The basic principle of coupling and pup joints phosphating Phosphating refers to the process in which the metal is treated in a solution containing phosphate to form a phosphate chemical conversion film on the metal surface. The resulting metal phosphate chemical conversion film is called a phosphating film.The successful application of phosphating process to replace galvanized process in tubing coupling greatly improves the product quality of tubing and solves the problem of anti-corrosion of coupling.
