy costs for cooling the building. The product is ideal for roofs and walls in both commercial and residential buildings. It is effective even with dark colours,” he says. This echoes the information provided by other sources, many of whom say that cool roofs can even be dark, as long as the correct materials are used. While white roofs are inherently cool, a dark roof can be upgraded with the application of a reflective coating – good news for those who aren’t planning to re-roof anytime soon.

‘Journal of Climate’, claims that the project may actually exacerbate the problem Nay-sayers

Of course, as with any contentious topic there are those who disagree on the details. A study published in the ‘Journal of Climate’, claims that the project may actually exacerbate the problem, citing findings of a global climate model which analyse the relationships between various environmental conditions. These experts believe that lower local temperature means less water evaporates and rises up to eventually form clouds. The decrease in clouds allows more sunlight to reach the Earth’s surface, leading to higher temperatures overall.

Not cooling down

The model also predicts that much of the light reflected by rooftops will eventually be absorbed by dark carbon soot and particles prevalent in the air above urban areas. This could limit local cooling and cause warming elsewhere as the particles drift away. However, the study didn’t calculate how the change would impact energy use, or how such a change could impact emissions and their effect on climate. An important issue that they raise is that the real problem lies in the emission of pollutants that contribute to global warming. So whether you support the idea of white roofs or not, you should be looking at your carbon footprint. The world is not going to cool down on its own. Sources: www.wikepedia.org, www.whiteroofproject.com, www. discovermagazine.com, NYCoCoolRoof

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

POWER GENERATION NEWS

Winning Approval and turbine valves at Eskom’s Tutuka power station. The trials, which took place over eighteen months, comprised in situ testing and comparison of the performance of the Aesseal packing with that of an identical valve packed with a competitor’s product. Subsequent to official Eskom approval, the company has delivered gland packing into stock at Tutuka, to be drawn by Eskom staff as required.

Duncan Joubert of Aesseal

Exhaustive trials have led to official approval of Aesseal gland packing as a specified product for critical boiler

Duncan Joubert, Aesseal manager in charge of sales to Eskom, says that Eskom’s approval of the packing represented an important step forward for a product relatively unknown in South Africa. “It recognises that our packing has been thoroughly tested under operational conditions and over a long period of time, by the country’s biggest energy company. “Not a single failure occurred during the

First of its kind The wet flue gas desulphurisation (WFGD) system being installed at Kusile Power Station by the Cosira Group/Alstom Consortuim, is the first of its kind in South Africa. The WFGD will dramatically reduce the sulphur dioxide (SO2), content from the power plants flue gases.

reduce (SO2) from flue gas emissions, advanced proven technology such as wet flue gas desulphurisation processes are adopted to improve on the limits set by international committees,” says John da Silva, chief executive officer of the Cosira Group.

While wet flue gas desulphurisation has been a popular choice for flue gas scrubbing on the international market, South Africa has chosen, until now, to utilise other methods of decreasing sulphur dioxide from gas emission. “Although other methodologies exist to

“WFGD has been a popular choice for fossil-fuelled power stations for over 25 years in Europe and the United States. The technology is set to become a standard in developing countries as awareness of its benefits increases. There is no doubt that the WFGD is

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

test period. We expect that this will pave the way for us to introduce this packing not only to other power stations, but also to customers in other sectors with packing applications in critical valves,” Duncan concludes. Aesseal, Rob Waites, Tel: (011) 466-6500, rwaites@aesseal.co.za

the preferred environmentally ‘friendly’ choice as it removes at minimum 95% of sulphur dioxide gases from the emissions,” he adds. “Sophisticated sensors interconnected with the WFGD plant control systems continually record fuel gas emissions. These sensors provide the control systems with accurate monitoring information necessary to ensure that emissions are kept to the performance levels of the plant. Should emissions exceed the acceptable levels; alarms will trigger control mechanisms which adjust the plants’ inputs to correct the levels.” Cosira Group, John da Silva, Tel: (011) 8176600, Email: john.dasilva@cosiragroup.com Web: www.cosiragroup.com

POWER GENERATION NEWS

Local solar inverters AEG Power Solutions has made a significant investment in South Africa with the construction of a premium manufacturing facility for its utilityscale solar inverters and skytron combiner boxes for its monitoring and control solutions. The factory, based in Montague Park in Milnerton, just outside of Cape Town, is 3 400 sqm, with the capacity to produce at least 200 MW per annum. The plant will be officially inaugurated in September 2012, but has already started manufacturing the PV.500 Inverters and 1MW TKS Solar containers, with 13 employees and will ramp up to the PV.630 and PV.800 by the end of 2012. AEG Power Solutions, Claire Pairault, Email: claire.pairault@aegps.com

Calculating Carbon Footprint One of the key challenges in the carbon emissions market is to find a carbon consultancy with experience and knowledge of the local market. “In South Africa the list of experts in this field is relatively short. This is because the market is still in its early stages,” says Harmke Immink, director at Promethium Carbon, a carbon advisory firm. Harmke says that in South Africa only a handful of carbon consultants have more than five years’ experience in climate change and carbon management. “There are carbon consultants entering the market either from an environmental auditing, energy-efficiency or the sustainability business background. As a result, they need to develop on-the-job experience, as with any other profession.” The main challenge in calculating a credible carbon footprint is to do it correctly the first time. The credibility of a carbon footprint becomes even more important when the company wants to participate in projects such as the Carbon Disclosure Project or go public with the information when using it in a marketing campaign.

