| 摘要 |
A tong assembly comprising a power tong and a backup assembly. The backup assembly comprises a pair of rotating jaws, each of which carries a jaw die which is rotated into and out of engagement with a tubular being gripped by the backup. The jaw die has a base portion and a gripping surface portion. The gripping surface portion has a profile shape, the profile shape being non-symmetric around a center line through the base portion and normal to the base portion. The non-symmetric profile shape permits an increased range of tubular diameters to be gripped by the backup.
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