Pipeline & Vessel Closures

One of the most critical operations in pigging is opening the closure, which provides access to the pig trap during both launch and recovery operations. When the closure door is opened during the insertion or removal of a pig, there is a risk of explosive gas-air mixture.

For more than 50 years, TDW has manufactured closures designed to save time and improve safety when a pipeline or vessel is opened or closed.

Both the D2000 quick-actuating closures and D500 threaded closures can be operated onshore or on topside platforms in fluids, including natural gas, petroleum products, water, and crude oil.  The D2000 quick-actuating closures – which can be opened by a single operator in less than 1 minute – are sized for pipelines 4 inches and up. The D500 threaded closures are available in sizes from 2 inches through 14 inches.

Best used for: pig traps, filters, strainers, scrubbers, heat exchangers, blowdowns, and other vessels

Key features:

  • An O-ring that won’t open or leak even under low pressure provides a positive seal.
  • The O-ring protects against damage by tools, pigs, or debris.
  • Pressure warning locks provide multiple safeguards.
  • Pressure warning devices alert the operator to the presence of internal pressure before opening the closure.


  • Besides size, how do I determine which closure I need? For repeated and quick access, the D2000 closure is recommended for its quick-actuating features. The D500 threaded closure may be preferred in smaller lines, and when less frequent access is needed.
  • What type of maintenance is associated with pipeline closures? Regular cleaning and greasing of the O-rings, sealing surfaces, and hinges is required. TDW provides a maintenance kit upon request that helps with general maintenance of the closure, ensuring smooth operation over years of use. 

D-500 Threaded Closure

Sized for pipelines from 2 inches through 14 inches, the D-500 threaded closure provides access to pressurized pipelines and vessels in three configurations – hingeless, vertical hinge, and horizontal hinge – for fast, easy, and safe operation. The simple design of the D-500 threaded closure makes it reliable yet economical.

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D2000 Quick-actuating Closure

Available in sizes 4 inches and up, the D2000 Quick-actuating closure features an easy-to-operate clamp ring that can be opened or closed quickly by a single operator. Available in both horizontal and vertical configurations, the D2000 Quick-actuating closure design allows operators to be safely positioned to the side of the closure during opening or closing.

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