Wellhead Valve Operating Precautions

The valves must be operated carefully when opening or closing. Some valve types have a shear pin between the handle and stem, which will shear to protect the valve’s internal components, if excessive force is applied. The master valve should not be used to close in a flowing well, except in an emergency. The swab or wing valves are typically used. Each time the gates of the valve shut in a flowing well, the increase in velocity of the well fluids during the closing action can cause wear across the seal faces. It is easier and safer to replace the seats and gates in valves, other than the master valve in the tree. Always count the number of valve turns made when closing. This is a prudent check against jamming the toolstring or wire in the tree, in the event that the tools have been raised fully into the lubricator.

source: aqemachinery.com

Tubing Hanger

The tubing hanger is the device that supports the production tubing within the tubing head. A seal assembly on the body of the tubing hanger provides a hydraulic seal between the tubing hanger and the body of the tubing head. Tubing hangers, in most circumstances, are designed with an extended neck which seals in the bottom of the adapter flange to isolate the well fluids from the tubing head ring joint seal.

Internal profiles on the tubing hanger provide a means for inserting a tubing back-pressure valve (BPV). The body of the tubing hanger is ported for the routing of a small control line that is connected to the sub-surface ball valve. The threaded connections top and bottom of the tubing hanger are compatible with the tubing string being suspended. In the lifetime of the wellhead, the tubing hanger is the component that will most commonly be removed and replaced.