The Bulletin – October 1981

THE BULLETIN

Journal of the Association for Petroleum and Explosives Administration

Published by the Association for Petroleum and Explosives Administration

Contents

TALKING POINT

NOTES AND NEWS

NEW CONVEYANCE REGULATIONS

PIONEERS OF PETROL

LONDON NEWS

GAS FREEING TANKS P.T.F.E. TAPE

BRANCH MEETINGS

POLITICS OF HEALTH AND SAFETY NEW PRODUCTS

UNATTENDED SELF SERVICE INDEX

77 78 81 82 84 85 91 92 93 95 98 99

Opinions expressed in this Journal are not necessarily the views of the Association

...,

Talking Point

The Dangerous Substances (Conveyance by in Tankers and Tank Containers) Regulations 1981 come mto force on Jan 1st 1982 replacing the existing petroleum conveyance regulations.

The Association and many Local AuthontIes made theIr views clear on the error made by the HSC on enforcement of these Regs. But again the HSC have chosen to ignore this advice and we will see the Environmental Health Officer responsible for tankwagon inspection on fIlling stations.

The experience ofthe upper tier authority is to be lost and instead of a few Authorities there will now be many. I hope that no serious accident occurs through either lack of inspection or through inexperience. .' . .

The old saying is that The Law is an Ass:- m this case It IS the Law Maker-The HSC.

Honorary Secretary

Honorary Editor

notes and news

INCREASE IN UCENCE FEFS FOR STORING PETRoLEUM SPIRIT

The licence fees for storing petroleum spirit will be increased from January 1, 1982 under regulations laid before Parliament by Mr David Waddington QC, Under Secretary of State for Employment.

The fees which were last fIxed in 1978, will increase from £10 to £16 ;,er annum for up to 2,500 litres; from £15 to £24 for amounts between 2,500 litres and 50,000 litres; and from £30 to £48 for more than 50,000 litres. The cost of transferring a licence will also go up from £2 to £3.

The increased fees, which are necessary to meet the higher costs of licensing authorities, follow consultation with the local authorities, harbour authorities and other interested parties.

OIL STORAGE AND MOVEMENT OPERATOR AND DRIVER TRAINING GUIDELINES

The Petroleum Industry Training Board has just published the above guidelines. They state that with pending and proposed legislation laying greater emphasis on driver training with hazardous substances it gives a practical and flexible approach to driver training.

The publication is available from P.T.LB., KingfIsher House, Walton Street, Aylesbury, Bucks. price £6.50.

LEAKING AEROSOL CAUSES EXPLOSION

Liquid leaking from an aerosol container is believed to have been the cause of an explosion which badly damaged a house in Norwich.

When called by the police to investigate, the fIre service fIrst thought that a gas leakage from a water heater in a low level cupboard next to a sink unit might have been the cause, but examination by an Eastern Gas Board engineer quickly ruled out this theory. The fIre service offIcer then found a 400 ml aerosol container labelled "BIG D Air Freshener" which was leaking liquid from the base.

It was assumed the aerosol had leaked gas into cupboards, and the pilot light on the gas heater was the source of ignition for the explosion

The occupant confIrmed that the aerosol had been recently purchased. When the can was examined no gas was left in the container, although some of the liquid product was still leaking.

The name of the retailer was established and on checking the stock, although no leaking cans were found, the base of some of the cans showed signs of corrosion and the manager removed them from the shop.

Damage to the house was severe. Cupboard doors were blown off,. a plasterboard stud partition wall had been moved Inch, and the kitchen, lounge and first floor bedhad been badly damaged, with glass being h rown 20 feet Into the There were no injuries, but adl been In the kitchen at the time of the exp oSlon InJunes could have occurred.

The technical d' f fi d h lfector 0 the manufacturers has cont at propellant was either butane or a mixture of utane and ISO-butane, with an explosive range of I . 8 to 9 per cent. The have withdrawn the remaining stock from the retruler, and are carrying out further tests. The code on the aerosol indicated it was at least two years old.

New Members

Mr.

With many new members in the Association I have been asked to publish a list of Branch Secretaries whom members may contact if they wish to attend or be notifIed of branch meetings.

The Association welcomes the following new members.

Mr. L H. Nairne, Associate Member Gilbarco Ltd., Cleansing Service Group, Associate Member

J. L. Bell, New Member

Mr. A. J. Gilson, Associate Member Technical Manager, South Yorkshire County Fire Service, Associate Member Fire Service Headquarters, Furnival House,

Mr. G. A. Edney, Associate Member Project Manager, Fire & Safety, lan S. Wilson (Construction) Ltd., Associate Member

Mr. A. F. Levett, Member Trading Standards Department,

South Eastern Branch Mr. lim Cook, Trading Standards Department, Midlands Branch Mr. N. Fox, Trading Standards Department,

Should any members wish to contact the Association's secretary if they wish to start a branch in an area of the country not covered by the present branches, every assistance will be given.

The Council note that there are a large number of members in Northern Ireland who is felt may benefit from the formation of a branch.

ELECTRONIC WATCHES AND CALCULATORs

Following bans on the wearing of battery powered watches and the carrying of electronic calculators in hazardous areas by a number of organisations, it has been asked whether a similar policy should be adopted in respect of fire officers inspecting licensed explosive stores and areas where flammable/explosive atmospheres may be present etc. Following a series of tests on analogue watches with both tuning forks and stepper motors and digital watches of the liquid crystal display variety, the Health and Safety Executive have advised that such watches may be used without the need for certification. Nevertheless, on the principle that the avoidance of unnecessary use of electrical equipment in areas of hazard can only contribute to safety, it is considered that Chief Officers will wish their personnel to comply with any procedures laid down by individual establishments. Because of the variety both in design and power of electronic calculators, however, it is considered that these may not be used safely in hazardous areas unless this has been confirmed by an individual assessment.

PROTECTING UNDERGROUND PIPES

.)1-. A proven remedy for pipes that corrode underground is the subject of a new British Standard just published by BSI. Entitled BS 6076 Tubular po/yethylene film for use as protective sleeving for buried iron pipes and fittings it deals with a means of resisting the effects of corrosive soils on buried pipes and fittings manufactured from ductile iron and grey iron in accordance with BS 4772 and BS 4622 respectively.

Polyethylene fIlm has been used as an anti-corrosion medium in the United States since 1951 and, having proved successful, is now employed for this purpose throughout the world. The tubular fIlm is sleeved over the pipes and fittings immediately prior to laying and overlapped at the joints to provide a close fit along the pipeline.

BS 6076 specifies the composition and other properties of tubular polyethylene fIlm for this application and quotes the sleeving widths to be used, according to the nominal diameter of the pipe and the type of flexible joint required. The use of polyethylene protective sleeving is described in two related standards, namely BS 5493 and CP 2010 Part 3.

DETECTION OF COMBUSTIBLE GASES

BSI has published the first three parts of a new British Standard of major importance to maimfacturers and users of gas detection equipment, as well as architects, purchasing officers, safety organizations and anyone else having responsibilities associated with the presence of combustible gases in particular areas. The standard concerned is BS 6020 Instruments for the detection of combustible gases, which specifies requirements for the construction, testing, safety and performance of portable, transportable and fixed instruments intended for the detection of potentially explosive atmospheres.

This first issue comprises Part 1 General requirements and test methods, Part 2 Safety and performance requirementsfor Group I instruments reading up to 5 % methane in air, and Part 4 Performance requirements for Group Il instruments reading up to 100% lower explosive limit. Two further parts are in course of preparation, namely Part 3 Safety and performance requirements for Group I instruments reading up to 100% methane and Part 5 Performance requirements for Group Il instruments reading up to 100% gas.

BS 6020 covers the following areas of application:

(1) Mines susceptible to firedamp (Group I instruments)

(2) Other commercial and industrial applications (Group 11 instruments)

Note: The use of Group I instruments is not permitted in mines under the jurisdiction of HM Inspectorate of Mines and Quarries, without the prior approval of the inspectorate.

The new standard applies both to mains and batteryoperated equipment. It does not cover instruments of the laboratory or scientific type used only for analysis or measurement, instruments intended by manufacturer to detect toxic gases only, or those used solely for process control purposes.

During the preparation of BS 6020 full account has been taken of concurrent work on similar standards in other countries, especially Canada and the USA, intention of minimizing international trade barners ID respect of the instruments covered.

Annual Subscriptions

The treasurer has asked me to remind those members who have not payed their annual subscription for 1981 that they will no longer be recognised as members of the Association. Please forward all overdue subscriptions direct to the treasurer.

Association Tie

The Council of the Association is considering having an Association tie made for sale to members. The design would be the motif of the Association of red flames inside a white circle and the letters APEA. The tie would be of good quality and the design woven into the fabric.

Before the Council goes ahead with the order for the ties, would members who are interested please indicate to the Secretary"Mr. Brown (0480 57344) or through their Branch Secretaries.

Eastern Branch

Mr. B. Taylor, Trading Standards Department, Yorkshire Branch Mr. R. Kitching, Trading Standards Department,

LEGAL PROCEEDINGS

The following prosecutions taken by this authority may be of interest to members of the Association.

1. Two employees of an industrial premises received bums to both legs as a result of a fire started by smokers, materials. Proceedings were instituted against the company, as licensees, for the following offences under the Petroleum (Consolidation) Act 1928, being contravention of the conditions of licence:-

a) keeping petroleum-spirit outside the designated storage area;

b) failure to display a copy of the relevant licensing conditions;

c) failure to ensure that employees took all due precautions to prevent an accident by fire and explosion.

