RE: stellite coating
Spraying ball valves is rather difficult. The biggest limitations are in the bore. Thermal spray is a line of sight process, and the particles need to hit the substrate at a minimum angle. Below this angle, the particles simply bounce off. In the case of a 4" ball, the bore is very small so it is virtually impossible to coat the ID. Also, where the bore transitions to the OD, there is a high heat and stress concentration during spraying, so it is difficult to spray without cracking the coating. I am not aware of another method to protect the bores of the balls. Perhaps someone else on the forum knows something.
|