Gas service-Metal seated

[anand25111987]

Dear all,

Greetings!!

Need some expert comments on the below query.

Quite recently on different gas pipeline projects, we are seeing metal seated ball valve requirement even though the line carries CLEAN GAS WITH TEMPERATURE LESS THAN 100 DEG C. We have also checked with the designer on black powder variants in the service which they have denied.On such cases, I presume that RPTFE/PEEK valves can suit the service without any complaints. However, the design consultants claim that the metal suited are more opted for gas applications. For such gas service line is it not soft seated more suitable with its better shut off characteristics?

Need more views and comments on this.

Thanks and Regards,
Anand

 

[georgeverghese]

In my experience, operating company standards require switching out to metal seated trim on ball valves for sizes >DN100 even in clean gas service if there was a requirement for the valve to be operated at pressure differentials in excess of 14bar.