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Copyright © 2001 Scientific Surveys Ltd. All rights reserved. 1

Pipeline pigging – an industry overviewby J L Cordell

On-Stream Systems

Contents of this Paper:

• Introduction

• The early days

• The present situation

• The challenge of the future

• Conclusion

• Figure 1: Partial list of currently available intelligent PIG services

• Figure 2: Partial list of conventional PIG manufacturers

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Pipeline Pigging and Integrity Monitoring Conference: Houston, 1989

2 Copyright© 2001 Scientific Surveys Ltd. All rights reserved.

Introduction

Unlike many aspects of modern life such as electricity and the telephone, the pipeline pig was not the result of some sudden inspiration. It began as a result of the, then new, oil pipeline industry's needs to clean the wax anddirt from it's lines and so maintain a reasonable through-put.

The very earliest pigs are believed to have been made from balls of straw wrapped with barbed wire. It istherefore no surprise that there is no known record of anyone claiming the responsibility of having made the firstpipeline pig! For much the same reasons there is no record of where the first pipeline pig was used, and even thequestion of how the pig got it's name is still hotly debated.

There are, however, a number of reasonable assumptions which can be made; firstly there seems to be little doubtthat 'pigs' were born in the oilfields of either Texas or Oklahoma, so it is most appropriate that this, the firstconference on pipeline pigging technology in the United States, should be here in Houston which, in relativeterms, cannot be very far from where the first-ever pig made it's first run.

Secondly, it would be reasonable to assume that it would be quite a small pig, perhaps something in the region of 4-6in diameter. It is doubtful whether it was called a pig in those early days, for the 'pig' as we now know it waspreceded by the 'go-devil'. In fact, one of the most plausible explanations for the use of the term pig was that

when the go-devil travelled through the line, equipped as it was with leather driving discs, spring-loaded starwheels and steel scraper blades, it made a screeching noise similar to that made by farmyard pigs. The otherexplanation was that when a go-devil was pulled from the pipeline covered in wax and dirt it looked somethinglike a farmyard pig which had been rolling in the mud.

The very fact that it was called a pig - a somewhat derogatory, or at best amusing, term - points to the fact that itwas not taken very seriously as a piece of engineering. Since those early days, though, things have changeddramatically. Today's intelligent pigs utilize state-of-the-art technology and even this in some cases, is failing tofulfil the needs .......

So how did we get to where we are today, and what might we expect tomorrow?

The early days (up to c.1960)

It probably didn't take very long for operators to realize that the purpose-built go-devil was far more effective atremoving wax and dirt than the ball of straw wrapped with barbed wire. As pipelines became longer and larger sothe use of a purpose-built pig became standard practice.

Gas-gathering systems with their attendant problems of condensate drop-out, needed a 'squeegee' rather than ascraping action - and they needed it frequently. This gave birth to the sphere pig which did, and still does, lenditself admirably to automated pigging systems designed for the removal of condensates.

As with so many other things, it was probably the Second World War which gave the impetus to the developmentof the cleaning pig as we know it today. The German U-boats sitting off the East coast of the United States took a

terrible toll of American shipping taking crude oil up the coast, and this led to the construction of the first 'big-inch' pipeline.

The pigs which had been used in the relatively-short, small-diameter lines until then, proved to be incapable of withstanding this gruelling trip and few, if any, reached the other end intact. This led to the development of muchmore robust pigs incorporating heavier springs, thicker and tougher driving cups, and much stronger and largerbody construction. This general approach to pig design seemed to take hold and by the end of the 1950s themanufacturer's were able to offer complete size ranges of numerous different types and styles of pipeline pig.

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Pipeline pigging: an industry overview


The 1960's

These were the 'golden years' of pigging - when innovation was the name of the game. This was a time when theoil and gas industries in particular began to accelerate, especially in Europe and the Middle East, and pipelineswere designed without much thought being given to the need for pigging.

The pig manufacturers, who always seem to enjoy a challenge, rose to the occasion, and designed and built some

of the most exotic pigs that have ever been seen. There were pigs designed to go around zero-radius elbows -which they usually did. There were pigs designed to traverse rectangular-port plug valves - which they sometimesdid. And there were pigs designed to clean out heavily-contaminated pipelines in one pass - which they rarelydid.....

It was a period of research and development in the pigging industry, for as pipelines got even longer and larger,operated at ever higher pressures and became strategically more and more important, so the need for effective andmore efficient pigs became paramount.

