Seat Insert for ball valve 1

[ligin18]

HI
For Full bore ball valve (16"sour service- piggable line) the seat insert is RPTFE. But vendor is offering Devlon instead of RPTFE. Plz clarify whether Devlon can be accept instead of RPTFE. Design condition is -3/120 C and pressure class is 150#

 

[mk3223]

The vendor may provide the detail data of the chemical resistance and the P-T rating for the Devlon.

 

[Danlap]

The acceptance mainly depending on two factor: the design or operating condition (you are still missing the operating pressure and temperature). And the design philosophy of this valve.
Generally and conservatively speaking, soft seated ball valve may have several seat selection. Viton (up to 80 degC), Devlon (120 degC), RPTFE and or VirginPTFE (up to 150 degC or some vendor may argue this is up to 200degC).
So by this regards, Devlon is pretty much on the border line, shall the service temperature approx. 120degC.

Design philosophy, kindly provide us with further information over below questionnaire:
- Is this for piping or pipeline?
- Flange or butt welded top entry ball valve?
- Normally open or normally close?
- Frequent of operation?
- Is Tight Shut Off requirement (zero leakage up to x years without maintenance) mandatory for this valve?

For example:
If this sour medium is hazardous, and the butt welded valve is located next to the PIG launcher, and must be zero leakage (in close position) when operator/inspector insert the PIG. And for instance PIG-ing is commenced every 4 years for the next 20 years without major maintenance on the ball valve. Then I would recommend to use PEEK instead of RPTFE, PTFE or Devlon. Simply due to the extra strength PEEK has in comparison with others.

Hope you got the idea.

Regards,
MR

https://nosuchvalve.com

All valves will last for years, except the ones that were poorly manufactured; are still wrongly operated and or were wrongly selected

http://www.eng-tips.com/faqs.cfm?&rat1=2&fid=376

 

[ligin18]

Hi

Thanks alot.

Its a pipeline full bore fanged piggable ball valves which will be normally closed(produced water with high chloride content 140K ppm).As per Client requirement the seat material shall be RPTFE minimum.