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Author Topic: Pigs and Intelligent Pigs  (Read 97 times)
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Tim of Aclea
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« on: March 19, 2017, 17:27:36 PM »

Some bits from my forthcoming book on the above subject plus a couple of photos

'In order to keep the pipelines clean, a metal rod with circular wire brushes and rubber washers was inserted into the pipeline at one storage depot or pump-station and then removed, together with any accumulated dirt, at the next.  In a Pathe News film of the pipeline system, the device was described as ‘the housewife’s dream of a perfect flue cleaner’.   These cleaning devices were initially to be referred to as ‘Go-Devils’ but were later called ‘Cleaning Pigs’.  Afterwards, other devices that were to be inserted in the pipelines, for purposes such as inspecting the pipelines, were also referred to as ‘Pigs’.  A three letter acronym of ‘Pipeline Internal Gauge’ has since been made up to justify the use of the term ‘Pig’.'

An important development in terms of pipeline safety undertaken by BNOC was the introduction of ‘intelligent pigging’ of the pipelines.  Cleaning pigs (originally referred to as ‘go-devils’) had been used from the very start of the pipeline system.  Sphere pigs (a hollow rubber ball, inflated with water) were also used at one time to separate parcels of differing products.  However, it was found that, properly handled, different products did not mix with each other to any great extent and so the use of sphere pigs was discontinued.   
The development of the ‘intelligent pig’  was spurred by a number of massive explosions caused by leaks on gas pipelines, particularly in the United States.  It seemed that certain companies were more prepared to tolerate the price of paying for such explosions and resulting damage than to undertake the cost of developing methods of avoiding such explosions.  The British Gas Corporation, which was in the process of developing their national grid, decided that they could not afford to take such an attitude.  Professor Ernest Shannon, the director of on-line inspection for British Gas, set up a 350 strong team to develop a device that could be inserted into a pipeline to detect defects such that they could be repaired before a leak occurred.  The intelligent pig needed to be able to detect deformities, corrosion and cracks in the pipe wall.  The pig carried magnets that created a field by which the thickness of the pipeline could be measured and ultrasonic probes that would detect pipeline cracks.   

Before an intelligent pig could be run in a pipeline, it was necessary to first send a calliper pig, which would check that the bend radii on the pipeline were suitable for pigging.  Next a dummy pig, which had the same geometry as the intelligent pig, would be sent through the pipeline to check that the intelligent pig could go through the line without either getting stuck or being damaged.  The cost of the development of the intelligent pig had been in the region of £50million and they were expensive to build.  This made the overall cost of running intelligent pigs in a pipeline very costly.   
Not all pig runs proceeded as smoothly as intended.  In the early 1980s a pig became stuck in the W/E pipeline and the engineer in charge decided to increase the line pressure to try to ‘free it up’.  This did succeed to the extent that the pig suddenly broke loose but unfortunately it had now gained such a velocity that it shot straight out of the pig trap and flew across a field.  Fortunately no one was hurt, but passers-by really did see a ‘pig that flew’.
 
Tim

Photos cleaning pigs
Damaged intelligent pig
Pigging facilities


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Cleaning pigs.jpg
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Man of Kent1
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« Reply #1 on: March 19, 2017, 18:46:59 PM »

Wasn't there a scene in a James Bond film when he was in an oil pipe being 'chased' by one of these things? Bond eventually emerged unscathed, uttering the immortal lines (more or less!):
'I was just taking my rat for a walk!'
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Tim of Aclea
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« Reply #2 on: March 20, 2017, 10:12:16 AM »

From memory, in Diamonds are Forever, in a typical 'we can easily kill James Bond but we must do it in a weird way' scene, he is left inside a pipeline under construction.  He shorts out some sort of 'pig' and then the workmen come to find out what went wrong and so let him out.

Also in The Living Daylights a Soviet General who claims he wants to defect out to the West is smuggled out in a pig in a gas pipeline.  However, unless the pigs over there travel at a far greater speed than the ones I am used to, he would suffocate before he reached the west.  The normal speed of a pig as it is carried along by the fluid (oil or gas) is about a fast walking speed.

Tim
 
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