| abstract |
A threaded joint for pipes comprises a pin 1 and a box 2 each having a contact surface including a threaded portion 3,7 and an unthreaded metal contact portion. The unthreaded metal contact portion includes a sealing surface 5, 8 and a shoulder surface 9, 10, 11, 12. The shoulder surface of the pin is located on the end surface of the pin. A non-contacting region 13 in which the pin and the box do not contact each other is present between the sealing surfaces and the shoulder surfaces of the pin and the box. The threaded joint has one or more grooves formed in the shoulder surface of at least one of the pin and the box and extending to the non-contacting region and to the interior of the threaded joint. At least the contact surface of at least one of the pin and the box has a solid lubricating coating exhibiting plastic or viscoplastic rheological behavior formed thereon. The total volume V (mm |