The tree cap plug uses a pressure energizing O-ring seal to isolate wellbore fluids. The plug and seal are provided in a variety of materials as required by service conditions. Plugs are retained in place by a tree cap nut which uses course ACME threads for ease of operation.

WH tree caps are available in nominal flange sizes from 2 1/16" to 4 1/16" and pressure ratings from 2,000 to 5,000 psi. A lifting thread is provided in the tree cap body for convenient removal of christmas tree assemblies or for connecting a threaded lubricator. Lifting threads are API upset tubing but available in premium threads when required. The tree cap nut is provided with hammer lugs for easy operation.

WP tree caps are available in nominal flange sizes from 1 13/16" to 4 1/16" and pressure ratings of 10,000 and 15,000 psi. Due to limitations in the rated working pressure of API threads these units are not provided standard with internal threaded connections. Adapters for attaching lubricators to external ACME threads are available. The tree cap nut in the WP is provided with a knurled outer surface to allow for makeup and breaking with torque tools or pipe wrenches. This provides the operator with greater control for safe operation in high pressure or critical service applications.