For SSSV (sub-surface safety valve)
A safety valve is a valve that acts as the protector of your equipment. Safety valves can prevent damage to your pressure vessels and even prevent explosions at your facility when installed in pressure vessels.
A safety valve is a type of valve that automatically actuates when the pressure of the inlet side of the valve increases to a predetermined pressure, to open the valve disc and discharge the fluid. The safety valve system is designed to be a fail-safe so that a wellbore can be isolated in the event of any system failure or damage to the surface production-control facilities.
In most cases, it is mandatory to have a means of closure for all wells capable of natural flow to the surface. The installation of a subsurface safety valve (SSSV) will provide this emergency closure capability. Safety systems may be operated on a fail-safe principle from a control panel located on the surface.