THREADED JOINT FOR OIL PIPES

摘要

A box member and a pin member each have a tapered thread, an abutment end face and a shoulder for engagement respectively with shoulder and end face of the other member, one coacting surface pair being conical, the other one being planar. Shoulder and end face are spaced differently in the two members such that upon engagement of a conical shoulder and end face, planar end face and shoulder have a gap of about 0.5 to 2.5 per cent of the spacing. Taper/bulge seals are provided adjacent the abutment surfaces to be effective before the planar surfaces abut as the joint is made up. The effective pitch diameter of the pin member remains consistently smaller than the pitch diameter of the box member, at least up to an insertion of the pin member so that the planar surfaces abut.