Back-up power tongs and method

DETAILED DESCRIPTION Referring now to FIG.
1, there may be seen a simplified pictorial side view of apparatus embodying at least one concept of the present invention, and including a suitable rotating power tong assembly 2 disposed about an appropriate location along the length of a joint of drill pipe 4.
In addition, and located immediately below, there is provided a back-up power tong assembly 3 of the type hereinafter described in detail.
The rotating power tong assembly, which operates to apply rotational torque to the length of drill pipe 4, is preferably provided with a plurality of support rods 5 which, in turn, extend fixedly down in parallel with the drill pipe.
The back-up power tong assembly 3, therefore, will preferably be provided with suitable apertures whereby it may be disposed about these support rods 5, to provide for a minimum gap 14 or spacing between the rotating power tongs 2 and the back-up power tong assembly 3.
At the lower end of each of the support rods 5, there is preferably provided a plurality of suitably spaced-apart apertures through which a shear pin 6 may be inserted.
Between the shear pin 6, and the back-up power tong assembly 3, there is preferably provided a suitable washer 9 or other appropriate retaining means, and a suitable spring means 7, whereby the back-up power tong assembly 3 is supported in close proximity to the underneath surface of the rotating power tong assembly 2.
Referring again to FIG.
1, it may be seen that the back-up power tong assembly 3 is preferably provided with a rearwardly extended bracket 11 which supports an appropriate torque sensor 10.
In addition, the rotating power tong assembly 2 is also provided with an appropriate bracket 12 which extends down to drive laterally and rotatably against the torque sensor 10 whenever the rotating power tong assembly 2 is actuated to apply rotational force or torque to the joint of drill pipe 4.
Since the back-up power tong assembly 3 is designed to immobilize the length of drill pipe 4, each of these brackets 10 and 12 tend to be driven together, to not only cooperatively snub both the rotating power tong assembly 2 and the back-up power tong assembly 3, whereby they do not revolve dangerously about, but whereby they cause the torque sensor 10 to provide an appropriate indication of the amount of torque being applied therebetween, (and also consequently to the length of drill pipe 4)