Selection of Gate Valve Trim Assuming Same Design Conditions

http://www.eng-tips.com/viewthread.cfm?qid=142302

Material compatibility with temperature and pressure is normally the the biggest factor in general but frequency of operation of valve can also be a critaria into trim selection. If you have a valve that will be operated very frequently it is advisable to go with a full stellite trim like trim 5. with both surfaces hardfaced the valve will see less wear.

But in 13 Cr-HFS trim only seat is hardfaced and not disc. It is compromised selection and if the frequency of operation is less then this selection can be justified. Disc can be repaired or replaced without dismanteling valve seat in case of failure of valve.