“A business’s reputation can be damaged if their carbon footprint is published without verifying it first, and it turns out to be wrong,” Harmke adds. Another challenge in determining a credible carbon footprint is to have access to quality data covering the direct and indirect processes within the business and the specific industry within it functions. Consultants use standards such as ISO 14064 and then custom-design a framework for each project within industry reporting guidelines. With government’s pending carbon tax on companies, calculating a credible, verified carbon footprint is essential. Third party verification and assurance of climate data is a key next step. Harmke adds that the South African national accreditation services (SANAS) is implementing a programme to provide accreditation to carbon auditors under ISO 14065. Promethuim, Harmke Immink, Tel: 0861 227 266, Fax: 086 589 3466, Email: harmke@promethium.co.za, Web: www.promethuim.co.za

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

Pumps Valves Systems

Knockout Unexpected Outages MDX pumps are designed to match the life cycle of your mills. At a major copper mine in Chile, GIW’s patented hydraulic design and advanced materials have almost tripled parts life. The result was a reduction in costs and increased production at the mine site. Got a hard rock slurry problem? GIW offers expert slurry pumping solutions around the globe. Minerals are everywhere. So is GIW. KSB Pumps and Valves (Pty) Ltd www.ksbpumps.co.za

A KSB Company

MDX 750 Pump

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

POWER TRANSMISSION

Factors Affecting Gear Bearings It has become standard practice for conveyor manufacturers to specify the bearing life required of a conveyor gear unit. In the recent past it was accepted that the bearing life of a gear unit should be 50 000 hours L10ha23. Prior to that no bearing life was specified and gear units were sized and selected purely for their mechanical and thermal capabilities. Today that is no longer the case. If a gear unit is sized and selected today, the driving factor is bearing life requirements. Many end users today specify an L10ha23 life of 100 000 hours.

ue to the emphasis being placed on bearing life, it has become extremely important that the concept of bearing life, what it means, the limitations and exceptions, be fully explored and understood. The purpose of this paper is to display how the concept of L10h bearing life can be understood within the realm of practical and realistic operating conditions.

converted to an equivalent load. This equivalent load is equal to the constant stationary radial load which applied to the same bearing with a rotating inner ring and stationary outer ring, would yield the same life as the actual combination of loads.

Bearing life rating

Where P is the Equivalent Dynamic Load [N]

Conventionally, bearings are rated in terms of L10life. L10 life is that life which 90% of a group of bearings operating at a given set of conditions will complete or exceed. Failure of bearings, in terms of L10 life, is defined as the first occurrence of fatigue on one of the rolling elements or on one of the raceways. This fatigue is usually in the form of spalling. The L10 life concept is based on extensive experimental data. It has also been found that the median life or life that 50% of a group of bearings will achieve is five times that of the L10 life. The term ’rating life’ and ’life’ of a bearing has been standardised as the L10 life by organisations such as American National Standards Institute (ANSI) and the International Standards Organisation, hereafter referred to by its acronym ISO. The dynamic load ratings and rating life of roller bearings are standardised in the ISO standard ISO 281: Roller bearings – Dynamic Load Ratings and Rating Life. It is important to note that the L10 life concept is relevant only to fatigue of the rolling elements and raceways. It must be stated, and stated clearly, that failures due to causes such as wear, excessive heat generation and retainer failure are not covered by the L10 life concept and in many cases limit bearing life.

Understanding L10 bearing life

All gear applications, excluding those of spur and double helical gears, generate a combination of radial and axial loads. These loads are carried by the bearings located within the gear unit.

One general equation is used for this conversion: (1) Fr is the Radial load component [N] Fa is the Axial load component [N] The factors X and Y are respectively known as the Radial factor and Thrust factor. These factors are bearing specific and are found in bearing manufacturers’ catalogues. The basic life equation, as given in equation 2, represents all roller element bearings as covered in ISO 281. (2) Where L10 is the basic life rating [ x106 rev] C is the basic bearing load [kN] P is the equivalent dynamic load [kN] n is the bearing specific life exponent

n = 3 for ball bearings

n = 10/3 for roller bearings

L10 life is not commonly used as it is expressed in millions of revolutions. This is a cumbersome way to deal with bearing life. Hence, L10h life is commonly used, as it is expressed in the easier to use from of hours of operation. The L10h life is calculated using equation 3 or 4 below. (3)

When calculating the L10 life of a bearing, this combination of axial and radial loads must be THE SOUTH AFRICAN MECHANICAL ENGINEER

(4)

VOL 62

August 2012

POWER TRANSMISSION

deterioration of L10 life with an increase in the axial load.

Where L10h is the basic life rating [hrs] L10 is the basic life rating [ x106 rev]

2. Taper roller bearings show a moderate increase in bearing life with an increase in the axial load.

C is the basic bearing load [kN] P is the equivalent dynamic load [kN]

3. For Helical gearing, where spherical roller bearings are preferred, the axial load should be less than 20% of the radial load. Otherwise the use of taper roller bearings should be considered.

n is the bearing specific life exponent N is the rotational speed of the bearing [rpm]

Case study

Consider a common conveyor application of a gear unit with a shaft supporting two gears, a pinion and a wheel. For a given power and speed, the L10 bearing life was calculated for varying axial and radial load contributions. The load conditions were varied using the helix angle to alter the axial load contribution, while the radial load remained nearly constant, due to the power and speed remaining constant. The bearing life was calculated for both spherical and taper roller bearings, as these are most commonly used within gear units.

It is also interesting to note that there exists a percentage axial load point at which both spherical roller and taper roller bearings will theoretically achieve the same L10 bearing life. This is important to gear unit manufacturers, as both the loading conditions, radial and axial load contributions, and the type of bearing used, need to be balanced to provide not only the most efficient mechanical solution, but also an economical one.

Gear Unit bearing life

The data for the case study was populated onto the graph, figure 1.

The L10h life typically referred to specifies the life of a single bearing and not that of the gear unit.

The case study yielded four pertinent facts:

The L10h life for a gear unit assembly consisting of n number of bearings is calculated as expressed in equation 5.

1. For spherical roller bearings there is a rapid

4. For Bevel gears, with high axial loads, the preferred bearings should be taper roller bearings.

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

POWER TRANSMISSION

(5) Where L10h(ass) is the L10h life for the gear unit as an assembly [hrs] L10h(1); L10h(2); L10h(n) are the L10h life for the individual bearings in the assembly [hrs] The standards that gear unit manufacturers use, such as AGMA, are generally and historically quite lax with regards to bearing life requirements. The minimum criterion for an L10h bearing life at a mechanical service factor of 1.00 is as low as 5 000 hours. For a continuously operational gear unit this amounts to 6.9 months of operation. Often the bearing life specified is 50 000 hours to 100 000 hours. This equates to 5.71 years to 11.42 years of continuous operation. However, this too may not be realistic.

