gary m pitman
I am guessing you have the FLOWSERVE/TK valve 6″ x 2500 air actuator ball valve for your water isolation.
One thing that may help is using a sealant to prevent high pressure water from getting in the body. On the outside of the body there is a Lincoln head grease fitting that we pumped silicone sealant into.
I think that the OEM has something about this??
Packing the area around the ball helps to prevent coke laden high pressure water from entering the ball to body cavity causing erosion.
Some of the time the body is too eroded to rebuild.
It is a best practice to include this pumping of the sealant in a routine preventative maintenance package to prevent damage to the valve.
If the valves have been rebuilt, the tolerances may be incorrect on the seals around the ball to keep any water from getting into the body area.
There may be bull plugs in the body and someone will have to remove those and install the Lincoln head fitting. I can send some photo examples if you wish, contact me at the address below.