Method and device for positioning a power tong at a pipe joint

1. A method of positioning a power tong at a pipe joint of a pipe string, the method comprising:

providing a camera movement assembly for displacing a camera, the camera movement assembly including a guide member oriented substantially in parallel with the pipe string, an actuator and a transducer;

moving the camera independent of the power tong and substantially in parallel with the pipe string along the guide member using the actuator;

stopping the movement of the camera when an image of the pipe joint coincides with a marker in a display;

transmitting a signal via a line from the transducer to a control for the power tong; and

controlling the movement of the power tong to the pipe joint based upon the signal.

2. The method in accordance with claim 1 , wherein the control, which receives information about the relative positions of the camera and the power tong, automatically guides the power tong to the correct position.

3. The method in accordance with claim 1 , further comprising tracking the position of the camera using a second transducer that is coupled to the actuator and is in communication with the control.

4. The method in accordance with claim 3 , further comprising tracking the position of the power tong using a third transducer that is coupled to the power tong and is in communication with the control.

5. The method in accordance with claim 4 , further comprising controlling the movement of the power tong using the control and the tracked position of the camera.

6. The method in accordance with claim 1 , further comprising monitoring an image of the pipe string on the display while moving the camera substantially parallel to a longitudinal axis of the pipe string.

7. The method in accordance with claim 1 , further comprising sending a signal to the control when the image coincides with the marker automatically moving the power tong in response to the signal to the position that corresponds to the location of the pipe joint.

8. The method in accordance with claim 1 , wherein the camera is configured to move while the power tong remains substantially stationary.

9. A positioning device for positioning a power tong at a pipe joint of a pipe string, the positioning device comprising:

a camera that is displaceable independent of the power tong and substantially in parallel with the pipe string, wherein the camera is arranged to be displaced until an image of the pipe joint coincides with a marker in a display;

a camera movement assembly for displacing the camera, the camera movement assembly including a guide member oriented substantially in parallel with the pipe string, an actuator for moving the camera along the guide member and a transducer; and

a control for the power tong connected to the camera movement assembly via a line, the control is arranged to receive a signal from the transducer in the camera movement assembly and control the movement of the power tong to a position that corresponds with that of the pipe joint.

10. The device in accordance with claim 9 , wherein the actuator is an electric motor.

11. The device in accordance with claim 9 , wherein the actuator is a hydraulic cylinder.

12. The device in accordance with claim 9 , wherein the transducer is operable to track the position of the camera.

13. The device in accordance with claim 12 , further comprising a second transducer that is in communication with the control and operable to track the position of the power tong.

14. The device in accordance with claim 9 , wherein the control is configured to automatically move the power tong to a position that corresponds with a location of a pipe joint of the pipe string when the image of the pipe joint is displayed on the display.

15. The device in accordance with claim 9 , wherein the camera is configured to move while the power tong remains substantially stationary.