VERBINDUNG FUER OELFELDROHRE UND VERFAHREN ZU SEINER HERSTELLUNG.

摘要

This improved joint for oil well pipes comprises a screw portion and a metal-seal portion. A coating layer is formed by a projection coating of particles of soft metal or alloy, the m.pt. of which is higher than the temp. of the environment in which it is placed. The thickness of the projection coating layer lies between 1-30 micro-m. The projection coating is carried out by projecting a blast material contg. particles of the soft metal or alloy. The ave. particle size of the soft metal or alloy is 0.5-1.5 mm and they are projected at a projecting pressure of 2-6 kg f/cm2. The coating layer can be a porous film formed by projecting metal particles each of which consists of a nucleus of Fe or an Fe alloy and a layer of Zn or a Zn alloy formed on the circumferential surface of the nucleus via a layer of an Fe-Zn alloy. The joint itself is made of high alloy steel contg. Cr (5-45 wt.%) and Ni (0-60 wt.%).