Figure 1: L 10 bearing life with percentage axial load

So what should a conveyor gear unit end-user specify? Do all the gear unit manufacturers provide the same calculated bearing life? It would be preferential to end-users to specify the recommended minimum individual L10h bearing life in accordance with ISO 281.

Gear unit assembly bearing life versus individual bearing life

A triple reduction, right-angled gear unit, such as those commonly used for conveyor applications, has eight bearings within its assembly as depicted in figure 2. The individual L10h bearing lives are as follows: Bearing

L 10h life

174,248

165,598

125,120

61,166

131,731

111,276

993,794

26,713,820

(6)

If the above unit were to be adjudicated on its individual bearing life, it would be stated that the bearing life of bearing 4 is the limiting life at 61,166 hrs. How realistic is this assumption? However, should one consider the gear unit assembly bearing life, as expressed in equation 5: The L10h life for the assembly is calculated as being as low as 33,086 hours. This however, is also unrealistic, as this states the unit will only have 3.78 years of continuous operation.

The a23 factor

The a23 life adjustment factor was first introduced by ISO in 1977. The a23 life adjustment factor adjusted for material and lubrication. The adjusted L10h life is known as L10ha23 or L10ha bearing life.

Table 1: Individual L10h bearing life for a typical conveyor gear unit

The a23 factor was originally introduced due to the upgrading of steel quality over the years improving the bearing lives achieved. It was felt that lubrication conditions should also be taken into account. Hence, the value of the a23 factor is a function of the viscosity ratio. The viscosity ratio is defined as the actual viscosity (v) divided by the viscosity

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

POWER TRANSMISSION

on the lubricant used. The actual viscosity is determined at the operating temperature of the gear unit. Figure 4 shows the operating viscosity versus the operating temperature. The a23 life adjustment factor is determined using figure 5. The value for the a23 factor can vary between 2.5 and 0.45. An a23 value of 2.5 represents ideal lubrication conditions and material.

Figure 2: Typical conveyor gear unit layout

required for adequate lubrication at the operating temperature (v1). This ratio represents the size of the oil film thickness relative to surface irregularities of the bearing elements. The required viscosity is determined from figure 3. The actual viscosity of the lubricant is dependent

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

With regards to a typical conveyor gear unit, the a23 life adjustment factor can vary from 2.50 at the input to 0.67 at the output. With reference to figure 3, it can be seen that for a smaller bearing, mean diameter and higher rotational speed, as experienced on the input shaft of a gear unit, the minimum required viscosity is lower. The converse is found with regards to the output shaft. Because the actual operating viscosity is constant within the gear unit, it will be found that the viscosity ratio for the input shaft of a gear unit will be substantially higher than that of the output shaft. This results in a lower a23 life adjustment factor for the output shaft than that of the input shaft. This is typical for most conveyor gear units operating at bearing

August 2012

POWER TRANSMISSION

temperatures of 60 째C to 90 째C with either ISO VG 220 or ISO VG 320 gear lubricating oil. This means that on the output line of the gear unit, the L10h life exceeds that of the L10ha life. However, it should also be stated that the a23 factor was superseded by the aISO factor. At its conceptualization, the a23 life adjustment factor only took into account material of the bearing and the lubrication of the bearing at a standard cleanliness condition. The reason for the change of factor was to take contamination of the lubrication Figure 3: Minimum required viscosity, v into account. It was found that the effects of lubrication contamination may have profound effect on the operation and as on the achieved bearing life were indeed significant. a result the actual life achieved by the bearings. This is seen in the situation where abrasive wear Operational factors, such as alignment of the motor due to contamination changes the load zones of and the gear unit at installation and reinstallation the bearing, resulting in a reduced load carrying may result in large amounts of strain of the bearing capacity and reduces achieved bearing life. Hence, components due to an alteration in the loading of due to the nature of industrial applications and the said bearings, resulting in a reduced ability to the operating environment, especially that of the carry the applied loads, as discussed previously. conveyor, the a23 factor cannot fully adjust for This may also deteriorate the bearing life achieved. lubrication effects within a gear unit. The ISO 281 concept of L10 life does not include these operational factors. Most bearing failures exBearing life and the conveyor industry Most project specifications for conveyor gear units perienced on conveyor gear units are not the result specify an L10ha life of 100 000 hours, this equates to more than ten years of continuous operation. This L 10ha bearing life specified refers to the lives of individual bearings within the gear unit, and not the bearing life of the gear unit as an assembly. It is conventional for conveyor gear units to have splash lubricated bearings. Hence, at start up the bearings are essentially starved of lubrication, as is on certain gear units. This starvation at a start-up over a period of ten years

Figure 4: Actual operating viscosity, v

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

POWER TRANSMISSION

larger and larger units are required for the same conditions. However, this may have the following implications: • Economics: a larger unit costs more and has higher maintenance costs. • Loading: The load applied to the larger unit, with larger bearings, may be too light. Resulting in the deterioration of the bearing lives.

Figure 5: a23 Life adjustment factor graph

of fatigue. It is generally found that if a bearing does not fail due to the effects of these operational factors, the bearing life achieved by the said bearing can greatly exceed the calculated L10h life. With the increased requirements of bearing life,

• Installation: The larger the gear unit the more difficulty arises with regards to the installation, and alignment of the gear unit. This increases the chances of bearing life reduction due to misalignment. It has been found that although larger bearings lives are being specified, requiring larger gear units, the time between bearing failure has not followed the same trend. So although the L10h life has increased, the practical factors discussed in this paper lead to the same failures as on the previously smaller gear units. Many end users spend increasing amounts on ever larger gear units. But are the manufacturers all supplying the same bearing life? It is in the best interests of gear unit end-users to specify one common format for bearing lives. It is the recommendation of this paper that the bearing life format be the ISO L10h bearing life, and a specified bearing life value of 40 000 hours. This value is equivalent to the current commonly specified value of 100 000 hours L10ha23 life. However, it does not allow for life adjustment factors, which as discussed in this paper, and do not adequately adjust for the practical operating conditions experienced in reality.