The case was heard at Watford magistrates court, where the company pleaded guilty and were fined for (a) £300, (b) £25, (c) £300 and ordered to pay £25 costs.

2. A routine inspection of a petrol filling station revealed contraventions of the licensing conditions for which the licensees had previously been warned both verbally and in writing. Proceedings were instituted against the company for the following offences under the Petroleum (Consolidation) Act 1928, being contraventions of the conditions of licence:-

a) fire equipment missing;

b) dip opening and off set fill pipe caps missing; c) failure to keep a copy of the licence on site; d) failure to number off set fill pipes.

The case was heard at St Albans magistrates court, where the company pleaded guilty and were fined for (a) £40, (b) £60, (c) £10, (d) £200 and ordered to pay £50 costs.

3. Being observed by a policeman to syphon petrol from a car tank into a plastic container, the driver of a vehicle was arrested and taken to a police station, where the vehicle was found to be carrying other containers of petroleum-spirit. The police informed the local officer, and as a result proceedings were Instituted against the driver. The offences were under both the Petroleum Spirit (Conveyance by Road) 1957 and the Petroleum Spirit (Motor Vehicles etc.) Regulations 1929 and related to:-

a) Conveying petroleum spirit in a container not being met::u and containing more than one pint;

b) petroleum spirit in a container not suitably Indicated "Petroleum-Spirit" "Highly Inflammable'"

c) having spirit in a container exceeding two gallons capacity' d) having petroleu ' '" . b . al m SPIrIt In a contaIner not eIng met The case Was h d defendant f '1 ear at Barnet magistrates court, where the that he ID ed to. turn up, having indicated by telephone absence pleadIng guilty. The case was heard in his prOved 'Th been adjourned previously, and found pay £40 co et flver was fined a total of £1 000 and ordered to s s.

NEW HM Ct.ny"

.I..I.u!'F INSPECfOR OF EXPLOSIVES

Mr. Phlhp Jone Executive's s IS t? be appointed as the Health and Safety from 1 Sept:: ChIef Inspector of Explosives, with effect t"" g er 1981. He replaces Mr Frank Ireland who IS re mn

Mr. Jones who will be based in Baynards House, Chepstow London, assumes responsibility for the work of the Explosives Inspectorate which covers the manufacture, storage and conveyance of explosives and other dangerous chemicals throughout the country.

FURTHER EXEMPTIONS UNDER EXPLOSIVES LEGISLATION

Two exemption certificates have been issued by the Health and Safety Executive (HSE) under the Explosives Act 1875 (Exemptions) Regulations 1979 allowing toy pist<?l caps or amorces and electric sparklers to be kept on open display for retail sales. They apply to England, Scotland and Wales and have been granted subject to certain conditions.

Toy Pistol Caps or Amorces

Up to eight dispensers of any toy pistol caps or amorces from anyone or more of all of the following groups may be kept on open display:-

(a) dispensers containing 450 or less rings with each ring having 24 or less toy pistol caps on it;

(b) dispensers containing 750 or less strips with each strip having 10 or less toy pistol caps on it;

(c) dispensers containing 150 or less rolls with each roll having 100 or less amorces on it.

Electric Sparklers

Up to 24 blister packs, each pack containing 20x 15 cm electric sparklers distributed by Pyranglo Limited may be kept on open display. This certi!1cate.ha:> for a period of six months only. Dunng thIS tIme It IS Intended to prepare a general any sparklers permitted to be sold In Great BntaIn to be kept on open display.

The two certificates have been granted fOllowing Consultation with interested bodies including local authority organisations and copies have been se?t to all county councils in England and Wales, all regional councils in Scotland and all London Boroughs. A copy may also be obtained from: HM Explosives Inspectorate, Baynards House, 1 Chepstow Place, London W2 4TF

While both exemptions are applicable to all retail or wholesale outlets for such fireworks and there is no need for individual establishments to make applications to HSE before taking advantage of them, the exemptions do not affect those legal requirements which require the registration of such establishments with the appropriate local authority under the provisions of Section 5 of the Explosives Act 1875 or the prohibition on the hawking of fireworks contained in Section 30 of the same Act.

PIPE LOCATING

There is a service available to provide accurate 1: 100 scale drawings of petrol filling stations with specific reference to underground services including petrol tanks, suction lines and vent pipes. Other services such as GPO cables, water and drainage systems can all be located and shown. The service could be most useful to site owners on redevelopment and I understand that the cost is quite realistic in comparison with unexpected expenditure due to accidental damage to services etc.

Further details from Pipe Locating and Tagging Services Ltd, 7 Farncombe Street, Farncombe, Godalming, Surrey. Telephone 0486829335.

The Dangerous Substances (Conveyance by Road in Road Tankers and Tank Containers) Regulations 1981

Revocation of Existing Regulations

These Regulations come into operation on 1 January 1982.

So far as road tankers and tank containers are concerned, they supersede:

The provisions of Sections 5 and 18 of the Petroleum (Consolidation) Act 1928;

The Hazardous Substances (Labelling of Road Tankers) Regulations 1978;

The Petroleum Spirit (Conveyance by Road) Regulations 1957;

The Carbon Disulphide (Conveyance by Road) Regulations 1958;

The Corrosive Substances (Conveyance by Road) Regulations 1971;

The Inflammable Liquids (Conveyance by Road) Regulations 1971;

The Inflammable Substances (Conveyance by Road) (Labelling) Regulations 1971;

The Organic Peroxides (Conveyance by Road) Regulations 1973;

The Petroleum (Consolidation) Act 1928 (Enforcement) Regulations 1979; and

The Petroleum (Consolidation) Act 1928 (Conveyance by Road Regulations Exemptions) Regulations 1980.

The. 1981 Regulations will apply, with a few minor exceptions, to the conveyance by road of dangerous substances (including petroleum spirit) in road tankers and tank containers. A tank container means a tank having a total capacity of more than three cubic metres (3,000 litres) other than the tank of a road tanker.

The Regulations impose duties on the operators of such road tankers and tank containers to ensure that the vehicles so used are fit for the purpose and that the tanks of road tankers and tank containers are regularly examined and tested.

The Regulations have the effect of preventing the conveyance of certain dangerous substances in road tankers or tank containers and require precautions to be taken against fire and explosion. They prohibit the overfilling of any tank which contains a dangerous substance and in certain cases require vehicles to be supervised when not being driven. They provide that an operator shall not convey a dangerous substance in a road tanker or tank container unless he has obtained information from the consignor to enable him to be aware of the risks created by that substance, that an operator shall ensure that the driver of a vehicle carrying a dangerous substance is given information to enable him to know the identity of the substance and its risks, and that the driver shall ensure that such information is kept in the cab of the vehicle.

The Regulations also provide that the operator of a vehicle used for the conveyance of a dangerous substance shall ensure that the driver has received adequate instruction and training.

Enforcement

The enforcing authority for the Regulations will be:(a) in a case where the vehicle is on a road or in some other public place, the Police; and (b) in any other case, the factory inspector or the environmental health officer (the authority being ascertained in accordance with the Health and Safety (Enforcing Authority) Regulations 1977) EXCEPT that (i) at any petroleum filling station and (ii) at any other premises licensed for the keeping of up to 100,000 litres of MOTOR SPIRIT in storage tanks the petroleum licensing authority will continue to be the enforcing authority for the purposes of Regulations No. 20.

Provisions Enforceable by Petroleum Inspectors

No. 20 of the 1981 Regulations requires that the provisions of Schedule 4 to the Regulations shall have effect for regulating the unloading of petroleum spirit at:-

(a) any petroleum filling station; and (b) any other premises licensed for the keeping of petroleum spirit which is intended to be used as fuel for motor vehicles, except where those premises are licensed for keeping more than 100,000 litres of such petroleum spirit in storage tanks.

So far as packaged goods (i.e., goods which are in road tankers or tank containers) are concerned, the varIOUS existing Regulations remain in force and continue be enforced as hitherto by the petroleum licensing authonty.

Schedule 4

The provisions of Schedule 4 can be regarded as being identical to those of No. 16 of the 1957 Regulations except that:-

(a) the Schedule relates only to the transfer of petroleum spirit intended to be used as fuel for vehicles from a carrying tank into a storage tank (I) at petroleum filling station or (ii) at any other premIses lincensed for the keeping of 100,000 litres or less of such petroleum spirit in storage tanks; and (b) paragraph No. 9 of the Schedule requires that, during the whole time of delivery from the road tanker, the tanker's engine and any other engine or motor which is attached to the road tanker shall not be run (c.f. No. 15(a) of the 1957 Regulations).

Delivery Certificates

Paragraph No. 12 of the Schedule permits continued use of the form of certificate set out in the 1957 Regulations as an alternative to the use of the new form specified in Part I I of the Schedule.

Carless Capel &Leonard Ltd.

- Pioneers of Petrol

John Butterfield, Director.

To research into the origins and history of Petrol as a motor fuel takes us into the early history of Carless Capel & Leonard , the earliest and longest lived present day independent U.K oil company. Carless was established in 1859 and from its origin to the present day the firm's production activities have centred on three main types of manufacture; Fuels , So lvents and C hem icals It is a curious fact that the ear liest activities were centred round the last of these and again today this is a field which is attracting the closest attention

Pe rkin 's discovery in 1856 of aniline dyes prompted the ori ginal partners to purify benzole so that it could be

nitrated and used to produce synthetic aniline dyes-a task requiring much care as at that time benzole could only be obtained in very small quantities from coal tar.

