STEEL PIPE THREADED JOINT Russian patent published in 2017 - IPC F16L15/04 

FIELD: construction.

SUBSTANCE: bearing face (15) in the male threaded section (11) of the nipple (10) and the supporting faces (24) in the female threaded section (21) of the coupling (20) have an angle θ of slope is less than 0 degrees. The female threaded section (21) is divided in order from the vicinity of the sealing surface (26) to the imperfect thread section (21b) and the full thread section (21a). In the female threaded section (21) in the entire region including the two thread sections (21a, 21b), the throats (23) together form one narrowed periphery. The imperfect thread section (21b) has a length equal to at least a three-fold thread pitch and has a thread height lower than the thread height of the full thread section (21a). In the assembled state, the surfaces (17, 27) of the shoulders are in contact with each other, the sealing surfaces (16, 26) are in contact with each other and the imperfect thread section (21b) between the valleys (13) of the male threaded section (11) and the peaks (22) of the female threaded section (21) are provided with gaps.

EFFECT: sealing characteristic of the external pressure is maintained and the sealing characteristic of the internal pressure is improved.

8 cl, 12 dwg