×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Cryogenic Valve Seat

Cryogenic Valve Seat

Cryogenic Valve Seat

(OP)
Has anybody tried Vespel for Cryogenic valve seats? Any comments on the performance is most welcome.

RE: Cryogenic Valve Seat

As far as I can understand, FFV5 question is not about cryogenic extension bonnets (meant to take the valve stem sealing system away from the cold fluid), but about the internal, main sealing system (seat and obturator) of the valve.

Regards,
           'NGL

RE: Cryogenic Valve Seat

FFV5,
I have used Vespel for valve seats but only in nuclear applications where the cost could be justified. These applications were typical power plant valves at water and steam temperatures.

We have made thousands of globe cold box valves and the typical valve soft seat material is Kel-F PCTFE (PolyChloroTriFluoroEthylene). The characteristics are very similar to PTFE but there is some marginal flexability at cryogenic temperatures.

Kel-F was developed by 3M but the only remaining source is Daikin Industries in Japan.
Hope this helps,
ABScott

RE: Cryogenic Valve Seat

(OP)
Yup Thanks abscott for your comments. I was choosing between Vespel and Kel-F. Our internal tests has revealed that the coefficient of thermal expansion of Kel-F is more unpredictable as compared to Vespel. In addition, Vespel seems to be able to take a higher pressure. I thought it might be sutable to be use for high pressure cryogenic valve seats but I would like to gather some reviews.

RE: Cryogenic Valve Seat

Arkema also makes PCTFE in the EU.

http://www.arkema-inc.com/index.cfm?pag=110

The crystalinity of PCTFE can vary. That maybe the source of the variation in CTE.

What do you consider high pressure?

RE: Cryogenic Valve Seat

Meldin is the same as Vespel at half the cost.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources