COATING METHOD FOR PIPE HAVING WELD BEAD

摘要

COATING METHOD FOR PIPE HAVING WELD BEAD 5 METHOD OF COATING PIPE HAVING A RAISED WELD BEAD. CURABLE RESIN POLYMER IS APPLIED TO THE PIPE AND ALLOWED TO BOND TO FORM A CURED OR PARTIALLY CURED POLYMER LAYER ON THE PIPE. POWDER FORM ADHESIVE COMPOSITION IS APPLIED ON THE POLYMER LAYER WHILE HOT, WITH FITSION INTO A FILM BONDING TO THE POLYMER. POWDER FORM POLYOLEFIN IS APPLIED ON THE ADHESIVE WHILE HOT WITH FUSION INTO A FILM BONDING TO THE ADLIESIVE TO 10 FORM A POWDER-BASED COATING. FOLLOWING FORMING OF THE POWDER-BASED COATING, THE PIPE IS COOLED FROM THE INSIDE. AN OUTER POLYOLEFIN COVERING IS BONDED TO THE POWDER- BASED COATING AND THE PIPE COOLED TO AMBIENT TEMPERATURE. THIS PROCEDURE CAN AVOID VOIDS, CAVITIES OR PINHOLES FORMING IN THE COATING ADJACENT THE WELD BEAD.