FIELD: machine building.
SUBSTANCE: group of inventions relates to threaded joints. A threaded pipe joint comprises a pin and a box, the pin is fitted by external thread mating the internal thread of the box, the profile shape of the internal and external threads is dovetail with stab and load flanks as well as flat recesses and crests, the width of internal thread lines is increasing in one direction on the box and the width of external thread lines is increasing in the opposite direction on the pin. The thread crests and flanks form seals preventing the fluid medium flow from leaking between them. The threaded joint comprises also fluoropolymer coating applied onto separate sections of the internal and external thread, and resin coating applied onto the internal and external thread sections without fluoropolymer coating. The fluoropolymer coating and resin coating together form a layer of almost equal thickness on the whole surface of the internal and external thread.
EFFECT: method to improve quality of joint threaded surfaces is described.
21 cl, 3 dwg
