THREADED JOINT FOR STEEL PIPES

摘要

A threaded joint for steel pipes comprising a pin (1) and a box (2). The pin has a male thread (11) and a lip (12) which comprises (i) a sealing surface (13) and (ii) a nose portion (16) provided with a shoulder surface. The box has a female thread (21), a sealing surface (23) and a shoulder surface. The shoulder surface of the pin comprises two distinct adjacent surfaces, main shoulder (14) in the inner side and sub shoulder (15) in the outer side. Correspondingly, the shoulder surface of the box comprises two distinct adjacent surfaces, main shoulder (24) in the inner side and sub shoulder (25) in the outer side. The main shoulder surfaces of the pin and box are disposed such as to prevent a radially inward deformation of the lip end, and the sub shoulder surfaces of pin and box are disposed such as to limit a radially outward deformation of the lip end. The main shoulder of the pin has a greater radial dimension than said sub shoulder of the pin, and at least the main shoulder surface of the pin is in axial abutment with at least the corresponding main shoulder surface of the box.