Abstract: A threaded pipe connection is disclosed comprising a box having internal threads and a pin having external threads for mating with the internal threads of the box. The mating threads exert radial forces on the box and pin creating compressive hoop stress in the pin and tensile hoop stress in the box. A conical sealing surface on the pin between the threads and the end of the pin engages conical sealing surface on the box and forms a metal-to-metal seal when the connection is made up. Means are provided for reducing the radial forces exerted by the threads adjacent the conical sealing surfaces to reduce excessive metal-to-metal contact bearing stress and better distribute the remaining stress in the engaging sealing surfaces while maintaining the contact stress required to provide an adequate seal.

Abstract: The same size and weight of tubular products, but in different grades of material, are made for universal connection but with seal areas that differ appropriately for adequate sealing without overstressing the connection members for the pressures encountered where each tubular length is put in service. The angle of the conically tapered seal on all box members is made the same for all grades of the products. The pin member of medium grade is made with an equal length seal area and adjacent contracting area on its forward end. The pin member of lower grade is made with a shorter length seal area than its adjacent contacting area, thereby also placing the seal area further from the pin member distal end. This stiffens the pin member. The pin member of higher grade is made with a longer length seal area than its adjacent contacting area.

Abstract: A tubular connection having a nose extension on the pin member for stiffening the member and exhancing the conical seal area forward of the first thread, which seal is spaced at a distance from the time end by a non-sealing nose extension that is at least as long as the sealing area. The integrity of the seal is improved, the bearing surface is enlarged and the tendency of galling is reduced.

Abstract: 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.