METHOD FOR CONTINUOUS PRODUCTION OF METAL PIPES WITH POLYMERIC COATING Russian patent published in 1999 - IPC

FIELD: mechanical engineering. SUBSTANCE: this relates to manufacture of metal pipes having its external and internal surfaces coated with polymeric material. According to method, production process includes following operations: metal band is formed into circular profile, edges of circular profile are welded together, internal and external polymeric shells are made by extrusion and they are introduced into pipe for contact with metal surfaces through interlayer of clay. Initially formed is internal polymeric shell, then formed coaxially is circular profile of metal band and its edges are welded together. Introduction of internal polymeric shell for contact with metal surface through interlayer of clay is effected during formation of circular profile or when welding edges of circular profile or after welding of circular profile edges. Metal bend is formed into circular profile so that its edges are in butt contact. Clay is applied to external surface of internal polymeric shell and to external surface of metal pipe or to one side of metal band and to external surface of metal pipe or to both sides of metal band. Application of aforesaid method allows for independent setting of any temperature conditions when processing polymeric materials and clay. It makes no design limitations as to dimensions of extrusion heads and of other devices involved in process. It considerably increases productivity of process and simplifies quality control. EFFECT: higher efficiency. 2 cl