초록 ▼

A power tong 10 for making up and breaking apart threaded oilfield tubular connections includes a frame 11 having an open throat 20, a rotary ring 16 having an open throat 22, and a door 24 for closing over the open throat for safety. Hydraulic motor 42 is regulated by a control valve 52 for rotatin

A power tong 10 for making up and breaking apart threaded oilfield tubular connections includes a frame 11 having an open throat 20, a rotary ring 16 having an open throat 22, and a door 24 for closing over the open throat for safety. Hydraulic motor 42 is regulated by a control valve 52 for rotating the ring 16 which in turn rotates the oilfield tubular. A switch 46 responsive to the position of the door 24 controls the flow of air pressure to a cylinder 50, which renders active valve operator 54 which controls valve 52. According to the method of the invention, the door 24 must first be closed so that the switch 46 renders the valve operator 52 active, and the valve operator 52 must be reset once the door is opened before it can be manipulated to operate the motor control valve 52.

대표청구항 ▼

1. A safety system for controlling operation of a power tong used to make up and break apart a threaded oilfield tubular connection, the power tong including a tong frame having a frame open throat, a rotary ring rotatably supported on the tong frame and having a ring open throat, a door supported o

1. A safety system for controlling operation of a power tong used to make up and break apart a threaded oilfield tubular connection, the power tong including a tong frame having a frame open throat, a rotary ring rotatably supported on the tong frame and having a ring open throat, a door supported on the tong frame for opening to laterally move the power tong on and off the oilfield tubular connection and for closing over the frame open throat when the oilfield tubular connection is within the rotary ring, and a hydraulic motor supported on the tong frame for rotating the rotary ring, the safety system comprising:a motor control valve operable to control flow of pressurized fluid from a hydraulic power source to the hydraulic motor; a switch supported on the tong frame for outputting a signal in response to the position of the door with respect to the tong frame; a valve operator for controlling operation of the motor control valve; a fluid pressure responsive member for automatically engaging and disengaging operation of the valve operator and thus the motor control valve, the fluid pressure responsive member being biased for disengaging operation of the motor control valve: and a safety control line for interconnecting to the switch and the fluid pressure responsive member, such that the switch engages operation of the valve operator by transmitting a closed door signal to the valve operator when the door is closed, and the switch disengages operation of the valve operator by transmitting an open door signal to the valve operator when the door is open.