Conclusion

While conveyor gear unit costs increase, it is in the best interests of gear unit end users to specify one common, consistent format for bearing lives. It is the recommendation of this paper that the specified bearing life be 40 000 hours L10h basic, which is equivalent to the current commonly specified value of 100 000 hours L10ha23 life. Note: This paper has been condensed due to space constraints. The author is Lorinda Lakay. David Brown Gear Industries. This paper was first presented at Beltcon 16 held in Johannesburg in 2011 and copyright is vested with the IMHC. Enquiries can be made through the website; www.beltcon.org.za

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

PUMPS, PIPES & VALVES Most thickener plants on mines are today equipped with peristaltic pumps

Hose Pumps Firmly Established Peristaltic hose and tube pumps have long been established in dosing applications across various industries, especially applications involving abrasive, highly corrosive, viscous, high density and shear sensitive products. consultant for Verder Pumps South Africa (VPSA), about the ever-increasing application of peristaltic pump technology in mining. “Globally the use of peristaltic pumps has grown more than any other type of pump on the market,” he says. “This can be ascribed to its wide range of applications. “For example, it has now become a given fact that thickeners in mine material processing can only be pumped effectively by peristaltic pumps,” say Daan. “The solids content in thickeners are often as high as 70% and no other type of pump can move such a dense material effectively. A centrifugal pump, for instance, can do a solids content of up to about 50% before it starts failing to get material through.”

Gentle but tough Daan Louw of Verder Pumps SA

n the beginning, the peristaltic pump was mainly adopted by industries such as water and waste water, the food and beverage, chemical, bio fuel, print and packaging and the ceramics industries. However, as this pump’s technology improved over the years, it also started making inroads into the mining industry, not only for dosing purposes, but also to convey thick slurries and thickeners.

The solids content in thickeners are often as high as 70% and no other type of pump can move such a dense material effectively Growth

“SA Mechanical Engineer” speaks to Daan Louw, a

In addition, the peristaltic pump has a very-gentle pumping action which does not damage the pumped material which is an advantage in many applications which involve shear sensitive products such as food, beverages and yeasts. Regardless of the role, the peristaltic pump provides a high level of reliability and cost-effectiveness and often lasts longer than other type due to its design where the hose is the only working part in contact with the fluid. This reduces the cost of maintenance and the associated costs of downtime. In the past, a big problem was that many customers simply did not fully understand the technology of peristaltic pumps, but this has changed significantly. “The fact that most thickener plants on mines are today equipped with peristaltic pumps is a clear indication,” Daan says. “Many engineers knew about peristaltic pumps but didn’t understand the

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

PIPES, PUMPS & VALVES

pipeline circuit for a peristaltic pump application based on a centrifugal pump principle, which just doesn’t work.

Overcoming problems

“In the ten years VPSA has been distributing peristaltic pumps in South Africa we’ve spent a lot of time and effort to change the mindset by teaching and showing engineers how these pumps work,” Daan adds. “We’ve also ‘customised’ the pumps for local conditions as we’ve come across specific problems, especially in applications where these pumps were not used before.” The principle of peristalsis is to pump products through a flexible rubber hose by two shoes on a rotating axis, in the same way blood, food and oxygen is pumped around the human body. A peristaltic pump in a slurry application One of the more common problems associated with these pumps is where Many engineers knew about peristaltic pumps but didn’t a cavity is formed in the pipeline just as the presunderstand the hydraulics around these pumps because sure shoe leaves the hose as a result of squeezing to push the material towards the delivery outlet of it was never taught at university the pump. The back-pressure of the material in the hydraulics around these pumps because it was never pipe causes a pulsation which results in vibration taught at university. The result is they’d design the and hammering in the system, damaging the hose and reducing its lifespan.

Solutions

To overcome this pulsation, Daan over the years has developed several solutions. “It’s a bit like a locomotive is pushing wagons uphill, when it suddenly stops, reverses and the wagons also start rolling back downhill to hit the loco with huge impact. This is what causes pulsation in a pump situation, sometimes so big it can burst the hose or the pipe near the discharge end of the pump,” he explains. “We use a locally-developed system whereby we fit either an inlet pulse accumulator (IPA) or a pulsation damper (PD) unit which can operate at variable flow rates and can be used on all types of materials,” says Daan. “ Our system has proven successful in various applications on several plants. We have a software programme to calculate pump duty for each specific application to determine beforehand whether an IPA or PD will be necessary or not.”

Into Africa

Like many other South African companies, VPSA is increasingly being contracted to undertake projects on mining operations in African countries like Zimbabwe, Zambia and the DRC. “We recently released the biggest peristaltic pump available in the market, our Verderflex 125 and several of these have been installed on a mine in the DRC,” says Daan in conclusion. Laetitia Möller, Verder Pumps SA, Tel: (011) 704-7500, Email: laetitia.moller@verder.co.za

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

PUMPS, PIPES & VALVES

Pipe Laying, The Right Way… Until a few years back, pipeline contractors made do with makeshift modified machinery in order to lift sections of pipe into trenches, resulting in many stories of machinery such as bulldozers, excavators and mobile cranes toppling over while lifting large pipes sections into position. Today there are dedicated machines designed to make pipeline construction a much more efficient and safe operation than in the past.

series of dedicated pipelayer machines, designed and made by Volvo, is now available in South Africa through Babcock Africa Services. “SA Mechanical Engineer” joins the launch of the product in South Africa as three PL4608 pipelayer machines are handed over to Basil Read, one of the leading pipeline contractors in Africa.

Marius Heyns, CEO of Basil Read

“There’s no doubt in my mind that these dedicated machines, the first to be imported into South Africa, will change the concept of pipelaying for ever,” says David Vaughan, sales director at Babcock.

These dedicated machines, the first to be imported into South Africa, will change the concept of pipelaying for ever

David Vaughan, sales director at Babcock

Representing one of the most significant innovations in the past 80 years, the patented, Volvo pipelayer represents a major step forward”

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

PIPES, PUMPS & VALVES

and red light bars are mounted at either side of the boom tips, reflecting the state of the load.”

