Importance

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Abstract

A back-up tong for use with a power tong holds the lower pipe in a pipe joint from being rotated, so as to effect makeup or breakout of the pipe joint. The backup tong employs sliding heads which are driven by camming surfaces on a ring-like member fixedly positioned about the pipe, when the heads are arcuately rotated about the pipe. The assembly holding the heads is arranged to be released automatically from the bottom of the back-up tong frame, in the event that the drill string begins to slip back down into the hole, or in the event a portion of the string is prematurely lifted, thereby preventing damage to the back-up tong. The back-up tong is constructed so that only a minimum amount of clearance is required at the top working surface, thereby permitting the sliding heads to be located as near the joint as possible when simultaneously using a power tong.

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First Claim