However, fuels soon came to take pride of place. In refining naphthas from the Scottish shale deposits fractional distillation was used to remove the lighter-boiling portions, which are so high inflammable, and the resultant oil found a ready market as a burning medium providing light and heat. At this time the disposal of the lighter portions from shale and from other oils must have presented a considerable problem which may well have been at least partially responsible for the development of cleaning processes for clothing and other fabrics for which these light fractions were well suited.

With the arrival of increasing quantities of the new American petroleum oils in the United Kingdom during the 1860's, Carless began to refine these also for lighting and

Carless 's Harwich refinery with Parkston Quay in the background.

·

heating. Here again the problem of disposal of the light spirits became acute. The sale of illuminating oils, containing such dangerous spirits, led to numerous accidents. Carless Capel & Leonard set their face against this unscrupulous practice and after considerable research were able to produce burning oils with a high flash point, acquiring a special reputation for their "Lighthouse" brand with its minimum flash point of 100° Fahr. Sir Boverton Redwood played a prominent part in advising the government of the day on preventative measures against the use of highly inflammable oils and in the introduction of the first Flash Point legislation. The resulting official apparatus, designed by Frederick Abel, for testing the flash point of spirits is basically that which is still prescribed under current petroleum legislation.

Alongside these developments in burning oils progress in the solvents field continued. Improvements in distillation techniques brought about the production of petroleum spirit fractions of carefully controlled qUality. Between 1880 and 1890 a process which made great progress was the extraction of fat required for the manufacture of soap. This process was later extended to cover margarine, and vegetable seeds were extracted in addition to animal bones and the other sources originally used. For all these purposes the petroleum spirit employed had to be as odourless as possible and entirely free of oily residue.

Another aspect of the trade in various illuminants and especially in gas merits some amplification. It became necessary from the seventies onwards to devise a method of measuring illuminating power. It was not easy to find suitable standards which could be reproduced accurately. Eventually a grade of Pentane was chosen. Its specification was exacting, but Carless Capel & Leonard were able to manufacture it, and it became the officially recognised fuel ror Standard Lamp. Thus started a long range, Issumg from the ongmal works at Hackney Wick, East London, of carefully manufactured petroleum ether fractions designed mainly for laboratory use.

The problem of the disposal of the more volatile fractions rrom distillation presented great difficulty to the mdustry and, m particular, occupied the attention of the partners. doubt they were pioneers in the pro?uction petroleum spirits of light gravity dUrIng the eIghtIes and their experience in this field was upon .when the internal combustion engine was first mtroduced mto the United Kingdom for installation in motor launches. At first owing to the primitive apparatus for carburation and ignition used in internal combustion engines, the emphasis was laid on volatility and the specific gravity test was the main criterion of quality. The "launch spirit'.' ' as it then called, that Carless Capel & Leonard supphed to SImms and other pioneers of what was to become the motor car engine, had a specific gravity of ·680. From 1890 to 1903 this was the firm's first "Petrol". Although it actually continued to be marketed till 1939 it was largely in 1903 by the Company's Standard WIth Its specific gravity of ·700 which was to be pre-emment the country for many years.

The advent of the mternal combustion engine was, of course, an event of world-wide social and economic importance. Simultaneously, however, it exerted a revolutionary effect within the petroleum industry because its more volatile products became a vital necessity instead of a disposal problem.

The compression ratios of the early engines were low and "aromatics", now widely recognised as a valuable component of motor fuels, were then anathema. In refining the fuels, therefore, the aim was to reduce aromatics to a minimum. By 1914, however, engine design had made such

strides that benzole had become recognised as a desirable constituent of motor fuel and during the 1914-18 war benzole mixture-that is to say, benzole mixed with petrol-was supplied in large quantities to the fighting services.

Between the two world wars the growth of popu1ar motoring and the mass production of cars led to a trend for increasing the compression ratio of engines in order to gain greater efficiency of fuel combustion and power. This trend has continued right up to the present day, marching together with improvements in the quality of fuels. In particu1ar the suppression of engine "knock" caused increasing research from the thirties onwards and among other work in this field Carless Capel & Leonard were one of the firms who played a leading part in blending tetra-ethyl-Iead, as an "antiknock" additive, into motor fuels.

These great chemical changes in the nature of motor fuel over the years were accompanied by improvements in the technique of refining. Other distillates in addition to motor fuels came to take their place in the Company's range of products. They included a substitute for turpentine which was found suitable for the paint industry. They also included an illuminant, specially treated to ensure freedom from residue, which had an exceptionally sweet odour. Under its registered name of "Lythene", it was used for many years as a fuel for lamps in lighthouses in many parts of the world and also, but at a later date, as a clean and quick drying solvent for certain surface coatings.

In 1964 the Company opened its new Refinery at Harwich at a time when the basic raw materials derived from Coal Tar Fractions were being displaced by changes in the technology of gas making as the I.C.I. steam reforming process using petroleum feedstocks took over from coal.

The new Refinery therefore established a new range of solvent products based on petroleum feedstocks which gradually took over from the coal based fractions. In 1968 another major development in the Company's history took place when the first gas condensate, liquid hydrocarbon derived from Natural Gas processing, was taken into the Harwich site for refining. This material gives rise to chemical feed stock naphtha, kerosine and Gas Oil and arises at Bacton in Norfolk from the three North Sea Natural Gas producing companies. It is transported in 500 tonne block trains from a pipeline served terminal at North Walsham to Harwich on a daily basis with peak arisings in the winter in line with the pattern of gas production.

The Harwich Refinery continues to make a range of specially tailored solvents for a wide range of industry, many of which are Petroleum Spirits by legal definition. Consequently the whole site is licensed Petroleum storage. Fuels particularly from Gas Condensate continue to be important although Motor Gasoline (Petrol) has not been manufactured for some years. A grade of lead free Petrol is however manufactured in small quantities for motor manufacturers' internal use and Carless has recently entered the Aviation Gasoline business, thus maintaining its link with its origins.

The Refinery at Harwich now consists of some 125,OOOm 3 of Petroleum Spirit storage in cone roofed and floating roof tankage and a processing capability of approximately 330,000 tonnes/year of mixed feedstocks. This now operates under the wholly owned subsidiary company Carless Solvents Ltd. Today the Company supplies, in addition to its traditional Fuel and Solvent products, feedstocks for the Chemical Industry, principally for cracking to Ethylene or reforming to make Benzene, Toluene and Xylene. It is continually looking for areas of manfacture which supplement the tonnage products and take advantage of its own county-wide distribution system.

Death by f"1re

While front of a car in a garage attached to a dwelling In Croydon was being raised, the rear of the vehicle slipped off the axle stands. As the vehicle fell one of the stands punctured the fuel tank and vapour from the resultant outflow of petrol was ignited by an L P G heater The man working on the car suffered severe died three days later.

The flre was exf . h d Ingllls ed by the Brigade; the garage roof was estroyed, the doors were burnt and the walls were cracked by heat.

A sticky end

in Hounslow and four flbre glass cars WI n It were destroyed b fi solvent fl y Ire when a tank of degreasmg solvent owed a man welding a chassis, and the were no Bngade extinguished the fire and there after the flre the remains of the cars could be scrape up WIth a shovel.

Garage-Workshop Fire

A man received mi b. extinguish a fIre· nor to hIS hands after attemptmg to being repai d m a car m a small workshop. The car was pipe. After one of its defects was a leaking petrol unprotected t e Ire, a damaged hand-inspection light of the Alth hype was found nearby oug nothing Id b . petrol from the I .cou. e proved it was suspected that tected tungst pIpe had dripped onto the unprofilament. en ulb, broken it and ignited on the hot

The car was co I I damaged Th f mp ete Ygutted and two others were badly . e Ire was extinguished by the Brigade.

Not all balls

Fire broke out operative p m a ball mill in a paint factory when an point of 89 a ?ydrocarbon solvent, having a flash b ,Ihnto It. He was slightly injured; the fire was Th. Y t e Works fire team e CIrCumstanc f those When fi b es 0 the mCIdent were very SImIlar to occasions in out in the same mill on two previous instructions h d and 1978. The operative, contrary to pouring but'th a n?t earthed the vessel from which he was incident Was petroleum inspector investigating the was impressed b satIsfled that this was the whole story. He inside the vessel i;he statement that ignition had occurred objects among th suspected that unearthed foreign metal static accumulat e msulated balls of the mill were acting as to be removed he arranged for the balls metal objects indud SIfted. consequent haul of foreign of which Would h ed a dram key and four metal bungs any consequence the ave been an efficient static accumulator. In out similar no persuading to carry the premises. WIth SImIlar results on other ball mills at

Solid-filled tank fi A . Ire smgle-storey . petrol filling st:;tensIon of a sales building at the rear of a petrol tank .encroached on a 6000 gallon disused 1974 with a 1 in 10 WI!h five others, had been solid-filled in The bUilding mIX of concrete. 1 m x I m) to be surveyor asked for a section (about accommodate a from the top of the tank to tank had been beam, despite the fact that the thICkness ed In concrete over 300 mm in

The builder, acting on the advice of the petroleum inspector, drilled holes in the appropriate section of the tank and injected water before cutting. However, when cutting began there was a hiss within the tank and a brief jet of flame appeared from one of the holes previously drilled. Work proceeded very cautiously after that, and without further incident.

