Patent ID: 8439121

Claim:
A drilling rig system for connecting pipe, comprising: a first tool having slips that are hydraulically actuated to move the slips between a released position and a gripping position in gripping engagement with a first pipe; a second tool having gripping members that are hydraulically actuated to move between a released position and a gripping position in gripping engagement with a second pipe member for connection to the first pipe; a manually operable first tool control valve having an apply position to direct apply hydraulic fluid pressure to move the slips to the gripping position and having a release position to direct release hydraulic fluid pressure to move the slips to the released position; a manually operable second tool control valve having an apply position to direct apply hydraulic fluid pressure to move the gripping members to the gripping position and having a release position to direct release hydraulic fluid pressure to move the gripping members to the released position; a hydraulic safety circuit that senses apply hydraulic fluid pressure at the second tool and prevents hydraulic fluid pressure from being directed to move the slips to the released position if apply hydraulic fluid pressure is not already being directed to hold the gripping members in the gripping position; and the safety circuit also senses apply hydraulic fluid pressure at the first tool and prevents release hydraulic fluid pressure from being directed to move the gripping members to the released position if apply hydraulic fluid pressure is not already being directed to hold the slips in the gripping position.