Pressure relieved thread connection

Abstract

Lubricant escape passages are formed in the threads used to connect one tubular body to another. The passages conduct trapped thread lubricant out of the threaded area to prevent the creation of high lubricant pressure that may damage or cause improper make up of the threaded connection. The passages may be grooves in the crests of the thread teeth and/or may be corner bevels on the thread teeth. In a conductor pipe or other pipe assembly using axially spaced internal and external seals at each axial end of the threaded area, the escape passages form a helical flow path through the engaged thread area. The external seal prevents the entry of corrosive fluids into the threaded area and the internal seal prevents leakage through the threaded area from within the conductor pipe. When the lubricant pressure increases excessively during assembly or impact loading of the connection, the lubricant escapes past the seals to prevent connection damage. When used with a wedge or other metal-to-metal thread engaging designs, the escape passages may be interrupted at some point intermediate their helical path to provide a pressure seal at the point of interruption. Relieving trapped lubricant from a wedge thread connection permits consistent final makeup positions that ensure optimal pressure sealing.