Later examination showed that at the extreme end of the tank (3.3 m from the manhole) there was a 200 mm space between the top of the tank and the concrete infill, and this space narrowed to 50 mm at a point 1.5 m from the tank end.

Rioters

During the course of a recent riot a gang of youths invaded the forecourt of a petrol filling station in Lambeth. Postpayment self-service equipment is provided at the premises. When the attendant saw what was happening he wisely locked himself in a room at the rear of the building. The windows of the building were smashed, as were the glass doors, when the mob threw sand buckets at them. The loudspeaker system was also damaged.

A youth was seen to take a pump nozzle and attempt to discharge petrol on to the forecourt. Fortunately the pump was not energised and only a small quantity of spirit was spilled. This was promptly ignited by the youth who then dangled the nozzle in the flames and damaged the plastic nozzle shroud.

By the time the Brigade was able to get to the scene the fire had gone out, all spilled petrol having been burnt up. There were no casualties.

Plumber for pump

A small spillage of petrol occurred when a petrol pump was knocked over at a Croydon filling station. The Brigade was summoned and the spillage was sanded down. The filling station proprietor to call in plumber to effect repairs but had to make do m the end WIth Pump Maintenance!

LEGAL PROCEEDINGS

Infringement of licence conditions

A motor company was fined £1,000 with £130 costs at Highgate Magistrates Court on 27.4.81 for contravening licensing conditions in that it kept some 35 gallons of petroleum spirit in unauthorised locations dangerously near hazardous electrical equipment and had no hand fireextinguishers nearby.

Infringement of the Petroleum Spirit (Conveyance by Road) Regulations 1957

A tank wagon driver was fined £75 with £25 costs at Croydon Magistrates Court on 18.5.81 for infringing Regulation No. 16 and causing a spillage of petrol.

Down Rover

Having purchased some petrol for her automatic Rover car at a petrol filling station in Merton, a woman driver operated the ignition key of the vehicle. The gear selector must have been in "DRIVE" because as soon as the key was turned the car leapt from its position by a pump into the front of the shop. A wall protecting a staircase at the rear finally stopped the car. Neither the console operator nor the driver of the car was hurt although it is extremely likely that they both got the shock of their lives! These two people evacuated the shop via an escape door at the rear of the building.

The Evaluation of an Improved Method of Gas-Freeing an Aviation Fuel Storage Tank

P. J. FARDELL- Fire Research Station, Borehamwood, Herts. (Gt. Britain) and B. W. HOUGHTON, Department of the Environment, Property Service Agency, Directorate of Engineering Services Development, Croydon, Surrey (Gt. Britain) (Received July 19, 1976)

Summary

A new technique is described for the gas-freeing of large storage tanks used for aviation fuel. The technique involves the use of natural and mechanical ventilation, together with an air-driven pump for removal of liquid residues from the irregular bottom of the tank. As assessment was made by gas-freeing a 4500 m 3 (1 M gal) tank in which the atmosphere was monitored using portable flammable gas detectors and checked by the analysis of samples using chromatography. The new technique was much quicker than the traditional method of gas-freeing and was more controlled so that a work schedule could be devised in advance with confidence.

The portable gas detectors were shown to under-estimate gas concentrations; it is thus imperative that the concentration levels at which various inspection and maintenance operations are permitted in tanks should reflect the likely errors of the instrument used to measure concentrations.

Introduction

Aviation fuels are customarily stored in relatively large either above or below ground, and it is necessary to empty the tanks for inspection and purposes. The usual interval between inspectIOns IS 1 year for tanks which are not epoxy-lined and at less frequent intervals for those which are epoxy-lined. The epoxy-lined tanks are relatively modern, with conical bot.toms and centre sumps to avoid fuel puddling problems whIch can Occur with 'flat' bottomed tanks which have welded joints. There are a considerable number of tanks in use are not epoxy-lined, and these older tanks present conSIderable difficulties in gas-freeing. Problems arise because the tanks which do not have conical bottoms, may ?e constructed with lap joints, and the bottom may be Irregular, causing pockets of fuel to collect in the low spots, which cannot be removed by the sump pump.

Before any maintenance can be started, all traces of fuel must be removed. Traditionally, the method of doing this has been first of all to ventilate the tank until the measured concentration of the fuel was less than 50 per cent of the lower explosible limit (I.e.I.). The removal of the flammable vapour was carried out by removing the manhole covers from the tank and allowing natural ventilation, sometimes assisted by air movers, to cause the fuel concentration to decrease to the accepted level. The next step was for an operator to enter the tank, wearing full protective clothing and apparatus, to inspect the tank and to ascertam the quantity of remaining fuel to be removed. After the inspection, operators entered the tank and commenced to sweep the remaining liquid fuel either towards the sump or to adjacent low spots which may have after the tank had been constructed. By this actIOn, further vapours were generated which could raise the concentration in the atmosphere to above 50 per cent I.e.l. and the operators then had to withdraw pending further ventilation.

This cyclical procedure led to protracted and uneconomic working, but was essential on safety grounds. When all the liquid had been swept up and the tank was freed from all remaining liquid fuel, sludge, scale, and other arisings, and the gas concentration reduced by ventilation to an acceptable level, the next stage of the maintenance could proceed.

The traditional procedure had the disadvantages of being time-consuming, expensive, with prolonged hazardous conditions, and the duration of the work could not be predicted accurately. An improved method was therefore sought, particularly to obtain greater safety, and more rapid and controlled operations.

An opportunity arose to develop a new procedure for the gas-freeing of a large aviation fuel tank in the U.K., used for the storage of JP-4 aviation fuel; the tank was mounded over so that limited access was only possible from the top. Measurements were made of gas concentrations both by the use of portable gas detectors and by sampling for laboratory analysis, in order to determine what changes took place during the operations.

Description of tank

The tank, shown diagrammatically in Fig. 1, was 32 m in diameter and 5.6 m high (from the tank bottom to the underside of the roof). It was constructed of steel with reinforced concrete protection external to the shell and roof. The roof was supported by columns at 3.3 m centres and the tank was further protected by an earth covering. The capacity of the tank was 4500 m 3 (l M gal nominal). The lap welded tank bottom was undulating, and pockets of fuel collected in the low spots. The fuel in the low spots could not be withdrawn by the sump pump. The pumping equipment was located on the top of the tank. There were two top access manholes of 0.76 m diameter, and a larger access 1.37 m X 1.22 m to the floating suction head used in the operation of the tank. The tank was of the conventional protected type and difficult of the very limited access and pOSSIbIlItIes for ventIlatIOn.

Objectives of exercise

1. To obtain realistic and factual information in collaboration with DOE/PSA on gas concentrations in the tank during the period of gas-freeing.

2. To determine the time required to reach a25 percent l.e.1. reading at the bottom of the tank.

3. To determine the gas concentrations in the tank surrounding the operators during the sweeping up of the pools of fuel.

4. To estimate the quantity of fuel remaining in low spots, after the main pumping operations, and the area and location of the pockets of fuel.

5. To determine the efficiency and effectiveness of the plant and equipment employed for the gas-freeing operation.

6. To compare the readings obtained with portable detector for flammable gases with laboratory analyses of gas samples taken simultaneously in the tank.

Manhole No 2

Roof supported by RSJ columns at 3·264m crs

No 1 manhole 076m dia Access No 3 1·22m x 1·37m

Key plan of tank No 2 manhole O·76m dia Earth cover

Tank surrounded by reinforced concrete Steel tank

Equipment and apparatus

Two compressed air operated venturi type air movers were used 15 cm diameter, overall length 1.2 m and weighing 14 kg. They induced air through the tank at a rate of 35 m 3 /min (1200 ft 3 /min). Figure 2 shows one of these in position. Canvas wind sails were also used for ventilation purposes, one as a scoop to deflect the air into the tank (Fig. 3) and the other as an educator tube with three side flutes (Fig.4). The tube was 0.75 mindiameter, which fitted into the manhole and extended to within 0.9 m of the tank bottom. Residual liquid fuel was removed using a compressed-air operated portable pump of capacity (300 IImin) at 7.6 m suction lift. The weight of the pump was 35 kg, the overall dimensions were height 0.45 m, length 0.56 m, width 0.42 m, permitting it to be lowered through the standard-sized manholes. The suction and deliveTY. for the pump were of anti-static rubber, 50 mm m diameter, suitably bonded and earthed (Fig. 5). A diesel driven portable air compressor at 700 kN/m2 (7 bar) the venturi air movers, the portable pump, and the breathmg apparatus used by operators within the tank. The at':ll0sphere inside the tank was tested for flammable gas, usmg three models of portable detectors (signed A, Band C)'. Types A and B were manually aspirated, and were call.brated for pentane. Type A is shown in Fig. 6, and was for use with leaded fuels. Type C was nonaspirated and was calibrated by the manufacturers to at 50 per cent l.e.l. with JP-4, and gave both audible and ViSUal alarms (Fig. 7).

A w.as provided with an 8 m long neoprene samp mg me which contained a T-piece enabling gases to be sampled subsequent analysis. Figure 6 shows the method of The samples were taken and stored in a 1 ml synnge, the needle of which was capped with a silIcone rubber disc. All samples were analysed using a gas fitted with a dual flame ionization detector, WIth automatic integrating facilities.

Diary of events

Tuesday, 1 July 1975

At 15.40 hours the two 0.76 m diameter manhole covers were removed. The readings of portable gas detectors A and B, were off the scale. These observations were taken just

inside the tank. Five further observations using the portable detectors were taken during the afternoon, which were again off the scale of the instruments. The wind sails were placed in position at 16.10 and then left overnight. The wind and weather condItIOns throughout the exercise are shown in Appendix A.

