Understanding Pigging and Pig Valves in Industrial Pipelines

Pigging is a method of introducing a mechanical device, commonly referred to as pigs or scrapers, inside a pipeline to perform various internal maintenance operations. The term PIG is said to be an acronym for “Pipeline Intervention Gadget”. The process has been used for many years to scrub large diameter pipelines in the oil and gas industry. Today, the use of smaller diameter pigging systems is growing in many continuous and batch processing plants, as plant operators are looking for improved productivity and ways to reduce costs.

Pig valves were successfully implemented into the oil and gas industry over five decades ago. They are used extensively on oil and gas pipelines throughout Western Canada and the United States. They provide an efficient way to launch and retrieve pigs in the oil and gas industry, water treatment facilities, or anywhere critical pipelines need to be maintained.

Pigging is used to mechanically sweep and/or visually inspect inside of the pipeline. The pig or scraper is moved through the line by the differential pressure caused by the process fluid moving past at a higher velocity. The pig is inserted into what is known as a “pig launcher” (or launching station) which is a part of the pipeline with an oversized diameter to accommodate the installation of the pig. The launching station is then closed and the pressure driven flow in the pipeline is used to move the pig down the pipe until it reaches the receiving trap (the pig catcher or receiving station) where it can be removed. Pigs are used daily in the operation of pipelines for a variety of reasons, the most common are: pipe cleaning for improved line efficiency; locating flow obstructions; pipeline inspection; separating different products flowing through the pipeline; corrosion control; air purge; water removal; and flow volume validation.

For more information about pigging valves, contact MSEC.

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