TUBULAR JOINT WITH TRAPPED MID-JOINT METAL-TO-METAL SEAL HAVING UNEQUAL TAPERS

摘要

A joint and male and female tubular element are disclosed where the threads of the female and male members have negative load flanks and have two or more radial steps axially separated one from another by a reverse angle torque shoulder having one or two adjacent conical sealing surfaces. The reverse angle torque shoulder produces radial positional interference of the conical sealing surfaces when the male and female members are fully assembled and serves as a positive assembly stop. The negative load flank angle of the threads and the reverse torque shoulder angle combine to interlock the male and female members and to prevent differential radial separation of the conical sealing surfaces when the joint is exposed to internal pressure, external pressure or both. Tapered threads and sealing surfaces and interference threads may advantageously be used in joint construction. Tapered conical sealing surfaces are provided in a preferred embodiment where the taper of the member having the thinner wall thickness at the seal surface is inclined at a smaller angle with respect to the axis of the threaded connection than the complementary conical seal surface of the mating member, may advantageously be used to that the bearing load across the entire axial width of the male and female sealing surfaces has a relatively even distribution at final make-up.