Wednesday, 2 July 1975

At 08.30 hours the portable detector readings were still off the scale but the meters reacted less vigorously. The air movers were then installed in place of the wind sails. One air mover was blowing into the tank and the other ejecting.

At 11.00 hours the access cover (no. 3) over the floating suction head was removed and quantities of fuel were observed directly below. A suction pipe was lowered to the tank bottom and the air operated pump connected to the compressed air supply. The delivery pipe was taken to the interceptor pit adjacent to the tank and the fuel was later transferred to a bulk lorry. The pump was removing 90-120 I of fuel per minute with no difficulty, against the suction lift of about 7.6 m. Approximately 14 m 3 of fuel not removable by the sump pump were removed with the compressed-air pump located at the top of the tank. Four gas concentrations readings were taken during the day, again indicating over 100 per cent of Le.!. At 16.45 hours the wind sails were again erected, the scoop sail at manhole 2, and the educator sail at access 3.

Thursday, 3 July 1975

A gas sample and portable detector readings were taken at 08.55 hours 1.9 m below the roof at manhole 1. A summary of the gas sampling and analysis data appears in Table 1. The portable detectors A and Bread 30 per cent I.e.1. A second reading was taken at 4.3 m from the top of the tank, the reading, however, was off scale. At 10.25 hours, 1.8 m below the roof, a reading of 70 per cent l.e.1. was observed; at this time the air movers were operating with 1 blowing and 1 ejecting, and were obviously disturbing the concentrations at the bottom of the tank.

At 10.50 hours a reading of 66 per cent l.e.I. was observed at 4.3 m below the roof. A further sample for chromatographic analysis was also taken.

Fig. 4. Wind sail eductor tube.

At 12.00 hours another reading was taken at 4.3 m and 4.9 per cent l.e.1. A further gas sample was also taken. At flls .tIme the air ejector was fitted with a 15 mm diameter b eXlble suction hose, extending to within 0.60 m of the tank ottom op . At ' eratmg at access 3. 114 .45 hours the portable detector reading was 7.5 per at a depth of 4.3 m; at this time portable detector th owe red to the tank bottom and 'alarmed', indicating tel: e .1. was above 50 per cent. The wind sails e left m positIOn overnight.

Friday, 4 July 1975

on portable detector A were taken at 08 55 hours were to pe t I I At 09 50h r cen .e , 4 m down. read' ours, at 1.8 m from the room at manhole I, the mg was 9 per cent I e I At to 0 and a f ' the reading had risen to 19 per cent I.e.!. taken Iler sample for chr?matographic analysis was had . .05 hours the readmg of the portable detector this per cent l.e 1. 1.8 m down The reason for vanat lOn m gas concentration was that the air movers

Fig. 3. Wind sail air scoop.

Fig.

TABLEt

At 11. SO hours the operators in the tank reported readings of 6 per cent on detector B, and detector C and not alarmed.

At 12.0S hours a further gas sample was taken.

At 14.1S hours, 2 operators re-entered the tank and commenced sweeping the pools of liquid fuel towards the sump. the same time a further gas sample was taken Apprmomately 1.4 m 3 of fuel were withdrawn from the tank by the compressed air driven pump still located at the tank top. The final gas samples were taken at 14.4S hours.

At IS 30. hours, at manhole 1, a reading of 12 per cent I.e.I. was gIven by portable detector A, sampling at 1.8 m below the roof. At 4.3 m below the roof the reading was 14 per The wind sails were left in position until the morrung of Monday, 7 July .

Monday, 7 July 1975

hours at manhole 1, 1.8 and 4.3 m down, the mg of detector A was 4 per cent I.e.I., but small pools of fuel stIll remained in the tank

At 11.IS hours the operators the tank and the driven pump was lowered into the tank do m. readmg of 14 per cent I.e.I. was observed 4.3 m wn, usmg the portable detector A.

At 11.30 ho . nea th b urs , at manhole 2, the readmg was 9 per cent r e ottom of the tank

At 12.IOh h re rt ours t e operators emerged from the tank and at all positions within the tank, readings of P rt e etector B were 4 per cent I.e I. o able detector C gave no response. t SObme fuel remained at the tank periphery and amounted o a out 140 I.

A t th is stage 't d 'd I was eCI ed to cease f urther operations on s ite untIl mod'f' I IcatlOns were made to the suction pipe for the air driven pump, to enable the small quantity of re maInIng fu It b d'" b e 0 e remove . A fIsh-tail suctIOn scoop was s u seq uently fabricated , incorporating a non-return valve °hn a wheeled frame and was attached to the suction pipe t e as shown in F ig . 8 . This has proved to be the most e ffe c tl ve In removing all the remaining unpumpable residue.

Analysis of samples by gas chromatography

1. Method

All samples were analysed using a gas chromatograph, fitted with a dual flame ionization detector. The column used was of stainless steel I.S m long, 2.1 mm i.d. packed with 'Porapak Q', with helium carrier gas. Each analysis was temperature programmed at 4 ° per minute from 30°C to 200°C An injected volume of O S rnl was used throughout. The total area of peaks for each sample was measured using an electronic integrator. The date and time at which the analysis was carried out was noted.

The chromatograph was calibrated using samples from an apparatus designed to generate standard vapour/air mixtures for measuring the I.e.I. of a vapour. This apparatus is described elsewhere [1]. The vapour samples slowly decayed when stored in the plastics syringes, and a number of samples of a vapour/air mixture, within the range of concentrations being considered, were taken and analysed several hours after collection could be corrected.

The steps involved in arriving at the vapour concentration were:-

(a) Run the sample and obtain the total area of the chromatogram.

(b) Calculate the delay between collection of the sample and its analysis.

(c) Correct the chromatogram area for the delay.

(d) Determine the vapour concentration from the corrected chromatogram areas and the calibration data.

2. Results

Eight useful chromatograms were obtained. The results are summarised in Table I.

The comparison between the readings of portable detector 'a', and the gas concentrations as obtained by chromatography is shown in Fig. 9. The detector tended to underestimate the true concentration as indicated in Fig 9.

The gas concentrations measured at 2 levels in the tank (4.3 and 1.8 m from the top) during the gas-freeing period , are plotted against time in Fig. 10 Details are also included of the times of major disturbances to the tank atmosphere due to the gas-freeing activity

Fig. 6. Portable detector 'A' showing sampling method.

Discussion

From the diary of events, and Fig. 10, it may be seen that the gas concentrations within the tank were brought down to ?elow 25 per cent I.e.I. within 2 days. This is a great Improvement over the traditional method and was due largely to the use of the compressed-air-driven pump to remove residual fuel and to the employment of the air movers and the wind sails. The reduction in surface area of liquid fuel, and the considerable ventilation of the tank atmosphere combined to reduce gas concentration rapidly.

The new technique completed gas-freeing in a much shorter period than the traditional method, with consequent economics in manpower. It will enable work to be planned in a controlled way, and a work schedule to be advIsed in advance, with confidence.

A considerable improvement in safety is obtained because the concentration of the atmosphere within the tank is between the lower and upper explosible limits for a much shorter time than in the traditional method. In addition, most of the residual fuel can be withdrawn before operators enter the tank for inspection and for final clearing of the Because a considerable proportion of the residual IS. removed mechanically by pumping, hazard is mlrumls.ed; with the attendant savings.

No dIffIculty was encountered in reducing the vapour concentration in the atmosphere of the tank to below 25 per cent l.e.l: and thus, even if the portable gas detectors have a substantIal error, the atmosphere is soon likely to be within accept d r' . e Imlts for Inspection and subsequent operations. tests showed that it was easy to reduce the gas concentratl?n to 4 per cent of the I.e I. and that it was readily possIble to monitor the decreasing concentration down to

this level, providing confidence as to the state of the atmosphere within the tank as the gas-freeing proceeded.

Some operators have used water as a means of flotation for removing residual fuel from the tank, but this method requires the provision of interceptors, and brings in the possibility of water pollution problems. The new method avoids the generation of large volumes of contaminated water / fuel and the associated problems of their segregation and disposal. The necessary equipment for the new method is readily portable and is easily manoeuvred on site. In particular, the air-operated pump can be lowered through the standard 0.76 m diameter manhole without difficulty.

Comparison of the readings of the portable detector A with independent gas analysis in the laboratory confirmed that the reading of the detector was consistently low, by about I I per cent. This means that the instruments underestimate the concentration of vapour being sampled. It is therefore important that the gas concentration level s at which various operations are permitted in tanks should take into account the likely errors of the instrument used to measure concentration in actual installations Part of the present exercise was to ascertain the time taken to achieve 25 per cent 1.3.1., and this level is marked as a hor izo ntal line on Fig. 10. The figure of 25 per cent l.e.1. has now been adopted by various authorities as the maximum permitted before entry to a tank for inspection can take place.

It is important that where the new technique is to be us ed adequate p:e-planning takes place to ensure that the prope; procedure IS followed and that all legal requirements are met: It is essential to necessary equipment act uall y on sIte be fore an operatIon IS started and that staff should be thoroughly trained in the use of the equipment.

Fig. 8. The 'fish-tail' suction scoop.

Fig. 9. Comparison of readings obtained with detector A and gas chromatography.

APPENDIX A Weather conditions during tests.

