PEEK vs Carbon Filled PTFE for ball valve seats
PEEK vs Carbon Filled PTFE for ball valve seats
(OP)
Our application is thermal fluid (Paratherm HE) at 400°F and 120PSI.
We are looking at 2" ball valves with either PEEK or carbon filled PTFE seats. Is one a clear winner for any reason? Both seem good to about 500°
We are looking at 2" ball valves with either PEEK or carbon filled PTFE seats. Is one a clear winner for any reason? Both seem good to about 500°





RE: PEEK vs Carbon Filled PTFE for ball valve seats
What will you do for a stem seal?
Mike Halloran
Pembroke Pines, FL, USA
RE: PEEK vs Carbon Filled PTFE for ball valve seats
RE: PEEK vs Carbon Filled PTFE for ball valve seats
Carbon-filled PTFE will probably perform acceptably long term, at 400 F and low pressure. Exceed 450 F though and the carbon-filled Teflon is likely to creep away on you.
There are some valve manufacturers who have been creeping up the well-established upper temperature limit of PTFE from 450 F (232 C) where it has been so for the entire previous generation, to 500 f (260 C), by claiming that their reinforcement/filler material makes that possible- metal powder, graphite, carbon fibre etc. Aside from vendor datasheets making this claim, I've seen no evidence from testing or service history that you can extend that limit to 500 F continuous duty in valve seats and seals with any of these fillers and still expect satisfactory long-term performance. I've asked for that evidence here and received crickets in response, so if anybody has it they've been silent about it.
Where you may be able to get away with this is in services where the service temperature is no more than 450 F but you need a "design" temperature of 500 F to handle brief upsets- then, perhaps, you'd be OK.
RE: PEEK vs Carbon Filled PTFE for ball valve seats
Also agree with moltenmetal, the 'new' uprated valve seating material is not backed with testing or history. If your valves will be hard to maintain or replace, go with PEEK and a longer handle.
RE: PEEK vs Carbon Filled PTFE for ball valve seats