When AMF Tuboscope ran the first commercially-successful intelligent pig in 1965 it heralded a new era for thepigging industry. It was now necessary to differentiate between the conventional pig used for cleaning andperforming a service, and the intelligent pig which was to be used for gathering information.

AMF's Linalog pig is used to detect corrosion, and shortly afterwards T D Williamson announced its Kaliper pigwhich detects buckles, dents and other reductions in diameter. Both Linalog and the Kaliper pig went through anextensive development period prior to their introduction. Now with some 20 years further development andexperience behind them, they are still in use, but with greatly enhanced performance.

The present situation

a) Intelligent pigs

Even though AMF Tuboscope and T D Williamson had demonstrated that valuable information could be obtainedby running an intelligent pig, it took a considerable time for this concept to gain acceptance. Indeed, in someplaces there is still a degree of scepticism.

Over the last 10 years or so there has been a dramatic increase in the number of intelligent pigs and servicesavailable. There are at least eight different metal loss/corrosion pigs, five geometry pigs and various others: fordetecting cracks, for visual (photographic/video) inspection, curvature and bend detection, leak detection, waxdeposition measurement, sampling, etc. (see Fig.1).

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Figure 1: Partial list of currently available intelligent PIG services

Metal Loss Geometry Cracking

AMF Tuboscope (Linalog) EPS British Gas

British Gas IPEL Kopp IPEL Kopp

IPEL Kopp RTD H.Rosen

NKK H.Rosen

RTD TDW

H.Rosen

Vetco (Vetcolog)

Photographic/Video Curvature/Bends Leaks

Magnaflux EPS IPEL Kopp

NKK IPEL Kopp H.Maihak

H.Rosen H.Rosen H.Rosen

Wax/Deposition Sampling

H.Rosen IPEL Kopp

The cost of developing these tools is staggering. British Gas alone has invested somewhere in the region of $200million. No actual figures are available, but it is reasonable to assume that at least one billion dollars has beeninvested in the development of intelligent pigs to date.

It is not surprising therefore that mergers such as those between IPEL and Pipetronix have taken place, and itwould not be surprising to see others in the near future. Certainly it would seem to make sense, for although theenvironmental and legislative pressures are constantly increasing the market for intelligent pigs, the intensecompetition and the tight economic climate are making the business increasingly difficult. The question musttherefore be asked, whether all of those presently serving the market can indeed survive.

b) Conventional pigs

If competition among intelligent pig manufacturers is considered to be 'strong', then competition amongconventional pig manufacturers must be considered 'fierce'.

Because of conventional pigs' basic simplicity, there are a large number of manufacturers vying with one anotherto supply the needs of the pipeline industry. There are over 25 manufacturers (Fig.2) supplying a standard rangeof off-the-shelf pigs, quite apart from the many contractors and other organizations who make up their own pigsutilizing standard components. Such competition results in very small profit margins, and therefore an inability toinvest in the fundamental research which would be so valuable in developing more efficient pigs.

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Figure 2: Partial list of conventional PIG manufacturers

Carver (Walters, USA)

Cotton (Tulsa, USA)

Coulter Services (Houston, USA)

Dowell (Gel Pigs)

Enduro Pipelines Services (Tulsa, USA)

Fluorocarbon (Houston, USA)

GD Engineering (Worksop, UK)

Girard (Multinational)

INPIPE (Catterick, UK)

IPEL-KOPP (Multinational)

JPT (Ijsselstein, Holland)

Knapp (Multinational)

McAlpine Services & Pipelines (Ellesmere Port) (Gel pigs)

McKenna & Sullivan (Northhampton, UK) (Gel pigs)

MainTech International (Stafford, USA) (Gel pigs)

Maloney (Houston, USA)

NOWSCO (Multinational)

PEAS '82 (Huis ter Heide, Holland)

Pipeline Dehydrators (Houston, USA)

Pipeline Engineering & Supply (Richmond, UK)

Prematechnik (Frankfurt, Germany)

Oil States (Arlington, USA)

H. Rosen (Multinational)

S U N (Broken Arrow, USA)

Unipipe (Montrose, UK)

T. D. Williamson (Multinational)

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Some operators are known to be carrying out ad hoc studies of certain aspects of pig efficiency and this is helpful.However, it would be a great deal more beneficial to both the operators and the manufacturers if they could pooltheir resources and develop an industry-wide research programme.

