THREADED JOINT FOR STEEL PIPES

摘要

A threaded joint for steel pipes comprised of a pin (1) and a box (2) each having a threaded portion (1a, 2b) and an unthreaded contact portion (1b, 2a) exhibits adequate leakage resistance and galling resistance when used for makeup of oil country tubular goods with application of a green dope or even without any dope. The threaded joint has a first plating layer of Sn—Bi—Cu alloy plating formed on the contact surface of at least one of the pin (1) or the box (2). The first plating layer may have a second plating layer selected from Sn plating, Cu plating, and Ni plating on its lower side and at least one layer of a lubricating coating, and particularly a solid lubricating coating on its upper side.