Safety

Unlike conventional pipelayers, which are inherently unstable with the boom mounted outboard on a bulldozer side frame, the Volvo pipelayers have the boom located inside the tracks, closer to the machine’s centre of gravity, resulting in greater stability. The boom provides a clear view to the work area, but also one to the load block at all heights and into the trench. The hydraulically-elevating cab improves overall visibility, especially into the trench increasing site safety. Standard on the PL4608 model is the hydraulically variable undercarriage which expands by 500 mm, making it extremely stable in lowering and laying-in operations. With machine tipping a constant threat on pipeline sites, machine stability is non-negotiable. A unique load management system enables the operator to see exactly what he can safely pick up. Real-time information is displayed on an in-cab monitor, together with visible and audible warning signals when the safe load limit is being reached. Even when working on steep slopes, the system measures all the relevant angles as well as the load on the hook to notify the operator of the safe working range at all times.

The Volvo pipelayers have the boom located inside the tracks, closer to the machine’s centre of gravity, resulting in greater stability “Although we’re one of the smaller of the big five contractors, it is technology like this which enables us to do everything they can do.”

Water project

The pipelayers will initially be used by Basil Read subsidiary Valente Bros. on the Olifants River Water Resources Project, where the company will be laying approximately 40 km of welded steel pipelines on behalf of the Trans-Caledon Tunnel Authority for Phase 2 of the project. This entails bulk water transfer pipelines and a storage reservoir intended to supply bulk water for domestic and mining use in the Limpopo Province. “Key to making the decision to purchase the fleet was the enhanced safety features which come as standard with the Volvo PL4608 pipelayers,” says Roelof van der Merwe, managing director of Plant at Basil Read. “The wide working platforms reduce the risk of tipping while highly visible green, amber

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

Moving between sites

For ease of transport, the counterweight can be lowered to the ground and removed using a standard, hydraulic counterweight removal system. The PL4611 model features two track frame-mounted counterweights that can easily be lifted off with the help of the boom and winch with retractable jacks providing complete machine support for removal of the track frames. After the frames are hydraulically disengaged, heavy lifting eyes on the track frames provide optimum lifting points for removal and reassembly. Removal of side track frames and rear counterweight reduces the machine weight and width to fulfil on-road transportation regulations. Once raised on the hydraulic jacks, the machine can be lowered directly onto a trailer. David Vaughan, Babcock, Tel: (011) 230-7300, Email: david.vaughan@babcock.co.za

August 2012

OPINION

Soapbox On his rounds, Kowie Hamman, our Editor, is conducting an informal survey on the lighter side of engineering. We follow up from last month with two pertinent questions. Do you feel mechanical engineers are paid enough?

Brian Volk of PHC Projects: Not in general. Phildy Schlotz of DRA: Yes, I think so, engineers

What do you drive now and what would you drive if money was no object?

Brian Volk of PHC Projects: A Honda Accord now but I’d probably like to own an E Type jaguar if I could find a good one.

have a broad spectrum of remunerations, so it depends which industry you’re in. I think there are huge opportunities in engineering, it is a noble occupation.

Phildy Schlotz of DRA : We now drive a Landrover. (chuckle) I’ll just get another Landrover, for sure!

Tom Esterhuizen of Tom Esterhuizen & Associates: It’s difficult for me to say, but

Tom Esterhuizen of Tom Esterhuizen & Associates: I now drive and Audi A6 and I’m

Thalefang Mtombeni of Schaeffler: No!

Thalefang Mtombeni of Schaeffler: I drive a Ford Focus, but if I had the money I’d be driving a Mercedes SLK.

despite some room for improvement, I think generally the remuneration is not too low when you’re self employed, but young engineers working for a salary can probably be improved.

Izak van Niekerk of Bell Equipment: Yes, although

one can never be paid too much!

Konnie de Boom of Megchem: In general,

considering the present economic climate, I’d

very happy with it, I don’t want any other car. I might consider going smaller to Audi TT, but that’s about it.

Izak van Niekerk of Bell Equipment: My wife Konnie de Boom and I drive matching short wheel base Pajeros-they are good for potholes and still small enough for the city! I like the Porsche Cayenne.

On par with your needs

Technical Expertise - Service - Quality - Training • Bearings • Couplings • Chains • Sprockets • Pulleys • V-Belts • Gearboxes • Geared Motors • Electric Motors • Oil seals • Lubricants and cleaners • Many other allied products

Not just a bearing shop After Hours National Hotline: 083 250 9191 BBBEE Level 3

For your FREE GIFT, scan

or visit www.bearings.co.za

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

EDUCATION

On a Par

Engineering students at the West Campus of the University of the Witwatersrand, Johannesburg (Wits) are benefiting from a newly-constructed and modernised engineering library following a R200 000 donation from PPS, the financial services provider focused on graduate professionals.

ccording to John Marsden, national sales director at PPS, the company is thrilled to donate this money that went towards the much-needed revamping of the engineering library located in the Chamber of Mines Building. “The donation has been used to purchase computer workstations for students, a fully-equipped Information Skills class room (electronic class room) and the provision of electronic resources alongside traditional printed materials. “Access to the latest technology and resources are vital foundations for the provision of a quality education, especially for engineering students as South African is currently suffering from a severe engineering skills shortage,” says John. He adds that the engineering library supports learning, teaching and research practices across the complete range of five schools in the Engineering Faculty including Mining Engineering, Electrical and Information Engineering, Chemical and Metallurgical Engineering, Civil and Environmental Engineering, as well as Mechanical, Industrial and Aeronautical Engineering. Professor Beatrys Lacquet, Dean of the Faculty of Engineering & the Built Environment says that the library provides a full range of educational services to 150 academics and researchers, and approximately 4 000 engineering students at undergraduate and post graduate levels. www.pps.co.za

Electra Minning - 10 to 14 September 2012

In the midst of relative doom and gloom, one entity that’s unaffected is Electra Mining 2012. The organisers are talking about putting people in passages, hiring marques - we’re thinking they could do some floating pontoons on the lake? By all accounts, this exhibition and conference is set to be a humdinger. Make sure you get there and don’t forget to look up “SA Mechanical Engineer” in the soapbox area where we will be teaming up with the SA Institution of Mechanical Engineering to talk all things engineering. Specialised Exhibitions, Tel: 011 8351565, www.electramining.co.za

