The whole hog

Lloyd Pirtle celebrates 20 years of the Pigging Products & Services Association and reviews why its creation was so important.

“Pipeline pigging has been practised for well over 100 years, but as pipelines became longer and strategically more important, pigging had to be taken more seriously”
-Lloyd Pirtle

Almost all of the bulk fluids used in the modern world are transported by pipeline. Crude oil, natural gas, refined products, water and countless others. To travel through a pipeline, fluids must be pumped. Pumping requires pressure to be exerted on the fluid and this pressure creates stress in the pipe wall. Stress can cause failure – and failure of a pipeline could be catastrophic. Clearly, the integrity of any pipeline is of paramount importance.

Any vessel or structure subjected to stress must be regularly maintained and inspected. Aircraft, boilers, buildings – even regular servicing of an automobile are typical examples. But, unlike pipelines, all of these are easily accessible. Whether traversing land or sea, pipelines are buried, so the only way to ensure their integrity is from the inside. Obviously maintenance engineers or inspectors cannot be sent through a pipeline, so it is necessary to devise some other means of doing this. The answer is to use tools, which are known as pigs. Pigs can be used for cleaning and removing unwanted gases or liquids – or more sophisticated ones for detecting damage, corrosion, movement of the pipe and other potentially serious problems.

Pigs travel through a pipeline driven by the product flow - they are in effect free moving pistons. They can be subdivided into two broad categories: conventional pigs which are used to perform maintenance tasks such as cleaning or drying, and in line inspection (ILI) tools which provide information about the pipeline’s condition. Conventional pigs are usually very simple devices fitted with brushes and seals and are used on a routine basis. ILI tools are very different. They carry sensors to detect and locate any problems as well as the battery power and computer equipment to enable them to analyse and store all the resulting data.

To get some idea of the degree of sophistication required for ILI tools, consider the inspection of a 36-inch (approximately 1000mm) diameter, 100-mile pipeline (i.e. a relatively short, and not especially large pipeline).  The ILI tool, may travel at speeds of up to 16 kilometres per hour which means it must inspect, analyse then store the data for 13 square meters of pipe wall every second for around 10 hours

Pipeline pigging has been practised for well over 100 years, but as pipelines became longer and strategically more important, pigging had to be taken more seriously. Various ILI tools were made, but the real breakthroughs began with the advances in computer technology in the 1980’s. During this period, there was a proliferation of different pigs and services offered which made it difficult for the pipeline owners and operators to know what was available and to decide which, if any, was best for their particular circumstances. 

It became apparent that although it was important for operators to be made aware of the pigging products and services available to them, it was equally important for the suppliers to be made aware of the needs of the operators.

In 1989, Scientific Surveys Limited and Gulf Publishing Company held the first Pipeline Pigging Technology Conference in Houston, Texas. It was realised that, as most prospective members would be there anyway, the Houston Conference would be an ideal place to hold a meeting to discuss and finalise the formation of a trade association. The aims and objectives had to be established and prospective members had to be recruited. The pigging industry was very keen to get together and before the second conference opened in Houston in 1990, there were 19 provisional members. After the necessary legal formalities, the Pigging Products & Services Association or PPSA was finally incorporated on 1 May 1990.

Since then, PPSA has been a remarkable success story. Membership has risen from 19 to 90 and now includes virtually every organisation in the world that is involved with this very specialised and important activity.

For more information visit www.ppsa-online.com.