Pigging is the practice of sending a device called a "pig" through the inside of a pipeline, pushed along by the product flow itself. Depending on the pig, the goal is to clean the line, separate different products, remove liquids, or inspect the pipe wall for corrosion and defects. It is one of the primary ways operators keep a pipeline efficient and safe without shutting it down.
Pig / Pigging in one line: Pigging is running a device called a pig through a pipeline - propelled by the flowing product - to clean the line, separate batches, sweep out liquids, or inspect the pipe wall for corrosion and defects.
The term "pig" is often said to come from the squealing noise early units made against the pipe wall. Functionally, pigs fall into a few categories. Utility or cleaning pigs scrape wax, scale, and debris off the wall and sweep accumulated liquids ahead of them, which restores flow efficiency and reduces internal corrosion. Batching or sealing pigs separate two different products moving back-to-back in the same line so they do not mix at the interface. Gauging pigs verify a line is round and free of dents before commissioning.
Smart pigs, or inline inspection (ILI) tools, are the sophisticated end. Packed with sensors, they measure the pipe wall as they travel - magnetic flux leakage (MFL) tools find metal loss from corrosion, ultrasonic tools measure wall thickness, and caliper tools map dents and geometry. The data they log is analyzed afterward to locate and prioritize defects for repair, and is a core part of pipeline integrity management.
A pig is loaded into a pig launcher (a barrel with a valve arrangement) at one end of the line, then isolated and pressured up so the product flow pushes it downstream. It travels at pipeline velocity and is caught at the far end in a pig receiver. Launching and receiving are carefully sequenced operations involving pressurizing, equalizing, and venting the barrel - done wrong they are a safety hazard, so procedures and interlocks matter.
Operators track a pig's progress by watching pressure and flow, and by pig-signalers (passage indicators) mounted along the route that detect the pig going by. SCADA plays a supporting role here: pressure and flow transmitters, launcher and receiver valve and trap-door status, and pig-passage signals can all be brought into the control system so the operator confirms the pig launched, follows its transit, and gets alarmed if it stalls. Those field instruments typically report over Modbus or DNP3, so a cloud SCADA platform can present the whole pig run on one screen.
The most repeated explanation is the squealing, pig-like noise that early cleaning pigs made as their scrapers dragged against the pipe wall. The industry also treats PIG as a backronym for "pipeline inspection gauge," but the equipment and the term predate that tidy expansion.
A smart pig, or inline inspection tool, is a pig loaded with sensors that measure the pipe wall as it travels - typically magnetic flux leakage or ultrasonics to find corrosion and metal loss, plus caliper sensors for dents and geometry. The recorded data is analyzed to locate and rank defects, making smart pigs central to pipeline integrity programs.
Yes, in a supporting role. Pressure and flow transmitters, pig-signaler passage indicators, and launcher/receiver valve and trap status feed into SCADA over protocols like Modbus or DNP3. That lets operators confirm the launch, follow the pig's transit, and get alarmed if it stalls or a trap is left in an unsafe state.
This page references the protocol specifications published by the organizations below. Editions, product capabilities, and documentation change over time - confirm current requirements and specifications directly with the source.
Last reviewed: July 27, 2026. Merobix is not affiliated with, endorsed by, or sponsored by these organizations; their names are used only to identify the standards and products discussed.
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