| 摘要 |
A tubular connection is disclosed having a small diameter thread set and a large diameter thread set, the small thread set having a lesser number of threads than the large set. A primary torque shoulder is located between the threads sets and a secondary torque shoulder is located behind the large thread set. In the preferred embodiment, the initial partial thread on the pin of both sets and the last partial thread of the small set on the box has a cylindrical root contour, whereas the remainder of the threads are tapered. The longitudinal taper angle of the pin thread sets are dissimilar to the box thread sets, there being a maximum separation of the sets near the center of the connection. Such dissimilar tapering tends to equalize the stress applied to the threads under tension loading. At the center, a seal is provided with hooked threads on either side thereof. The arrangement also provides a torque shoulder at either end of the large thread set. The arrangement provides in a tapered connection having two thread sets of difference diameters, two torque shoulders and two metal-to-metal seal areas. |
