Hydraulically Activated Pipeline Pigging - Introduction To Pipeline Pigging

Introduction To Pipeline Pigging

Pipeline pigs are devices that are inserted into and travel throughout the length of a pipeline driven by the product flow. They were originally developed to remove deposits which could obstruct or retard flow through a pipeline (Fig. 1). Today pigs are used during all phases in the life of a pipeline for many different reasons.

Pigs used today can be divided into three categories (Fig. 2):

• Utility Pigs, are used to perform functions such as cleaning, separating, or dewatering.
• In Line Inspection (ILI) Tools, provide information on the condition of the line, as well as the extent and location of any problems.
• Gel Pigs, are used in conjunction with conventional pigs to optimize pipeline dewatering, cleaning, and drying tasks.

Generally for cleaning pigs, the cleaning force applied is the mechanical force between the pipe inner wall and the cleaning pig itself. This force is determined by the pig travel speed as well as by the hardness and shape of the cleaning edge: The faster the pig, the higher the cleaning impact on the deposits but at the same time only the surface of debris is scratched away. Therefore several, sometimes quite many, pig runs are required to clean a pipeline.
Hydraulic activated pigs apply high pressure liquid jets either supplied by high pressure hoses (depended) or made available by the kinetic energy locally available. Depended hydraulic activated pigs are limited in reach due to the hose which needs to be inserted into the pipeline and guides the cleaning head.