JOINTS FOR HIGH-ALLOY OIL-WELL TUBING WITH RESISTANCE TO CREVICE CORROSION

摘要

A threaded joint having high crevice-corrosion resistance for oil-well tubing of high-alloy containing not less than 7.5% by weight of Cr, has those parts, including the sealing surface, of the joint that are directly exposed to a corroding environment covered with a coating of non-metallic substance 1 to 100 .mu.m in thickness. The coating consists of a single layer or multiple layers of oxide, nitride or carbide ceramics.