Not for the first time I am having a bit of an issue with allegedly stainless steel balls in a loco safety valve. May be just a bad batch……but has anyone tried out ceramic ball bearings in this sort of application? A quick Google of their properties seems to indicate that they would be just the job.
In one of LBSC's articles he suggests putting a ball in the safety, then giving it a sharp strike to bed the valve in. Not sure what would happen with a ceramic..
I use stainless valve bodies and balls on my flash steamer and apart from a bit of dirt now and then they have been good.
The one thing I always check are the stainless balls 316 some of the other stainless balls materials are more magnetic and get a dark gunge colour after a short run in my application.
Have you tried stainless balls from a good brand name bearing supplier such as SKF? Not all balls are created equal, specially those cheapies off the net or through intermediate suppliers for "hobby" use which sometimes seems to mean not the absolute top-of-the-line professional quality gear (with matching price of course).
Years ago used glass balls in place of stainless steel in high pressure check valves, 2500 psi. This was because the material passing through eroded the ball and the glass lasted much longer.
The only issue I have with ceramic balls is that they are prone to pick up any impurities and end up with "crystals" growing on them from what ever is in the water stopping the valve from seating properly. The valves we use at work have to have the balls soaked in a mild acid to remove anything which has grown as a maintenance check.