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

MARKET FORUM

Eco- friendly solutions

Water jet-cutting and profiling expert AquaJet Profiles supplies highlyspecialised precision-cutting services for complex applications within various industries in South Africa, ranging from aerospace and petrochemical, to architecture and mineral processing. Johannesburg-based AquaJet uses the powerful cutting force of water and garnet sand to create a unique cutting tool known as a jet, explains company director Preeshan Naidoo. “The AquaJet cutting process involves the use of ultra high-pressure water at 3 500 bar, which is pumped through a diamond jewel with a 0,2 mm diameter hole – accelerating the water to Mach 2,5. The abrasive garnet sand is then introduced into the stream of water, and is also accelerated to Mach 2,5.” Preeshan notes that the greatest advantage of aqua-jetting is that it is able to cut material with pinpoint accuracy, without interfering with the material’s inherent structure. “Unlike plasma cutting, aqua-jetting entirely eliminates the heat affected zones (HAZ) during the cutting process; thereby, enabling metals to be cut without harming or changing intrinsic properties. The process is essentially the same as water erosion found in nature, but greatly accelerated and concentrated.” Aqua-jetting can be applied to almost any manufacturing material. “Aquajetting is particularly-beneficial in applications where expensive alloys such as copper, aluminium and titanium need to be cut with complete accuracy, and minimal waste. The precision of our cutting is based on our proximate settings and fine tuning, holding tolerances between 0,09 mm to 0,35 mm, and only 75 percent loss per millimetre.” AquaJet Profiles Preeshan Naidoo, Tel: (011) 908-5550, Email: info@aquajetprofiles.co.za, Web: www.aquajetprofiles.co.za

Ease of scalability

Watson-Marlow Bredel SA has launched the new Apex range of pumps for dosing, metering and transfer duties between 2.8 and 1 200 litres per hour.

from lime dosing and slurry transfer to handling food and beverage products,” says Watson-Marlow Bredel SA general manager, Nico van Schalkwyk.

Robust, reliable and flexible, Apex sets a new standard for lowering lifecycle costs in a broad range of tough industrial applications. Unlike other pump types, Apex hose pumps have no expensive wearing components such as seals, valves, membranes, stators, rotors or glands to maintain.

“Along with a two-year warranty, customers purchase safe in the knowledge that these pumps are manufactured by Bredel, the world’s largest manufacturer of hose pumps, with more than 100 000 models in operation around the globe,” he concludes.

The pumps are perfectly suited for handling difficult fluids: corrosive, viscous, shear-sensitive, gaseous, crystallizing or even fluids with a combination of these properties. “The all-round performance of the Apex models 10, 15 and 20 means they are suited to applications ranging

Among the many benefits of the new pumps is ease of scalability. While Apex offers optimum performance for low transfer applications, easy upgrades are achievable without having to buy a new pump, should process requirements change. Watson-Marlow, Nico van Schalkwyk, Tel: (011) 796-2960,

On top of things ABB was recently awarded a fiveyear ABB Full Service contract with Namibia Custom Smelters (NCS), to manage and improve all maintenance activities at their copper smelting and converting plant in northern Namibia. The full service total plant maintenance agreement includes the transfer of NCS maintenance and reliability staff to ABB, as of 1 July 2012.

ABB’s Full Service model, which involves the complete management and operation of a plant’s maintenance function, development and implementation of expert measures to improve productivity and equipment reliability, will be employed at NCS. In this manpower-intensive environment, ABB’s performance agenda will include a strong focus on Occupational Health and Safety (OHS) standards for the workplace. NCS is located in Tsumeb, Namibia,

approximately 425 km north of the capital, Windhoek. The plant, which was commissioned in 1963, is owned by Dundee Precious Metals Inc. of Canada. It consists of two primary smelting furnaces, three converters, and has an annual production capacity of 200000 tons of copper concentrate from the treatment of complex copper concentrates containing gold, silver and arsenic. The smelter is one of only a few in the world which is able to treat arsenicbearing copper concentrates. Both blister copper and arsenic trioxide are produced from the concentrates; the copper is then delivered to refineries for final processing, while the arsenic trioxide is sold to third party customers.

ABB, Sibongile Metsing, Tel: (010) 202-5029, Email: Sibongile.metsing@za.abb.com, Web: www.abb.com

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

MARKET FORUM

Handling automotive assembly In automotive assembly plants, components, engines and completed vehicles are moved from plant to plant and these distances often mean extensive travelling time for one container movement. This results in assembly delays and extensive wear and tear on conventional forklifts, which negatively affects productivity. BLT SA supplies a range of container and component handling equipment designed for optimum efficiency, reduced operational costs, enhanced safety and minimal maintenance in automotive assembly plants. An important advantage of this system is that it utilises all parts of the yard and operates on pavements and in restrictive areas where conventional equipment cannot go. This mobile container handler turns in tight spaces and is also able to travel inside warehouses and under awnings. The Mobicon allows the movement and supply of components, engines and completed vehicles to and from each plant and line, in containers or on flat beds, as well as specialised racking systems.

The Mobicon mobile container handling system from BLT SA is designed for efficient, safe and versatile container and product handling, in and around automotive assembly plants.

By having only one container or product supply movement, time savings are significant. There is no longer the need for automotive plants to run a fleet of conventional forklifts. Other advantages for the Mobicon in automotive assembly include easy handling of ramps and speed bumps, reduced on-site congestion and minimal damage to stock normally caused by long forklift and container handling truck runs. Loads are no longer handled outside in wet weather conditions and container handling schedules are now much more efficient. BLT SA, Clinton van den Berg, Tel: (031) 2748270, Fax: (031) 205-8002, Email: Clinton@ biglift.co.za

Moral high ground Artic Driers offers Condensate Managements Systems manufactured in Europe by Sepura. These systems take the thousands of litres of oily waste water generated by the dryer filter and

Meclift variable reach trucks are also suitable for use in automotive plants. These units have a 16 ton lifting capacity and at full reach of 2.5 metres, they can safely lift 7 tons. Meclift reach trucks are able to go into a container for efficient, swift and safe container stuffing, de-stuffing and are also designed for handling all types, sizes and shapes of goods. These 16 ton units are able to stack empty, 6 metre containers, three high.

receivers and extract the low volumes of compressor oils trapped in the condensate stream. The extracted compressor oils are retained for proper waste disposal and the cleaned waste water is allowed out legally to the normal drain systems. A few litres of oil will wreck a wetland

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

environment very quickly. From a legal and moral point of view, illegal dumping of contaminated waste condensates is no longer acceptable In todayâ&#x20AC;&#x2122;s environment itâ&#x20AC;&#x2122;s essential to maintain the lowest operating cost, conserve profits and reduce staff time

MARKET FORUM

Welder Identification System V a l v e retrofit service PSV Mitech can offer a retrofit service where it will fit new internals and top works to an original valve body. In many cases when an existing valve needs to be replaced in a plant, the valve body is still in good condition but the trim is no longer suitable, and in addition, the actuator and positioner need to be updated.

