The casing head is mainly composed of components such as the bottom casing head, casing hanger, casing head spool, and valve.

The sealing of the casing head consists of the casing head body, BT shaped rubber sealing ring, casing hanger, dovetail shaped rubber sealing ring, top thread V-shaped sealing ring, and sealing gasket ring.

The casing hanger seat is hung on the steps of the casing head body, and due to the suspended weight of the casing, the contact between metal and metal generates a rigid passive seal. The seal between the casing hanger and the casing is a threaded seal.

The casing head four way has a BT seal that matches the outer diameter of the casing hanger (or casing outer diameter) and corresponding grease injection and pressure testing holes. During use, high-pressure sealing grease must be injected from the grease injection valve to make the BT seal effective.

If there is leakage in the seal, sealing grease should be injected into the grease injection valve and pressure testing valve respectively to ensure that the seal continues to take effect.

The grease injection pressure shall not exceed the rated working pressure of the flange; If the casing is sealed, it shall not exceed the rated allowable collapse pressure of the casing.

The pressure test hole is used for the external sealing test of the casing hanger.

There is a top screw on the flange used to lock the anti wear sleeve (protecting the sealing surface), which can be locked after the casing hanger is installed.

If there is leakage at the top thread, the pressure cap can be tightened to make the sealing effective. The flange on both sides of the casing head four-way is connected, with one end connected to a flat valve (or blind flange), and the other end connected to a flat valve, threaded flange, joint, stop valve, and pressure gauge. The annular pressure between the two casing layers can be observed through the pressure gauge.