BOPI 05 BR/2023 REPERTOIRE NUMERIQUE 20 Consulter le mémoire ________________________________________ (11) 20943 (51) F16L 15/04 (2018.01) (21) 1202100543 - PCT/JP2020/030407 (22) 07/08/2020 (30) JP n° 2019-147926 du 09/08/2019 (54) Threaded coupling for steel pipe. (72) SUGINO, Masaaki (JP); INOSE, Keita (JP); UGAI, Shin (JP) et NAKANO, Hikari (JP) (73) 1- Nippon Steel Corporation, 6-1, Marunouchi 2-chome, Chiyoda-ku, TOKYO 1008071 (JP) et 2- Vallourec Oil And Gas France, 54 rue Anatole France, AULNOYE-AYMERIES 59620 (FR) (74) SPOOR & FISHER Inc. NGWAFOR & PARTNERS Sarl, The House of Gideon, Golf/Bastos Quarters, Opposite The American Embassy, Entrance-Saint John Paul II Boulevard, P.O. Box 8211, YAOUNDE (CM). (57) An object of the present disclosure is to ensure good sealability in a threaded connection for steel pipe of a two-step thread construction including an intermediate seal and intermediate shoulders. The pin 2 includes an intermediate seal section 22, an inner male-threaded section 23, an intermediate shoulder 24, an intermediate seal section 25 and an outer male-threaded section 26. The box 3 includes an intermediate seal section 32, an inner female-threaded section 33, an intermediate shoulder 34, an intermediate seal section 35 and an outer female-threaded section 36. The pin 2 has a pin intermediate critical cross section PICCS located near an end of the first male-threaded section23. The box 3 has a box critical cross section BCCS located near an end of the first female-threaded section 33 and a box intermediate critical cross section BICCS located near an end of the second female-threaded section 36. The pin 2 and the box 3 satisfy the following relationships: PICCSA + BICCSA > BCCSA, and 0.70 < PICCSA/BICCSA < 0.95.
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