A pig launcher is a pressurized barrel assembly used to insert pipeline pigs into a live pipeline. A pig receiver is the corresponding barrel at the other end of the pipeline that captures and removes the pig after it has traveled through the line. Together, they form the pigging system that allows pipeline operators to clean, inspect, and maintain pipelines without shutting down flow.
Pipeline pigs are cylindrical devices pushed through the pipeline by the flowing product. The term “pig” originally referred to the squealing sound early devices made inside the pipe; it is also used as an acronym for Pipeline Inspection Gauge.
Pig Launcher and Receiver Components
Component Launcher Receiver Barrel Oversized pipe (1.5-2x pipeline diameter) for pig loading Same design for pig retrieval Closure (door) Quick-opening or bolted closure (front) Quick-opening closure (front) Reducer Barrel to pipeline reducer (eccentric, flat bottom) Pipeline to barrel reducer Mainline valve Isolates barrel from pipeline Isolates barrel from pipeline Bypass valve Allows flow to bypass barrel Allows flow to bypass barrel Kicker line Supplies flow behind pig to launch Vents/drains receiver barrel Drain valve Drains barrel before opening Drains barrel before opening Vent valve Depressurizes barrel Depressurizes barrel Pig signaler Detects pig passage (downstream) Detects pig arrival Pressure indicator Monitors barrel pressure Monitors barrel pressure
Types of Pipeline Pigs
Pig Type Function Design Utility pig (foam) Dewatering, drying, light cleaning Foam cylinder, various densities Mandrel pig Cleaning, scraping, batching Metal body with polyurethane cups/discs Brush pig Heavy cleaning, wax removal Wire brushes on mandrel body Bi-directional pig Cleaning in both directions Symmetrical cup design Batching pig Separates product batches Tight-sealing cups, low bypass Gel pig Cleaning, dewatering Viscous gel slug (no hardware) Smart pig (ILI tool) Inline inspection (MFL, UT, caliper) Instrumented tool with sensors and data recorder Caliper pig Measures ID and detects dents/ovality Mechanical fingers or electromagnetic sensors
Pigging Operations
Operation Pig Used Purpose Pre-commissioning Foam, mandrel Remove debris, dewater after hydrostatic test Routine cleaning Mandrel, brush Remove wax, scale, deposits Batch separation Batching pig Separate different products in multi-product lines Inline inspection (ILI) Smart pig Detect corrosion, cracks, dents, coating loss Chemical treatment Gel pig Apply inhibitor or biocide to pipe wall Gauging Caliper pig Verify minimum bore before smart pig run
Piggability Requirements
For a pipeline to be piggable, several design requirements must be met:
Requirement Standard Practice Minimum bend radius 3D (absolute minimum), 5D preferred for smart pigs Consistent bore No internal restrictions (protruding welds, reduced-bore valves) Valve type Full-bore ball valves or gate valves Tee junctions Barred tees (with pig deflector bar) Check valves Full-bore, swing-type (pig-passable) Pipe bends Hot induction bends (5D radius standard)Pipeline ovality < 3% for smart pig passage
Design the pig launcher and receiver at the FEED stage, not as an afterthought. Retrofitting a pig launcher/receiver onto an existing pipeline is significantly more expensive and may require a hot tap connection. The launcher/receiver barrel length must accommodate the longest pig to be used, including smart pigs which can be 3-5 meters long. Allow space for a crane or forklift to handle the pig at each location.
Applications
Oil and gas transmission pipelines (cleaning and ILI)
Multi-product pipelines (batch separation)
Subsea pipelines (wax management)
Gas pipelines (liquid removal, corrosion inhibitor application)
Water pipelines (biofilm and scale cleaning)
Pre-commissioning of new pipelines (flooding, cleaning, pressure testing )
Read the full guide to pipe types
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