A Christmas tree mainly equipment with four or five different types of hydraulic valves. Sequential opening and closing of these valves are done by wellhead control panel (WHCP). The valves are,

◎ SCSSV(surface controlled subsea safety valves or Down Hole valve)
◎ SSV(surface safety valves) which consist of the following valves)
◎ Master valves (MV)
◎ Wing valves (WV)

Hydraulic tree valves require active hydraulic pressure to stay open.
Usually WHCP is place about 100 meters away from the well head and the Hydraulic or pneumatic output from the panel is connect to well head through properly size tubes. Types of wellhead control panels:

◎ Pneumatic/hydraulic WHCP
◎ Electro/hydraulic WHCP
◎ Single well WHCP
◎ Modular multi well WHCP
◎ PLC based electro-hydraulic WHCP
◎ Solar power WHCP.