Drilling safety valves include Kelly Valves, Inside BOP Valves, and Retrievable Drop-In Check Valves (RDCV):
The Kelly Valve, also called Full Opening Safety Valve (FOSV), can be used as a drill pipe safety valve, Upper Kelly Valve, or Lower Kelly Valve.
- Upper Kelly, the valve can be used to control blowout pressures by shutting off flow in the drill string at any time
- Lower Kelly, the valve can stop mud loss when the Kelly is disconnected from the drill string.
The IBOP, also called Gray Valve or BVR, is a back pressure valve used in the drill string to prevent the well from flowing uncontrollably up the drill string. It is generally used 2 ways:
- On the rig floor with a complete IBOP configuration.
- Below the rig floor without a plug when connected in the drill-string. It can be left in the drill string as long as necessary to re-establish control of the well-pressure balance.
The RDCV, also called Dart Valve or a Back-Pressure Valve, controls back flow through the drill pipe during a kick or when tripping pipe into the hole against pressure. Check-valve compatibility should be checked with Kelly Cock free passage.