METHOD FOR MANUFACTURE OF PROTECTIVE PART FOR PROTECTION OF EXTERNAL CONICAL THREAD OF PIPE Russian patent published in 2009 - IPC F16L57/00 

FIELD: technological processes.

SUBSTANCE: method includes formation of protective metal body, formation of nonmetal insert, formation of tight connection of protective metal body with nonmetal insert and formation of thread, at that in process of protective metal body formation connection of its edges is done by plasma-arc welding, heating spot center of which is located at the line of edges joint, distance from plasmatron nozzle to surface of body is established as 2.5-3.2 mm, arc voltage is 20-25 V, arc current force is 110-130 A, welding rate is 0.01-0.025 m/sec, and nonmetal insert, internal surface of which is arranged with threaded profile contacting with protected thread is produced by method of melted elastomer injection, for instance, high pressure polyethylene with temperature of 160-180°C in transfer mold with vertical slot and horizontally installed thread-forming sign with delay for 25-95 sec, at that extraction of nonmetal insert from transfer mold is done by return motion of working plate of injection-moulding machine during cooling of polyethylene down to temperature of 50-80°C.

EFFECT: reliable protection of pipe thread against damage and corrosion, simplicity and efficiency of their manufacture.

2 cl