The accumulation of debris in pipelines is a common problem but a difficult one to manage safely and effectively. Typically we think of debris as sand produced into the pipeline or deposited during construction but it can also be mechanically recovered scale, corrosion and even welding goods.
To effectively remove any debris requires the use of mechanical scraper pigs but the risk of the pig sticking by building up debris in front of it can be severe depending on the balance between the pipeline diameter and the quantity of debris.
Another factor which complicates debris removal is that it is very difficult to accurately estimate the actual amount of debris in the pipeline and how it is distributed. All this creates risk and uncertainly.
In crude oil lines the situation is worsened by the fact that the debris that the client wants to remove can be oily, sticky and compacted so it is advised to try to clean and loosen the debris as part of any removal project.