PPSA Celebrates 20th Anniversary

In 2010, the Pigging Products & Services Association (PPSA) celebrates its 20th anniversary. Based in the UK, PPSA was founded in 1990 to promote the knowledge of pigging and its related products and services by providing a channel of communication between the members themselves and with users and other interested parties. Its members are comprised of companies that manufacture or market pigging products or services, companies connected with the industry or individuals with an interest pigging products or services.

Pigging is essential since almost all of the bulk fluids used in the modern world are transported by pipeline. The fluids include 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 then, 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 all of these are easily accessible – pipelines are not! 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 or for removing unwanted gases or liquids – or more sophisticated ones for detecting damage, corrosion, movement of the pipe and other potentially serious problems.

Why “Pig”?
There is some debate about the origins of this name, but it almost certainly originated in the oil fields of Texas in the early 20th century. In those days, crude oil pipes were cleaned by stuffing barbed wire and straw into one end and pumping this bundle through to scrape off the wax deposits. This created a screeching sound which someone suggested was “like a pig’s squeal.” They have been referred to as “rabbits” or “moles” too, but attempts to change the name to something a little more technical like “scraper,” or even simply “tool” have generally failed. It seems that the pipeline industry is secretly quite proud of this rather strange appellation.

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 “inline 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 analyze 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 (1,000 mm) diameter, 100-mile pipeline (i.e. a relatively short and not especially large pipeline). The ILI tool may travel at speeds of up to 10 mph (16 km per hour) which means it must inspect, analyze, then store the data for 140 square feet (13 square meters) of pipe wall - every second for some 10 hours!