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The pig is pushed either with a gas or a liquid; if pushed by gas, some systems [10] can be adapted in the gas inlet in order to ensure pig's constant speed, whatever the flow pressure is. The pigs must be removed, as many pigs are rented, pigs wear and must be replaced, and cleaning (and other) pigs push contaminants from the pipeline such as ...
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 pig's cleaning head is accelerated by this pressure drop, forming strong cleaning jets.
Behind this slug of liquid follows a slug of gas, until sufficient liquids have accumulated at the bottom to form a new liquid slug. Pigging slugs are caused by pigging operations in the pipeline. The pig is designed to push all or most of the liquids contents of the pipeline to the outlet. This intentionally creates a liquid slug.
Pipeline Filling (Flooding) – which can be carried out by propelling pigs through the pipeline with water or free flooding with water (normally for smaller or unpiggable pipelines). Hydrotesting – this is a process by which the pipeline in question is pressure tested to a predefined pressure above the operating design pressure of the pipeline.
In ideal situations, pipeline inspection gauges or a “PIG” (see Pigging) is used to inspect and ensure the safe operation of natural gas pipelines. About 63 percent of all natural gas pipelines in the US cannot be properly inspected using a PIG, or automatic robot in the pipes, because the pipelines are either too old or they twist and turn ...
Natural gas may move through a pipeline system typically at speeds of up to 25 mph (11.2 m/s), depending on pressures and pipeline diameters. For a pipeline system operating at a nominal pressure of 1000 psi (such as the UK National Transmission System ) compressor stations compress the gas from about 48 bar (700 psi) to 65 bar (950 psi).
Its Transco Pipeline system spans the Southeast going from New York to southern Texas, bringing natural gas to markets in 13 states. The 10,000-mile system transports 15% of the natural gas in the ...
Background and origin of the term "pig": In the field, a device that travels inside a pipeline to clean or inspect it is typically known as a pig. PIG is a bacronym for "Pipeline Inspection Gauge". The acronym PIG came later as the nickname for "pig" originated from cleaning pigs (first designed pigs) that sounded like squealing or screeching ...