In a move to ensure consistent high quality of welding and introduce transparency and accountability in the industry, the Installation and Fabrication Plastics Pipe Association (IFPA) has issued all of its welders with identification stamps.

In these cases PSV Mitech trims will be designed to suit the application, and can be selected from the complete range right up to the energy dissipating disk stack. Materials are chosen to ensure safe operation and long life.

According to IFPA Chairman, Mike Smart, its welders were required to be recertificated before they were issued with their unique stamps. “The annual recertification of welders was instituted by Plastics SA in 2000 in an effort to better ensure quality of practical work. However, in September 2010 it was decided that IFPA members would have the benefit of only having to recertify their welders once in a three year renewal cycle, while non-IFPA members would be required to certify their welders annually”, says Mike. As part of IFPA’s mandate, a mechanism was developed whereby a welder could be traced back to every weld he ever performed. Thus a Welder Identification System was implemented by Plastics SA and IFPA in 2010. “Since then, every IFPA welder has been issued with a unique number, printed on an identification card, along with

involvement to a minimum. In order to achieve to this objective, an investment in compressed air monitoring is the fastest way to achieve power reduction targets and achieve a more efficient and eco-friendly compressed air system. Artic Driers International is a family-

his photograph. Each IFPA Member Company is expected to complement the system of traceability with the use of a stamp on each weld, displaying the IFPA company number, the unique welder number and the IFPA logo”, Mike explains. The stamp is made of special hardened steel and can be used next to a weld if the weld surface is too small. Members are tasked with the responsibility of ensuring the stamps made for their welders are kept up to date; to verify the specific discipline that the welder has been qualified for and control employee activities such as moonlighting. SAPPMA, Web: www.sappma.co.za

owned specialist supply company and is the sole Southern African distributor for air treatment products manufactured by SPX Dehydration, Pusan S. Korea. The company also represents BEA Filtration high quality inline filtration, CS Instruments suppliers of air monitoring

Below 150 mm or 600# the cost of retrofitting generally will not be justifiable, but with larger sizes and high pressure rating valves, it becomes progressively more worthwhile. PSV Mitech recently rebuilt eight 200 mm valves for an oxygen plant in a large petrochemical factory. The material used for the plug, seat and retainer was Monel K500, and the bonnet was manufactured in stainless steel to suit the bodies. New actuators and positioners were fitted to the valves. The object of the exercise was to improve safety in the plant and to provide a valve with tighter shut off. PSV Mitech, Greg Walker, Tel: (011) 657-6000, E-mail: gregoryw@mitech.co.za Web: www.mitech.co.za

instruments for professionals, and BryAir dehumidification products. Artic Driers, Allen Cockfield, Tel: (011) 425-3484 www.articdriers.co.za

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

MARKET FORUM

Pump protection unit The SkidRat pump protection unit is attracting attention in the industry as an ideal way to prevent pumps from being damaged by sediment at the bottom of ponds. This innovative unit was developed by UAT in Australia and is exclusively distributed throughout sub-Saharan Africa by Xylem (formerly known as ITT Water & Wastewater South Africa). Harnessing a pontoon approach, the SkidRat features modular floats that lend this unit to unlimited configurations to suit each pump and application. The tough and durable unit is chemical resistant and can be handled by cranes, excavators, dozers, trucks and trailers. The Australian developed SkidRat is now available from Xylem and offers an ideal way to prevent pumps from being damaged by sediment at the bottom of ponds.

Xylem, Lee Vine, Tel: (011) 966-9300, Web: www.xylemwatersolutions.com

Substantial savings Atlas Copco recently launched its new AQ oil-free, water-injected screw compressor range. "With an installed motor power from 15 to 30 kW and exclusively available with Variable Speed Drive (VSD) technology, the new AQ 15-30 Class 0 certified oilfree compressor range offers substantial energy savings and high operational efficiency," says Atlas Copco South Africa Business Line Manager - Industrial Air, Charl Ackerman. “This new product range, available in four models, including air- and watercooled variants, brings reliable, ISO 8573-1 Class 0 certified, oil-free air to the most sensitive below 30 kW applications including medical, pharmaceutical, electronics and >8bar pressure applications,” explains Charl. The AQ's water-injected screw technology is not only 100% oil-free for optimum air quality, but thanks to its integrated air treatment, the AQ offers substantial energy savings and ensures optimum operational efficiency, reliability and air quality. The introduction of Atlas Copco's exclusive VSD technology, matching the compressor output to the air demand,

leads to energy savings of 35% on average. Running a VSD compressor means more compressed air for less power consumed with lower energy costs as the direct result. Next to this high flow per energy consumed, the AQ 15-30 VSD offers noise

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

levels as low as 67 dB(A). Therefore, the AQ is the perfect ‘WorkPlace Air System’, that will effortlessly fit onto every work floor. Atlas Copco, Charl Ackerman, Tel: (011) 8219000, Web: www.atlascopco.co.za, Email: charl.ackerman@za.atlascopco.com

MARKET FORUM

The right connection

Couplings are primarily used to connect two pieces of rotating equipment. They are chosen for their misalignment and/ or flotation capabilities and can further influence machine performance by allowing for easy disconnection, absorption of shock loads, protection against overloads, vibration reduction, etc. Voith Turbo South Africa is a specialist supplier of a wide range of high quality shaft-to-shaft connecting couplings that provide reliable and economical solutions across industry.