Date 117175 217175 3/7/75 4/7/75 717175

Time 15.58 8.55 10.15 16.30 8.55 10.25 10.50 12.10 16.45 8.55 9.50 10.50 11.30 12.05 14.10 15.30 8.55 9.30

Temp. (0C) 23 17 19 23 17 21 22 23 22 18 19 20 20 20 21 20 18 19

Windspeed (knots) 5 0 2 4 2 5 10 9 9 8 10 13 13 13 10 12 10 12

night 3/7/75 Direction Dew point (0C) N 7 N 8 SW 8 SE 8 NE 9 E 8 E 8 ESE 9 E 8 NE 12 NNE 12 NE 12 NE 12 NE 12 NE 10 NE 10 ENE 11 SW 13

THE RECOGNmON AND REDUCTION OF IGNITION HAZARDS IN THE CHEMICAL

INDUSTRY-an Oyez mc conference on 12th November 1981 at the Regent Centre Hotel, London Wl Safety in the chemical industry is becoming an increasingly integral part of efficient managem.ent an of the hazards involved when dealmg WIth chermcals should promote more positive !hinking along.safety lines. This oneday conference will dISCUSS the varIOUS types of hazard found in the chemical industry, the associated risks, the sources of the hazard, the practical guidelines and protective measures that need to be taken to ensure a safe environment for both workers and the community alike.

It will discuss firstly fire hazards in chemical plants due, for example, to the storage of flammable chemicals the sources of ignition and the fire control systems of procedures required. Another topic will be electrical installations and the equipment that acts as a source of ignition and their relation to vapours, gases and powders: Conditions for runaway chemical reactions will be reviewed and methods for avoidance against such reactions Chemical plant operations will ?e looked at, hazards from the storage of t,natenals, grinding and milling powders, and drying operatIOns; together with SOurces of hazards static electricity, and thermal decomposItIOn of powders. A study WIll be given of th hazards associated with organic peroxides, how to these the proced.ures safe and transport of this partIcular chemIcal. Fmally the VIews of the Factor Inspectorate will be put forward with information on thY laws concerning chemical hazards and how to apply

Acknowledgement

This paper' C d b '. IS rown copyright and is reproduce Y of the C0!1t:oller, H.M. Stationery is R h by pernusslOn of the Director of the BUlldmg esearc EstabI' h . . h Joint F' R IS ment. (The Fire Research StatIon IS t e E Ire esearch Organisation of the Department of the nVlronment a d th n e FIre Offices' Committee.)

Reference

I P J. Fardell Th 'th (' f ' e performance of some portable gas detectors WI aVla Ion uel vapo 1 T t with I urs at elevated temperatures. Part es s n-hexane. Avtag' d 'C' h S' Fire , an Ivgas' vapours Fire Researc talIOn, Research Note 938, Borehamwood, 1972.'

This conference aims to bring together a broad range of bodies and disciplines associated with the problem of chemical hazards and will be of particular use to plant managers, safety officers engineers, safety advisors, hazard analysts, occupatIOnal personnel managers, planners, emergency servICes, scientists and environmentalists.

The meetings will take place on Thursday, 12th November at the Regent Centre Hotel, London WI. The fee will be £100:00 plus VAT to include all technical sessions, do.cum:ntatlOn: luncheon. Enquiries to: MISS FlOna Spmdlove, SCIentifIc and Technical studies, Oyez IBC Ltd., Norwich House, Norwich Street, London EC4A lAB. Tel: 01-2422481.

PTFE Thread Seal Tape

by K. J. Taylor - TBA Industrial Products Ltd.

The Material

PTFE is the recognised and recommended abbreviation for polytetrafluoroethylene, (CF2)n in chemical notation. It is a plastic in relatively common general use but, unlike many, it IS less well recognised under its chemical name than under one of the various trade names e.g. Fluon, Teflon, Soreflon, Hostaflon, Algoflon.

Discovered in 1938 and with the first pilot plants built during World War 11, PTFE was first produced commercially in 1946 although the scale remained small until about 1950. Today the production rate of this exceptional engineering material is over 20,000 tonnes per annum, with over 50/0 and perhaps as much as 10% of the output being converted to tape for the sealing of threaded joints.

PTFE has an outstanding combination of properties, of which its virtually total chemical inertness, excellent electrical properties, Iow coefficient of friction and the retention of these over a wide temperature range are probably those which are most exploited. The claim that PTFE is completely inert chemically is often made but is not literally correct. However it is attacked only by such highly aggressive chemicals as the molten alkali metals e.g. sodium or potassium or (slowly) by fluorine gas so that for all practical purposes the claim may be accepted. Equally important, no chemical is known which will dissolve, or even swell, PTFE over its operating temperature range, which extends to 250 D C (480 D F). This makes it the ideal material for use in the petroleum and chemical industries.

The Product

More accurately the heading should be plural, since a number of different qualities of thread seal tape are currently available. The choice of which grade to use in a particular application may not be immediately obvious but is in fact relatively simple and for this purpose it is instructive to consider the background to the establishment of the present range both from a technical and historical viewpoint.

Thread Seal Tape of the highest quality is 99.95% PTFE. The 0.05% remainder comprises a residue of the lubricant which is used during the tape production and/or the solvent, which in some processes is used to "degrease" the tape.

The present British Standard, BS.4375: 1968, allows the residual lubricant content to be as high as 1% and this composition is adequate for very many purposes. However, for certain critical applications, most particularly where high oxygen concentrations are present, or perhaps where there is contact with potable water, lubricant levels below 0.1 % are essential.

Density

Whatever the lubricant content, PTFE tape can be produced to have a bulk density anywhere in the range 0.3 1.5. Originally all tapes had the maximum density of 1.5 but, as soon as the first lower-density tapes became available, these rapidly predominated. These products were found to be equally effective sealants, to be easier to wrap and less costly to produce. By today's standards they are of medium density i.e. generally in the range 0.8 1.2.

In turn the medium density tapes have lost ground to the low density versions, which most usually are manufactured to be in the 0.4 0.6 range. The major factor in this change

is that of cost reduction. Although there is some further technical gain in that these tapes are preferred for narrow bore pipes and/or fine threads, they perform less well in heavy duty work. But they remain easy to wrap and, crucially, they still perform well in the overwhelming majority of applications at a lower price.

Thickness and mass/unit area

Almost all tape sold in the U.K. at the present time is 0.075 mm (0.003") thick. In some countries 0.1 mm has been officially specified for some time for use on gas lines and, for more demanding applications, the use of even thicker tapes is becoming necessary. Conversely, in the continuing drive for economy, thinner tapes are beginning to appear in many countries abroad. It is pertinent to consider these developments in more detail, particularly with regard to the quantity of tape to be used.

An essential feature with any joint sealant is that the correct quantity ("not too little, not too much") should be applied. Where pastes are used this quantity is traditionally achieved by using too much and wiping off the excess, which is squeezed on to the outside of the pipe. The excess, which is squeezed simultaneously into the pipe and hence into its contents, is ignored. This is messy and wasteful at the very least. More seriously, if a packing such as hemp is used as a secondary agent to provide bulk, the packing/paste ratio may vary between relatively wide limits to the detriment of performance.

A strong advantage of PTFE tape has been that a controlled quantity is simply and regularly applied. It has been a feature further to the advantage of low density tapes that a single wrap provides a small but often adequate quantity of sealant; and, if more tape is required, multiple wrapping is a simple procedure for increasing the dose in small increments.

As already noted, almost all the tapes available in the U.K. are 0.075 mm thick. However, if a range of thicknesses becomes available it becomes apparent that one aspect of simplicity is at risk. Confusion in this area needs to be avoided and fortunately this is easily achieved by considering neither density nor thickness alone by combining these two in the much more meanmgful parameter of mass/unit area: this the majority of tapes currently avaIlable m the U.K. fall mto the ranges 30-45 (95%) and 110-115 (5%).

Interestingly, at least some of the thmner tapes aVaIlable abroad are being manufactured at densities which bring them into the 30-45 band, which suggests this may represent the optimum in economy/performance. At the other end of the scale, it is already clear that to meet the most stringent requirements (see next section) tapes in the region of 200 g/m2 are required.

Specifications

All tapes of U.K. manufacture and some imported tapes conform to BS.4375:1968. This standard is adequate for all general plumbing applications and also for higher pressure work with certain limits.

For work with gas, the standard set down in British Gas publication IM/16 is more appropriate and is satisfactory for pipe diameters up to at least 50 mm (2") although tape to

BS.4375 is allowed on some installations up to 15 mm at the moment.

Where tape is to be used in the presence of high concentrations of oxygen, it is essential that the residual lubricant content is below the safe working limit. At present the standards for this are set by the major oxygen suppliers and are met by all the V.K. producers of tape. The tape manufacturers are actively collaborating to achieve a new and published standard, which will include a safe limit automatically. It must be emphasised that compliance with BS.4375 in its present form is not sufficient.

No standards directly related to LPG have been set down but appropriate tests do exist within BS.5292:1980 and are thus incorporated automatically into the IM/16 standard.

Summary

PTFE tape is used extensively and increasingly for sealing threaded joints because:it is universally applicable (all pipe materials and virtually all fluids); Jomts are ready for immediate use' are easily dismantled after use; It does not contaminate the pipe contents;

it is clean and simple to apply; it operates over a wide temperature (at least 20°C to 250°C).

On an international basis, variety of standards (or lack of them) could lead to confusion but within the V.K. the position is relatively simple and promises to become even more so. At present the basic questions and answers are:-

1. Is the tape to be used in the presence of oxygen? If so, check that the quality (i.e. lubricant content) is satisfactory.

