| 摘要 |
A drill section includes a hollow tube having a reduced portion of a box disposed in each end. Each box is welded to the hollow tube by a circumferential weld extending around an angled portion connecting the reduced portion of the box to a portion of the box having the same outer diameter as the hollow tube. There preferably is welding of the reduced portion of the box to the hollow tube through three equally angularly spaced slots at each end of the hollow tube. A break out ring is disposed on a threaded pin of a tool joint between the box, which has a threaded recess extending inwardly from its end to receive the threaded pin to attach the tool joint to the box, and an annular surface of the tool joint. A protective sleeve on the box has an annular end surface at the same angle to its longitudinal axis as an annular end surface of a collar, which is welded to the box, and held thereagainst by the tool joint attached to the box. One tool joint has a threaded recess, and the other tool joint has a threaded pin, which extends into the threaded recess of the tool joint of the drill section above it while the threaded recess in the tool joint receives the threaded pin of the tool joint of the drill section beneath it or the threaded end of a drill bit sub. |
