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Hydraulically activated pipeline pigging (HAPP) is a pigging technology applied for pipeline cleaning. The basic principle is that a pressure drop is created over a by-passable pig held back against a pipeline’s fluid flow. The pipeline fluid passing through the pigs cleaning head is accelerated by this pressure drop, forming strong cleaning jets. These jets are directed onto the inner wall in front of the pig, removing all kinds of deposits. Generally, this technology transforms the kinetic energy of the pipeline fluid into a locally available differential pressure that in this case is used to create cleaning jets but can also be used otherwise. ==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 the debris is scratched away. Therefore several, sometimes many, pig runs are required to clean a pipeline. Hydraulically activated pigs apply high pressure liquid jets either supplied by high pressure hoses (depended) or made available by the kinetic energy locally available. Depended hydraulically activated pigs are limited in reach due to the hose which needs to be inserted into the pipeline and guides the cleaning head. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hydraulically activated pipeline pigging」の詳細全文を読む スポンサード リンク
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