Description

What Are Pig Trap Closures?

Pig trap closures are quick opening closures mounted on the ends of pig launchers and receivers. They provide safe, fast access to the pressure vessel for pig insertion and retrieval. A pig trap—also called a pig launcher or receiver—cleans, inspects, or batches pipeline product as it moves through the line. The closure seals the trap end under full operating pressure. Therefore, it must open and close quickly without special tooling.

EMT designs pig trap closures to ASME standards with NACE MR 0175 materials. Our closures handle oil, gas, and water service from -50°C to 300°C. In short, they keep pigging operations safe while cutting downtime. Every unit is welded to the trap neck, then hydrostatically tested before shipment. As a result, you receive a verified, field-ready closure. Pipeline operators use them on crude oil, refined product, gas, and water lines worldwide.

How Do Pig Trap Closures Work?

Pig trap closures rely on a locking mechanism to hold the head cover against line pressure. The lock-ring (Bandlock) type uses a spring-loaded band that expands into a groove on the barrel flange. A safety screw with a relief groove vents any residual pressure before the cover moves. This two-step release prevents accidental opening. A single elastomer seal in the groove keeps the joint leak-tight through many cycles.

Closures come in three structure types: bayonet, clamp, and lock-ring. Bayonet units fit DN100–DN350 pipelines and are simple to operate. Clamp units use a segmented ring on horizontal or vertical traps. Lock-ring units suit DN400–DN1200 lines and need less force, so one person can open them.

Additionally, every type is available in horizontal and vertical versions. Horizontal units install truly level with only 0–5 mm saddle offset. For pig trap closures, we match the type to your trap diameter, pressure, and layout. This ensures repeatable, safe operation.

Key Features and Benefits

• Fast access— Open and close the trap in minutes, not hours.
• Safe locking— Band lock, safety screw, and relief groove stop accidental opening under pressure.
• Wide material range— 16Mn, A350 LF2, A105, SS304/316, F51/F53/F55 duplex, INCONEL 625, HASTELLOY C.
• High rating— Design pressure to 40 MPa; design temperature -50°C to 300°C.
• Sour-service ready— NACE MR 0175 materials resist H₂S and CO₂ environments.
• Low maintenance— Single seal groove with a 12-month service interval.

These features reduce downtime and extend asset life on critical pipeline systems. Moreover, the simple handle operation removes the need for heavy lifting gear.

Technical Specifications

Parameter	Range / Option
Nominal diameter (DN)	< 1800 mm
Design pressure (PN)	< 40 MPa
Design temperature	-50°C – 300°C
Working medium	Oil, gas, water
Pipe wall thickness	6 – 100 mm
Materials	16Mn, A350 LF2, A105, SS304/316, F51/F53/F55, INCONEL 625, HASTELLOY C
Structure types	Bayonet, Clamp, Lock-Ring (Horizontal / Vertical)
Standards	ASME B16.5, NACE MR 0175

EMT also supplies complete pig launcher and receiver skids. Design pressure reaches 42 MPa with a 2 mm corrosion allowance and 7-degree seismic rating. The closure is the access point at the trap end, so we size it to match your barrel and piping class. Because materials and wall thickness are selectable, the same closure family serves sweet and sour service alike. We also offer spare seal kits and on-site alignment service.

FAQ

What are pig trap closures used for?

They seal the end of a pig launcher or receiver. Operators open them to load or remove pipeline pigs during cleaning, inspection, and batching runs.

How do I choose the right type?

Use bayonet for DN100–DN350. Choose lock-ring (Bandlock) for DN400–DN1200. We confirm the best type after reviewing your trap size, pressure, and orientation.

Are EMT closures NACE compliant?

Yes. We supply NACE MR 0175 materials for sour gas and oil service on request, including duplex and nickel alloys.

Can one person operate the closure?

Yes. Lock-ring closures open with a handle and need low force. However, always vent and drain the trap fully before opening.

Do you provide the full pig trap?

Yes. We deliver pig launchers, receivers, and closures as integrated skids, with pressure gauges, vents, and drains included.