One of the difficulties until now has been the fragmented nature of the pig manufacturers, caused by the highly-competitive nature of the business. However, towards the end of last year moves were made by On-StreamSystems Ltd (who provides an independent source of information and advice on pigs and pigging) to find out if the pig manufacturers were interested in forming a Pipeline Pigging Equipment Manufacturers' Association.

The initial response was very encouraging indeed. Apart from the more obvious advantages of such anAssociation, it could provide the channel through which all the manufacturers could be represented and speak asone, in the creation of an international research and development programme into either conventional orintelligent pigging and its related equipment.

The challenge of the future

From its earliest beginnings, the pipeline pigging industry has had to respond to the needs of the pipelineoperators, and this same situation still exists today. However, the needs of the operators and of the industry

generally are the result of a great many factors; none of these is perhaps any more, or less, important than theother:

Speed/service

There has never been a period, at least in peace-time, when the speed of response has been so important. Withmarginal fields coming on stream which have a projected life of only a few years, the pressure on manufacturersto provide a rapid turnaround will increase still further and this will occur during a period when the specificationand design requirements will be more demanding than they have ever been before.

Environment

Environmental pressures are growing almost by the minute. Generally, the oil and gas industry has a good recordfor environmental concern. Sadly, the same cannot be said of a number of other industries, and the environmental

lobby is forcing governments throughout the world to react. From an environmental point of view at least then,we can expect to see a great deal more......

Legislation

It can only be a matter of time (and this will be sooner rather than later) when tougher legislation is introducedrequiring pipelines to be regularly inspected. If the pipeline industry is to avoid the huge losses caused by ashutdown, this will have to be by intelligent pigs. These will take time to develop - and time is getting very shortnow.....

Economics

The economic pressures are arguably greater than any other single factor. For companies, and even countries, it is

almost literally a matter of life and death. Operators will have to face the fact that the suppliers will be unable togive them 'free samples' as many have done in the past, and the pig manufacturers will not be able to supplyequipment or services that don't come up to specification. Commercially, business will become much harder and,sadly, less personal than it has been in the past.

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Competition

Under the circumstances already described it is not hard to see that competition is likely to become even stronger.This is hard to imagine as things stand at the present, so we might expect to see a good many more mergers and joint ventures. The survivors will be those that plan most effectively. Any good business plan must include athorough competitor, and self analysis. From this the respective strengths and weaknesses become apparent, andwe can therefore expect to see some 'marriages of convenience'.

Technology

Technology is where both the greatest challenge and the greatest opportunity undoubtedly lie.

Pipelines, particularly those offshore, are becoming smaller and the challenge to the intelligent pig manufacturersto pack highly-sophisticated electronic equipment into a very small diameter pig is obvious.

Add to this the need for perhaps bi-directional capability for the inspection of flow lines, plus a requirement toperform in full well-stream fluids with all the attendant problems of temperature, multi-phase conditions and dirt,and we have some idea what the industry will face in the very near future.

Fortunately, the technology on which the intelligent pig manufacturer relies is also progressing at a dramatic pace.One manufacturer was able to increase the memory storage capacity of his intelligent pig by four times over a

period of only nine months due to micro-chip development work.

So, although the activity, particularly in the area of subsea exploration and production, is gaining pace, thetechnology available to the pig manufacturers, given sufficient time and money, is likely to be able to keep up.

But it's not just the intelligent pigs which face a technological revolution. Some of the developments which are'just around the corner' include:

• pigging flexibles and full well-stream fluid over long distances;

• automatic subsea or remote, unmanned pig stations;

• pigging small-diameter laterals;

• pigs capable of cleaning a small line then travelling on through a trunk line perhaps 10 sizes larger.

Undoubtedly, conventional pigs will undergo a renaissance - a return to the 'golden age' - but with a lot moreprofessionalism than in the past.

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Conclusion

It is clear that pipeline operators and pig manufacturers are facing some major new challenges. In the past theyhave met these challenges, and no doubt they will do so in the future. But we can expect to see them do so in avery different way.

It is perhaps coincidental that the six major factors mentioned, which the industry must face:

Speed/ Environment/ Legislation/ Economics/ Competition/ Technology

form the acronym -

S E L E C T

The pipeline industry will become more critical when it SELECTS its pigs, SELECTS its procedures andSELECTS its suppliers.

The pig manufacturers will be more discriminating when they SELECT their designs, SELECT their markets andSELECT their partners.

In short, in a period of just about 100 years pipeline pigging has evolved from a "good 'ole boy" wrapping barbedwire around a bunch of straw, to a highly sophisticated - one might even say, a very SELECT - industry.

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