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1·When picking up or setting down drill collar stands larger than 6 1/4 on the floor board, always snub with the air tugger.

当在钻杆盒上提起或放置直径大于6 1／4〞的钻铤立柱时，一定要用气动绞车拉住以保安全。

2·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。