BOPI 12 BR/2023 REPERTOIRE NUMERIQUE 45 Figure 1 ________________________________________ (11) 21325 Consulter le mémoire (51) E21B 17/042 (2018.01) (21) 1202300345 - PCT/EP2022/054824 (22) 25/02/2022 (30) EP n° 21159721.6 du 26/02/2021 (54) Coupling for connecting downhole tubulars with reduced stress. (72) JANSSON, Tomas (SE) et NORDBERG, Anders (SE) (73) SANDVIK MINING AND CONSTRUCTION TOOLS AB, 811 81 SANDVIKEN (SE) (74) S.C.P AKKUM, AKKUM & Associates, n° 1777, Rue 6.261, Auditorium Jean Paul II, Quartier Mbankolo, B.P. 4966, YAOUNDE (CM). (57) A coupling for connecting downhole tubulars, comprising a tubular body; a female coupling part; a male coupling part; and at least one of: a male screw thread formed on an outer surface of the body, and a female screw thread formed in an inner surface of the body, wherein: the at least one thread has a thread-form including a crest, a root, and a pair of flanks, the crest and the root are each cambered about a respective first and second camber radius, Rb, Rb-T along the entire length of the thread-form, and each camber radius, Rb, Rb-T, is greater than an outer diameter of the coupling; the male screw thread has a camber radius, Rbm, and the female screw thread has a camber radius, Rbf; characterized in that: each camber radius (Rb, Rb-T) is between 700 - 1900 mm.
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