The casing head is used mainly to fix wellhead, connect downhole casing string and reliably seal and control inter-pipe annulus. The casing head is important equipment of the oil (gas) production wellhead equipment of oilfields. The pressure grade of the casing head is 2000Psi~20000Psi(14MPa~140MPa) and its material grade AA~HH.

The casing head can be divided into integral casing head and split casing head in terms of casing head body and into spindle casing head and slip casing head in terms of casing hanger structure. The hangers of the two structures are of interchangeability. The casing hanger has two main sealing modes such as rubber sealing and metal sealing. Casing and casing hanger has two secondary sealing modes including rubber sealing and metal sealing.