2. Is the tape to be used on large pipes and/or with gas and/or at high pressures and/or extremes of temperature cycling? If so, tape to IM/16 is to be preferred.

3. Is economy the primary consideration? If so, tape to BS.4375 will be satisfactory for most domestic and light duty industrial work. If in doubt check with your supplier*

* TBA Industrial Products. also. will always be pleased to advise.

SEALING MATERIALS DIVISION. PO BOX 40, ROCHDALE OLl2 7EQ. Telephone: (0706) 47422.

Welcome

A warm welcome was extended by the chairman Mr. R. J. Smith to the 32 members and visitors present as he opened the meeting at 11.00 a. m. A particular welcome was given to newcomers including Mr. K. T. MettamofSouth Yorkshire County Council, Mr. P. Clarke of Humberside County Council, Mr. E. Cowie of North Yorkshire and representatives of Fibresec Marketing Ltd. Mr. J. Pardoe and Mr. M. Jennings.

Minutes

The minutes of the Annual General Meeting held on the 17th April 1980 and the Additional Meeting held on the 10th 1980 were read and accepted as a true record. Proposed y B. Slater. Seconded by F. Minns.

Matters AriSing

The h' C c airman reported that the National Seminar on of Hazardous Substances in June 1980 at the H Ire all, Cambridge had been a full and very useful day. he. expressed dismay regarding forthcoming ",:,hlch affected functions which had traditionally be " m;lstered by Local Authorities, and which were to Ex pat·sse over" to the Police and the Health and Safety ecu IVe He f It h I was t b . e t at a ot of knowledge and experience and that representations on behalf of Local y nforcement Staff should be made.

Static Electricity

Mr. E. W Dea out on f1' n reported back on the tests he had carried informed regarding static build-up on hoses. He on flexible i that there appeared to be a problem p p at depots and the contact through hoses was nor as good as he had expected

L.P.G.

Concern was by the about the increase in portable L.P.G. contamers at retail level which were being stored and retailed without any statutory control.

Apologies

Apologies were received from 7 members.

Treasurer's Report

The Treasurer reported the bank balance as being £21.80p.

Any Other Business

Brian Slater informed the meeting of an Instant PreFabricated DERV Installation now available. It was completely portable, self-contained and did not require planning permission.

Representatives of Fibresec Marketing Ltd. gave a demonstration of a glass reinforced plastic liner for petrol tank access chambers.

Mr. E. Furniss outlined the requirements of recent legislation covering Explosives and the Conveyance of Petroleum in that the Health and Safety Executive had now been given the power to vary the requirements.

SUbject Matter & Venue

Various suggestions were made, the matter being left in the hands of the Secretary.

Termination of Meeting

The business meeting concluded at 12.40, the afternoon session took the form of a talk/demonstration by Mr. Gussman, Deputy Group Chief Inspector of Airports for Shell V.K. Oil, which was found to be extremely interesting and generated a great deal of discussion.

Vote of thanks given by B. Slater.

The meeting concluded at 4.00 p.m.

Minutes of the Yorkshire and Humberside Branch of the Association for Petroleum and Explosives Administration held on the 13th November 1980 at the Red Hart, Blyth, Nottinghamshire

Decision-making by 'Experts' alone not enough in Health and Safety Matters, says HSE Director

Decision-making on health and safety issues should not be taken by the 'experts' alone. In one way or another the people involved in the operation, those who bear the risks and share the benefits, must also be involved, said Mr. John Locke, Director of the Health and Safety Executive (HSE) in London.

Such a process is more complex, less certain in its results and more protracted, but simple reliance on expert authority-however prestigious-is less and less certain to carry acceptance, he said.

Mr. Locke was delivering the Alexander Redgrave Memorial Lecture at the Royal Institution on the theme 'The Politics of Health and Safety'. He said that decisionmaking based solely upon the judgement of a group of experts or on a quasi-judicial process is to assume that there is a single right answer: that any differences of opinion as to what should be done arise from ignorance or misunderstanding or a failure correctly to interpret the facts, and will be resolved by the logic of the expert.

The real situation, he maintained, is quite different. Decision-taking in health and safety should be a two-stage operation: firstly, by making an analysis of the nature and scale of the potential hazard and the means and cost of reducing the chances of anyone being hurt and reducing the number of people a risk-a task for the experts, and secondly, deciding whether the risk is one to be taken, or whether resources should be used to reduce the hazard or whether, in extreme cases, the operation should be abandoned altogether.

"Unless the experts have concluded that, to a high degree of certainty, there is no risk at all involved, then this second stage must be gone through. These decisions too can be left to the experts-and often are. The experts may well have a special contribution to make because of their understanding of the nature of the hazard. But, in my view, they should not take such decisions alone.

One way or another the people involved in the operation, those who bear the risks, and those who share the benefits, must also be involved. The differences in 'interest' must be identified, acknowledged and reconciled. That process is the real politics of health and safety"

Health and Safety Commission

Mr. Locke explained that the Health and Safety Commission (HSC) is composed of representatives of the main interests concerned with health and safety and welfare issues, and its structure reflects a particular view of how to handle the politics of health and safety. Employers and trade unions represent obvious interests. Local authorities to the CBI, nor because they are enforcement authorities for substantial parts of the legislation, but because, better than anyone else, they represent the general interests of society, particularly where work activities impinge on the general public.

Some critics have said that the Commission is an inappropriate body to take decisions on health and safety because it does not have the necessary expertise. "This is to wholly misunderstand the process involved", he said.

The Commission has set up a series of subordinate bodies to consider particular issues, each, in turn, setting up its own working groups on particular problems. Their common characteristic is to include people representing the main interests involved (but knowledgeable about the problems), as well as 'independent experts'.

Mr. Locke said: "Hopefully, these groups will reach an agreement. They usually do. If they don't the issue must be raised to higher levels of the structure: if necessary in the end it must come to the Commission itself.

"At each stage, the attempt is to reach agreement on a course of action which everybody can live with, even though it is not exactly what they desire. No single right solution is assumed.

"What is finally agreed may seem wrong-headed to some of the experts. The Commission has on occasions reached or endorsed conclusions which differ from those of myself and my colleagues. That is not important. What is important is the agreement".

Reconciling Interests

Mr. Locke said it is asked why should those with differing interests reach an agreement? There are two kinds of answer.

Firstly, at the "conceptual level" , most of society wants agreed rules to the game rather than anarchy. Better, said Mr. Locke, for a manager, for a trade union official, to have an agreed national control limit for asbestos or lead, than to have to settle every argument at the works level with no agreed standards to refer to. Better to have an agreed emission standard for dust from a cement works, than for the management and the people living around to be in continuous argument about what is reasonable.

Secondly, at the "practical level", the Commission has shown it can get such agreements, such as the regulations submitted to Ministers on lead, dust in coal mines, first aid, diving, and notification of accidents and dangerous occurences. Agreed negotiating positions in relation to EEC Directives have also been arrived at by the Commission-even for such a controversial and emotional issue as asbestos.

"The process is slow", said Mr. Locke, "though not necessarily slower than the regulation-making process in Government Departments. It requires patience-both by those involved in negotiation, and by those, like the Executive or Ministers, who are anxious for an early outcome. But once an agreement is reached it has a compelling force stronger than a mere acceptance of authority" .

2,4,5,-T

In order to illustrate the process "better than generalities", Mr. Locke briefly discussed three cases-acrylonitrile, Canvey Island and the herbicide 2,4,5,-T. Regarding 2,4,5,T, he explained that trade union members handling the chemical became disquieted with reports of illness among workers which might be due to the pesticide. Representatives of the unions had discussions with the expert advisory

committee reviewing the safety of pesticides and appointed by the Minister of Agriculture, but were still unsatisfied. Members of the union were told not to handle the chemiCal and some public authorities ceased to use it.

In early 1980, the issue was raised at the Health and Safety Commission's Toxic Substances Advisory Committee, which agreed to measure operator exposure in factories and farm activities, but was unable to do so because manufacture had ceased, and it could not find out where (if anywhere), it was being sprayed. More recently the committee has considered whether the present labelling is adequate-"probably not", said Mr. Locke-and asked the Commission's Agriculture Advisory Committee to look at various aspects of its use.

"What has arisen," said Mr. Locke, "is a situation in which a major interest has refused to accept the judgement of an expert advisory committee-or the Minister's acceptance of that judgement. The unions are, in fact, seeking to get a ban in practice.

"Clearly a most unsatisfactory situation has developed. Whether it could have been avoided if the unions and other interests concerned had been associated with the decisions as to whether 2,4,5,-T was safe to use, no one can be sure. I think it could have been."

Public Consultation

Mr. Locke emphasised the need for adequate opportunities for those in society affected by proposed legislation to study drafts and discuss them in detail with those engaged in the drafting.

"Fortunately nearly all health and safety legislation in future will take the form of regulations drafted by the Health and Safety Commission. The Commission's policy-which has my enthusiastic support-is to consult fully and publicly not only about the substance of regulations but also about their legal drafting."

The Individual Workplace

As at national level, the same differences of interest occur at the individual workplace when handling health and safety issues, said Mr. Locke, discussing the system of appointing workplace safety representatives.

