What Is Pipeline Pigging and Why It Matters
Pipeline pigging uses devices called pigs to perform maintenance operations inside pipelines without stopping flow. Pigs clean deposits, separate products in batch transfer, inspect pipe wall integrity, apply coatings, and dewater pipelines.
Pig Launcher and Receiver Design
Launcher components: Main barrel (1.25-1.5x pipeline ID), quick-opening closure, kick-off valve, pig signal transmitter, vent and drain connections, bypass line.
Receiver: Similar design with larger debris collection section. Both must comply with ASME VIII Div.1.
Types of Pigs
Cleaning Pigs: Foam pigs (gentle), steel body scrapers (hard deposits), brush pigs (soft debris), magnetic pigs (ferrous debris).
Batching/Separation Pigs: Cup pigs, sphere pigs, disc pigs for product separation.
Intelligent Pigs (ILI): MFL (magnetic flux leakage), UT (ultrasonic), UT-C (crack detection), caliper (geometry), inertial mapping.
Operational Procedures
Pre-Launch Checklist: Verify pipeline conditions, inspect pig, check isolation valves, confirm communication, check tracking equipment.
Launch Steps: Isolate barrel -> Open bypass -> Depressurize -> Open closure -> Insert pig -> Close and secure -> Equalize pressure -> Open kick-off valve -> Verify pig departure.
Pig Velocity Control
| Pig Type | Ideal Velocity (Liquid) | Ideal Velocity (Gas) |
|---|---|---|
| Cleaning pigs | 2-5 m/s | 4-18 m/s |
| Intelligent pigs (MFL) | 0.5-2.5 m/s | 0.5-2.5 m/s |
| Intelligent pigs (UT) | 0.5-2.0 m/s | 0.5-2.0 m/s |
Safety Requirements
- Never open closure under pressure – verify zero pressure
- Use gas detectors for H2S and hydrocarbons
- SCBA available at work site for sour gas service
- Never stand in front of open barrel during pressurization
- Contain all barrel contents during pig removal
Sourcing Pigging Equipment
CoreMetal Steel supplies carbon steel, stainless steel, and alloy steel pipe, fittings, and flanges for pig launcher and receiver systems per API, ASTM, and ASME standards.
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