“Our coupling footprint covers all industry segments,” says Voith Turbo South Africa Product Manager - Shaft to Shaft & Falk Couplings, Varma Parag. The coupling range from Voith Turbo, includes their unique resilient and membrane coupling ranges, which are well complemented by Falk Gear, Grid and the Wrapflex elastomer coupling. “Every application is different and whether the demand is for absorption of shock load or for high torque in a small space, our expert product knowledge and industry

experience enables us to offer the right coupling solution to suit the application. Professional advice is offered by our very experienced product specialists. After sales service is provided by our trained service team who analyse, repair, maintain and overhaul couplings in accordance with Voith quality standards, for lowest cost of ownership and optimal peace of mind”, concludes Varma. Voith Turbo, Varma Parag, Tel: (011) 418-4000, Email:varma.parag@voith.com

Two prestigious contracts

The first of the 12 purpose-built 1,2 MW main pump motors for NamWater’s Von Bach-Windhoek Transfer Capacity Project is shown here ready for dispatch from ACTOM Electrical Machines’ Benoni plant.

Actom Electrical Machines recently won export contracts worth a total of R14,5million from two prominent customers – an international pump manufacturer based in Italy, and Namibia’s water supply authority NamWater.

the 1LA1 series previously on offer, comprises totally-enclosed fan cooled (TEFC) motors in the 200 kW to 1100 kW power range, with frame sizes of between 355 and 500 and voltages of 3,3 kV, 6,6 kV and 11 kV.

The pump manufacturer is KSB Pumps, which placed an order with Actom Electrical Machines in January this year for a total of 44 medium and low voltage motors – all destined for use in the water treatment plant currently under construction at Eskom’s new Kusile coalfired power station near Delmas in Mpumalanga.

The contract for NamWater is for the manufacture and supply of 12 customised high efficiency main pump motors which are to be installed at the Von Bach-Windhoek Transfer Capacity Project, which is aimed at expanding the water supply system for Windhoek.

A noteworthy aspect of the medium voltage motors portion of the order is that it represents Alstom’s first large contract for motors in their new MS4 series of high-spec medium voltage cast-iron motors, which were launched into the market early this year. The MS4 series, which have replaced

The motors, which will be purpose-built to NamWater’s stringent specifications, are 1,2 MW 4-pole 690 V Unibox units designed for variable speed drive applications. Actom Electrical Machines, Paul Lepora, Tel (011) 899-1114, Fax (011) 899-1371 E-mail paul.lepora@actom.co.za, Web: www.actom.co.za

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

MARKET FORUM

Safety of supply

strategically-positioned depots, one being the Alrode Fuel Depot in Alberton, as well as the accompanying Beryllium site, both of which were previously owned exclusively by Sasol Oil; and the other being the Waltloo Depot in Pretoria, which was previously owned exclusively by BPSA. Both depots will now be owned by the two companies in equal shares, which gives the companies equal access to the storage capacity of the depots. A joint venture agreement, read in conjunction with an operating agreement will govern the joint venture, generally, as well as the operations within the co-owned facilities.

Bernard Klingenberg and Gerard Derbesy

The Competition Commission has approved a merger application filed jointly by Sasol Oil and BP Southern Africa (BPSA), in terms of which the approval

of a proposed joint venture between the two companies was requested. The unincorporated joint venture will comprise the co-ownership of two

“Meeting customers’ needs is a key priority for us; and we can now reach customers quicker and more efficiently in the northern areas. We’re pleased that BP Southern Africa saw the potential value in this partnership,” says Bernard Klingenberg, Sasol Group Executive, South African Energy. BP, Glenda Zvenyika, Tel: 082 678 8450

On the Move

Gert Albasina Gert Albasina has been appointed senior QA manager at PSV Mitech’s head office in Elandsfontein, Johannesburg.

Johan Hills Johan Hills has been appointed CNCmachine programmer at PSV Mitech’s head office in Elandsfontein, Johannesburg.

Barry Elliott Rockwell Automation, has appointed Barry Elliott as its new Managing Director for its sub-Saharan Africa office.

Mario Marais Mario Marais has been appointed General Manager: Operations for a.b.e. Construction Chemicals, part of the Chryso Southern Africa Group.

Hendrik Strydom Hendrik Strydom has been appointed director at Liviero Plant.

Bernard Rabé Watson-Marlow Bredel SA has apointed Bernard Rabé new Cape Town area manager.

Index to Advertisers Artic Driers

Axiom Hydraulics

Inside Front Cover

Bearings International

KDP Services

Schaeffler

Outside Back Cover

Kira 36

SEW 4

KSB Pumps

Spectra Carbide

Inside Back Cover

Bonfiglioli 10

Multi-Alloys 30

Sprag Components

Busch 18

Multotec 16

Verder 38

CMG 27

PPS 11

Voith 22

Electra Mining Africa

Pump & Seal

Walter Meano Engineering

24,25

Engen 19

Rand-Air 14

Weir Minerals

Hansen

Outside Front Cover

Rodecon 32

Zest 20

Horne 26

SAEE 23

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

EXPERIENCE THE POWER OF TURNING VISION INTO REALITY. Engineer what you envision.

Spectra Carbide Tooling Technology (PTY) Ltd. 24 Desmond Street, Korsten, Port Elizabeth PO Box 2631, North End, 6056 Tel: 0860 23 23 23 Fax: 0860 33 22 33 spectra@spectra-sa.co.za www.spectra-sa.co.za

www.walter-tools.com THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012

Reliability. Made by Schaeffler Schaeffler is the bearing specialist in the field of mining. For excavating, conveying and processing, our service accompanies the bearings throughout their entire life cycle. Both our standard range and special bearing designs are tried and tested in the toughest of environments and offer ideal solutions to the most challenging applications. Three examples: For time-saving bearing replacement in hard to reach locations, our FAG split spherical rolling bearings minimize downtime saving you time and money. In conveyors, our new FAG Black Series is interchangeable according to JIS and has Durotect® B coated bearing rings for improved corrosion resistance. And the FAG SmartCheck, an innovative sensor for real time monitoring, provides greater safety for machines and plants.

936 011

For more information please contact: Schaeffler South Africa – Industrial 1 End Street Ext. · 2000 Johannesburg · South Africa Phone +27 11 225 3000 · Fax +27 11 225 3092 tlhalefang.mtombeni@schaeffler.com

THE SOUTH AFRICAN MECHANICAL ENGINEER

VOL 62

August 2012