He suggests four requirements necessary for the system to produce results in terms of improved safety and welfare: no concealment either by management or workers of health or safety problems; acceptance of national standards as "the ?orm" at any workplace; willingness to compromise; and mdependent expert appraisal, such as by the HSE or consultants, university departments etc. to this should be the contribution-by far the mam one-made by the professional health and safety staff working within an organisation such as the Institution of Occupational Safety and Health or other institutions representing occupational health services hygienists and others. "These professionals are paid for the employers. But to fulfil the role I have sketched, they must not be regarded by the work force as being in their employers' pocket. They must be professional in the full sense of the H.azards must be honestly and fully analysed. n must not be withheld. Where necessary, adVIce must be obtained from the HSE or elsewhere. mprovements in health and safety performance demrd bet.ter professional skills-perhaps more people with better training and fuller qu I IcatIons.

"Many I d emp oyers have adequate services available. Others 0 not. As safety representatives become more knowledgeable and experienced, they will demand better

professional services. If employers do not have recourse to adequate professional skills the politics of health and safety will become more strident and more divisive at the workplace," said Mr. Locke.

Health and Safety Executive

The role of HSE in the politics of health and safety was also discussed by Mr. Locke. It acts as the expert adviser of the Health and Safety Commission, he said, providing assessment of the scale of any problem such as appraisals of toxic chemicals or hazardous installations. "It forms part of the system of expert appraisal which is the pre-condition of sensible decision taking."

In addition, the health and safety inspectorates, which form part of the HSE, and who are "traditionally the defender of those too weak to defend themselves", must ensure that proper regard is paid, where necessary, to the interests of workers, members of the general public and firms.

"But the Executive and its staff also have an important role to play in the process I have described of reconciling the various differing interests. We provide the chairmen and secretariat of most advisory committees. At the workplace inspectors will often be called in when management and unions are finding it difficult to reach ageeement-not just to provide facts, but to suggest solutions which may be acceptable. Similarly we can assist in finding acceptable compromises between the needs of an industrial society and the legitimate interests of local communities.

"If today our role is less of a crusade and more of a negotiation with other interests-then that points perhaps to the current state of the politics of health and safety" .

Elsewhere in his lecture, Mr. Locke examined the role in health and safety of the overtly political institutions-the parties, Parliament, Ministers, concluding that party politicS do not "as a rule" cut deeply into health and safety Issues.

also the role of "interest groups in on and safety Issues, including the and specialised voluntary bodIes which, m the malO, represent the interests of "the general public"

Mr. Locke also spoke of the efforts being made to achieve common EEC standards on a number of health and safety issues. "Personally I believe in common EEC standards. But they must be common standards of enforcement as well as statements of objectives," he said.

Relocatab le Safety Store

A prefabricated steel store for HFL's and Petroleum, available for instant use with minimal site work, incorporating standard requirements for container storage such as ventilation and retention.

These stores are available in seven sizes with double skin construction if required giving up to 2 hours Fire Resistance, but since the Company manufacture their own stores 'specials' can be made to order.

The Company also provide safety containers, cabinets, bins and drum handling equipment and will shortly be offering portable stores for LPG. They employ a qualified Fire Consultant who can advise potential customers. Further details can be obtained from:Safety Unlimited, The Potteries Industrial Estate, Southend Lane, Wood Green Road, Waltham Abbey, Essex EN9 3SA.

Telephone: Lea Valley 715370.

Uplifting Experience?

T he Dover E ngineering Works Ltd of Dover, Kent have marketed a lightweight lift ing device for manhole covers. As

can be seen by the photograph the young lady handles it well on her own! The device weighs 18 kgs and can be carried in the boot of a car, it works on a fulcrum action Details from the company on (0304) 203545

,

PETROL / FUEL OIL IN TERCEPTOR

The SWAINCEPTOR is designed for prevention of contaminated liquids and solid pollutants from entering sewers or watercourses. It's typical uses are garage forecourts, workshops, vehicle washdown areas, fuel distribution points and other industrial applications requiring pre-treatment of liquids to the satisfaction of the Local Authorities before direct discharge into sewers or watercourses.

Installation Instruction

oExcavate hole size required:

2500 litres 2200mm by 2090mm high. 4000 litres 2470mm long by 2200 wide by 2090mm h!gh 6000 litres 3270mm long by 2200 wide by 2090mm high.

Add invert depth (depth from ground level to inlet pipe).

eMix sufficient concrete on 1.2.4 concrete mix to house base of unit:

2500 litres 1800mm diameter.

4000 litres 2470mm by 22oomm. 6000 litres 3270mm by 22oomm.

Thickness of concrete required for all three sizes is 200mm. d I h 't to the WET concrete ensuring Place rope through the holes located at the base of the neck an ower t e union the base of the unit is well seated on the wet concrete.

With the unit installed allow the concrete base to set hard .' It' I t/ outlet sockets to drain run. The inlet pipe also Once the concrete base has set backflll with P grave up 0 In e acts as ventilation pipe.

f left open when conditions are wet it is The unit is now ready for filling with water. (If excava Ion IS adlvisable to part fill unit with water to prevent lifting.

. 'Id . f r manhole cover and f rame to suit . (Neck

Construct concrete apron over the Unit and bUl In 0 eX/tensions are available to suit invert depths as required).

J . W . Sw ain Plastics Limited

Byron Street, Buxton, Derbyshire

Te lephone: Buxton (0298) 2365

Unattended Self Service

R . .lones - Suffolk County Council.

The Suffolk Trading Standards Department has recently given detailed approval under the licensing provisions of the Petroleum (Consolidation) Act 1928 to a proposed unmanned self-service filling station.

The facility will consist of a 10,000 gallon double compartment underground storage tank, which will feed two, three product dispensers, one being linked to a conventional note acceptor unit, and the other being linked to a G.E.C. Money card unit.

The site is on the spine road of an industrial estate which is situated between two large housing estates, and at present comprises a car showroom, offices, and workshops A conventional attended self-service filling station IS operated by the company in an adjoining town.

Constructional requirements are very similar to those for a normal "after-hours" unattended self-service facility with the addition of the following:-

(i) the action of opening the emergency equipment cabinet should automatically break the power supply to each pump;

(ii) all notices giving emergency action instructions should be of plain block red letters, at least 50 mm high, on a plain white background·, (iii) an internally illuminated notice should be maintained near to the filling area, bearing the words "PETROLEUM SPIRIT HIGHLY INFLAMMABLE NO SMOKING SWITCH OFF ENGINE" (the letters should be plain block red at least 100 mm high on a plain white background) (iv) a notice should be conspicuously displayed indicating:

WARNING

(a) NO PERSON UNDER THE AGE OF 15 YEARS MAY HAVE ACCESS TO PETROLEUM SPIRIT. (b) ONLY METAL CONTAINERS WHICH CAN BE SECURELY CLOSED ARE LABELLED "PETROLEUM SPIRIT HIGHLY INFLAMMABLE" AND DO NOT EXCEED 25 LITRES (5 GALLONS) CAPACITY MAY BE FILLED WITH PETROLEUM SPIRIT.

(Again the sign should be as for (ii) above).

Instead of the site having an emergency telephone, approval has been given to the installation of a British Telecom ABC (Alarm By Carrier) alarm system which be connected directly to the Suffolk Fire Service o;tr?l room (this is subject to the Fire Service acceptance). aSIcally the ABC system uses ordinary telephone exchange lines to carry the signals between the premises and the local exchange where a dedicated ABC network takes Over for the onward transmission of alarm signals to the At .the centre an incoming alarm signal ggers audIble and Visual alarms which are cleared by the centre operator when acknowledging receipt of the signal. When acknowledged, the visual information is transferred to a paper printout. Forecourt operation of the ABC would be a "break glass" alarm point housed in the emergency eqUipment cabinet.

The G.E.C. money card systems has BASEEFA approval, and is similar in operation to the Fleetcard system as operated on CONOCO Rapidiesel facilities.

A magnetic moneycard, card acceptor unit and record printer, control unit, air conditioning unit and updata keyboard are the five main items of the system.

The card is a coded plastic magnetic card which identifies the card issuer as well as the card holder and stores spending power.

The air-purged card acceptor unit is located on the pump island and houses the card read/write unit and the computer, which checks that the card is valid, and that the date has not expired. The acceptor unit is equipped with a keyboard on which the customer is required to enter a four digit· personal code to prove ownership. The unit also receives pump information and when the transaction is completed the read/write unit "writes" the diminished spending balance on the card. In this installation it is envisaged that the card acceptor unit will only accept cards issued by this site, and the cards will be of a deposit type.

After each transaction the card holder will receive a printed paper statement showing the date, opening balance, transaction, closing balance and VAT rate.

The control unit will be situated in the nearby showroom offices as will the updata keyboard unit.

The updata unit is a simple desk top manual terminal, equipped with keyboard display, totalisers and security lock and is used for recharging moneycard balances. The updata unit is connected to the control unit.

(To satisfy the planning approval time limit, the site owner is initially going ahead with the tank installation and basic forecourt construction.)

Many thanks to colleagues in Berkshire for their assistance and advice concerning this project.

Talking Point Notes and News London News Shell on the Maplins Ignition by Radar Contents Gauges Shell Road Tanker New Products Testing Time Glass Fibre Manhole Legal Proceedings Tank Linings AGM

Chairman's Address Death Involving Petrol Letter

Crossover of Petrol and Heating Oil Sub Standard Premises Pipeline Corrosion Tank Explosion Branch Meetings New Conveyance Regulations Pioneers of Petrol Gas Freeing Tank P.T.F.E. Tape Politics of Health and Safety

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