Coupling with setpoint tightening torque

Coupling (100, 200) with a setpoint tightening torque for connecting two pipes (C1, C2) comprising:

• a first end piece (1) attached to a first pipe (C1),
• a second end piece (2) attached to a second pipe (C2),
• a clamping nut (3) that is borne by the second end piece (2) and clamps the latter against the first end piece (1),
• the first end piece (1) having on its free side a threaded segment (12) terminating in an end forming a sealing surface (13),
• the second end piece (2) having an end designed to be clamped against the sealing surface (13) of the first end piece (1),
• the nut (3) fitted freely rotating on the second end piece (2), overlapping it and screwing (31) onto the threaded segment (12) of the first end piece (1) to push the end of the second end piece (2a) and clamp it against the sealing surface (13),
• coupling (100) being characterized in that
• the first end piece (1) has a nut crown (11) for holding the end piece (1) for the screwing thereof and an angular reference (111);
• the nut (3) has an index (311), and
• the run-out and the pitch of the thread of the threaded segment (12) of the first end piece (1) and the run-out and the pitch of the internal thread of the threaded segment (33) of the nut (3) are designed so that the positioning of the index (311) of the nut (3) with respect to the angular reference (111) of the first end piece (1) corresponds to the tightening of the coupling (100).