Using of trim 5 on gate vales in steam service. Is there a temperature you would recommend moving from other trims to trim 5. Is there a better trim than trim 5? When would galling be an issue, if at all? Does "clean" or "dirty" service affect the trim decision?
Typically I would recommend trim 5 more for reduced wear. If the valve is going to be operated frequently it's better to have trim 5, Also if the valve is in an area where it's a huge pain to service Trim 5 might be worth the upgrade.
In terms of valve wear reduction there isn't a much better material than stellite 6.
We use Trim 5 and Trim 8 in steam gate valves here in NYC as a standard. Where Trim 5 is full stellite and 8 is half stellite. Not all too much price difference, but the standard is Trim 8 for most manufacturers so delivery may be easier. If you need tighter longer lasting shut-off, where a gate valve is not a good option, we have moved to bubble tight ball valves.
By the way, the recommendation is not to use stellite for boiler feedwater containing Amines because they will leach the cobolt from the stellite and it comes apart.
From the originalgate valve