| 主权项 |
1. A dual drill pipe joint, comprising:
a joint of drill pipe having a pin end and a box end; a one-piece inner pipe disposed within an internal bore of the joint of drill pipe; a retainer disposed proximate each longitudinal end of the inner pipe; a retaining feature formed in an interior of the joint of drill pipe proximate each longitudinal end, the retaining features configured to engage a respective one of the retainers so that the inner pipe is held in longitudinally fixed relation to the joint of drill pipe, at least one of the retainers removably affixable to the inner tube as the inner tube is placed in tension; and a plurality of longitudinally spaced apart standoffs disposed on an exterior surface of the inner tube, each standoff having a standoff dimension urging the inner tube out of axial alignment with the joint of drill pipe. |
