drill collar

基本解释

While installing or removing the drill collar clamp, hold weight of string with block.
任何时候都不能挡住司钻看井口钻杆的视线。
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Main reasons of causing drill collar screw failure are discovered by way of further investigation and analysis on these problems.
通过对钻铤螺纹失效问题的深入调查和分析，找出引起钻铤螺纹失效的主要原因。
Do not make up or break out the bit on a single joint of DC. If this is absolutely necessary, always snub drill collar with the air tugger.
不要在一单根钻铤上卸钻头，如果确实需要这样做，要用气动绞车拉住钻铤。
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