This invention relates in general to drill pipe handling apparatus used in oil and gas drilling rigs and, more specifically, to an improved bridge coupler for drill pipe and an actuator therefor.
A wide variety of devices have been used for handling and interconnecting drill pipe in oil and gas drilling rigs over the years. Connections between lengths of pipe must be capable of being made and broken rapidly, positively and safely. The threaded connections between the conventionally threaded pipe ends and a pipe coupler must be made to a high level of torque and must be protected against accidental separation due to the effects of pipe string rotation, vibration and the like. The conventional kelly spinner system used to thread pipe to couplers does not provide the high level of torque required today for direct threaded connections.
Modern high efficiency drilling equipment requires improved couplings. Top drive assemblies of the sort shown in U.S. Pat. No. 4,421,179 and side drive type assemblies of the sort shown in U.S. Pat. 4,875,529 both impart considerable torque to the drive string. These drilling systems permit an operator to drill with a triple stand of pipe, rather than a single stand as with a conventional kelly bushing drill rig. These systems permit a driller to ream the hole as the pipe string is pulling out of, or running into, the hole. During such reaming, the driller rotates the pipe string. This imparts significant torque to the couplings.
When reaming out of the hole, the top connection of each triple stand is broken out high in the derrick, while when running into the hole the top connection must also be made high in the derrick. This requires the make up and break out equipment to be located towards the top of the derrick. Complex or bulky make and break devices, or those requiring high torque, are inconvenient and difficult to provide at that location.
Attempts have been made to provide lower torque couplings for these situations, such as that shown in U.S. Pat. No. 4,658,915. While providing some benefit, these couplings still require substantial torque and do not fully provide effective locking of the made up connection against accidental separation due to vibration or the like. The actuator systems for these couplings is often complex, difficulty to operate and may not provide the required connection reliability.
Thus, there is a continuing need for compact, reliable, pipe coupling systems requiring less torque for making up and breaking connections and providing more reliable connections.