METHOD FOR ENAMELING INNER SURFACES OF PIPES FOR MANUFACTURE AND MOUNTING OF PIPELINES BY WELDING Russian patent published in 1996 - IPC

FIELD: manufacture and mounting of pipelines by welding. SUBSTANCE: method involves preparing surface and applying enamel slip; drying and calcining; forming additional layer of enamel coating in the form of ridge on pipe ends by heating end of pipe rotating at linear speed of 50-200 mm/sec beginning from pipe end. Enamel powder with melting temperature 20-100 deg below temperature at which main coating layer is formed may be used to form coating. Enamel powder is added, when pipe end temperature reaches 600-800 C, and is continuously added till final temperature providing formation of main layer of coating is reached. EFFECT: increased efficiency of method and improved quality of coating. 1 tbl