What Does Pigging Mean?
Pigging refers to a technique of cleaning or inspection of pipeline through recovering trapped products in the pipelines without stopping operation. It is done through inserting a device known as pigging pigs into the process pipelines.
Pigging operations have been practiced for many years in the oil industry to clean big hollow pipelines. Now it is also used for cleaning smaller diameters with increased efficiencies and reduced costs.
A pigging system is also used in lubricating oils, paints, chemicals, toiletries, cosmetics and foodstuffs. It is also used to clean oil and gas pipelines. In a multi-product pipeline, pigs are very helpful to separate different products.
Corrosionpedia Explains Pigging
In pipelines, pigging refers to various maintenance operations of cleaning and inspecting pipelines with the help of a device known as a pig. Pigging is performed with the flow of the materials within the pipeline.
This operation is done by inserting the pig into the pipeline from the source to the endpoint. During the travels of pigs through the pipeline, it brushes out the trapped product and cleans the pipe walls. Therefore the pipeline is made ready for the next product transfer after pigging. Pigs may be used in following cases:
- Internal cleaning
- Hydrostatic testing and pipeline drying
- Internal coating
- Liquid management
The pigging process ensures the smooth flowing of products and reduces chances of product contamination within the pipeline. It removes built-up debris, which ultimately helps to protect from degradation of the pipe wall over time.
Pigging is also used in the inspection of pipelines to collect information regarding:
- Temperature and pressure
- Corrosion/metal loss
- Diameter, bends and curvature to verify pipeline integrity
Pigging is also used to measure cracks, weld defects, surface pitting and areas of crushing/deformation.