Stellite seats on steam relief valve

[howkers]

I am having trouble with erosion damage to a relief valve pilot seat from wire drawing in a steam application. The Stellite 6 seat is tapered and gives contact at the top edge. The poppet is of Stellite 12 at slightly shallower angle, about 60 degrees inclusive.

I have been advised that Stellite, although very hard wearing in most valve applications, has a susceptibility to erosion by high velocity steam.

Can anyone confirm this for me. In addition could anyone point me to any authoritative references on this subject/problem.

 

[metengr]

Your information is correct. We have had problems with turbine stop valve steam erosion damage, as well. These are GE turbine stop valves that contain a by-pass during start-up of the machine. The erosion to the Stellite 6 occurred during certain times when the disc skirt was at a certain impingement angle. At one point we had to change out the disc skirts after only 40 hours of accumulated turbine starts. To correct for this problem, we had to go with tungsten carbide on top of the Stellite hardfacing.