Valves for Pig Launcher / Receiver
A pressure vessel that is deliberately opened while connected to a live pipeline - which makes its valve interlock sequence the most safety-critical part of pigging operations.
Which valves are used on a pig launcher / receiver?
A pig launcher / receiver carries 5 characteristic valve interfaces: mainline isolation, kicker / bypass, trap drain and vent, pressure equalisation, purge (nitrogen). Each position, its usual valve configuration and the engineering reason are below. Typical specs are indicative — line class and project specification govern.
The Valve Interface Map
Mainline isolation
Ball Valves →Full-bore trunnion ball or through-conduit gate
Piggable full-bore isolation between trap and pipeline - API 6D territory by definition.
Kicker / bypass
Ball Valves →Ball valve
Diverts flow to launch the pig; sized against the mainline differential.
Trap drain and vent
Ball Valves →Small-bore ball valves
Depressurise, drain and gas-test the barrel before the closure is opened - the life-safety step.
Frequently interlocked with the closure; vent sizing matters for timely depressurisation.
Pressure equalisation
Ball Valves →Small-bore ball valve
Equalises across the mainline valve before opening it against differential.
Purge (nitrogen)
Ball Valves →Ball valve with check
Inerting the barrel on sour or rich-gas systems before opening.
Isolation Strategy
- The launch/receive sequence is a strict valve order - interlocks or rigorous procedure, never memory
- Closure never opened until vent is proven open, pressure proven zero, and drains confirmed clear
Maintenance Notes
- Mainline valve seat tightness is the barrier between an open trap and a live pipeline - seat-test on schedule
- Vent and drain small-bores are the corrosion victims; inspect as pressure boundaries, not accessories
Governing & Adjacent Standards
Other equipment valve references
Connected Engineering
Sourcing valves for a pig launcher / receiver?
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