| 摘要 |
An improved method for protecting a drill pipe casing from a rotatable string of drill pipe longitudinally extended therethrough. The method involves positioning a collar structure circumferentially around the upper end of one pipe section which is internally threaded and then thereafter engaging therewith the lower end of a second pipe section which is externally threaded and engageable with said first pipe section. The collar structure is formed of a poly(arylene sulfide) and is a single unitary structure having circumferentially extended outer surfaces which are adapted to resist spinning with the drill pipe string positioned in the casing structure.
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