page_title: Pigging
section_title: Intelligent pig
hierarchical_section_title: Pigging / Types of Pigs / Intelligent pig
caption_attribution_description: English: Inserting a pig into a natural gas pipeline in northern British Columbia, Canada.
context_page_description: In pipeline transportation, pigging is the practice of using pipeline inspection gauges, devices generally referred to as pigs or scrapers, to perform various maintenance operations. This is done without stopping the flow of the product in the pipeline.
  These operations include but are not limited to cleaning and inspecting the pipeline. This is accomplished by inserting the pig into a "pig launcher" — an oversized section in the pipeline, reducing to the normal diameter. The launching station is then closed and the pressure-driven flow of the product in the pipeline is used to push the pig along down the pipe until it reaches the receiving trap — the "pig catcher".
context_section_description: Modern intelligent or "smart" pigs are highly sophisticated instruments that include electronics and sensors that collect various forms of data during their trip through the pipeline. They vary in technology and complexity depending on the intended use and the manufacturer.
  The electronics are sealed to prevent leakage of the pipeline product into the electronics since products can range from being highly basic to highly acidic and can be of extremely high pressure and temperature. Many pigs use specific materials according to the product in the pipeline. Power for the electronics is typically provided by onboard batteries which are also sealed. Data recording may be by various means ranging from analog tape, digital tape, or solid-state memory in more modern units.
  The technology used varies by the service required and the design of the pig; each pigging service provider may have unique and proprietary technologies to accomplish the service. Surface pitting and corrosion, as well as cracks and weld defects in steel/ferrous pipelines are often detected using magnetic flux leakage (MFL) pigs. Other "smart" pigs use electromagnetic acoustic transducers to detect pipe defects. Caliper pigs can measure the roundness of the pipeline to determine areas of crushing or other deformations. Some smart pigs use a combination of technologies, such as providing MFL and caliper functions in a single tool. Trials of pigs using acoustic resonance technology have been reported.
  During the pigging run the pig is unable to directly communicate with the outside world due to the distance underground or underwater and/or the materials that the pipe is made of. For example, steel pipelines effectively prevent any significant radio communications outside the pipe. It is therefore necessary that the pig use internal means to record its own movement during the trip. This may be done by odometers, gyroscope-assisted tilt sensors and other technologies. The pig records this positional data so that the distance it moves along with any bends can be interpreted later to determine the exact path taken.
caption: Inserting a pig into a natural gas pipeline
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