PTFE / Teflon body seals on ball valves

[stiffler]

Dear all,

I am looking for some advice please.

What I am wanting to know is...are there any ball valve manufacturers who use PTFE body and stem seals on ANSI 600 and above?

Services to include:

Glycol, Natural gas, Hydrocarbons, Methanol
Ambient -46 to +200C teperature range

Thanks for any help,

Stiffler

 

[themad1]

Hi

What do you mean with PTFE doby seal? Do you mean the gasket between body and closure? No rubber (FKM or NBR ORings) ?
Which internal bores are you searching for?

Regards

Daniel

 

[moltenmetal]

The trouble is your 200 C temperature range. Full flange class pressure rating at 200 C may be beyond the limits of PTFE or RTFE body seals- it certainly will be beyond the limits of PTFE/RTFE ball valve seats. Grafoil is typically specified as an alternative.

 

[ET1983]

Hi,

The selection of seal materials for ball valves shall be based on actual maximum and minimum operating temperatures of the valves, pressure fluid composition and chemical product used.
And it is not based on the Line class pressure / temperature design conditions.

ET

 

[bcd]

Most NPS 2 and smaller floating ball valves have PTFE seats, body seals, and stem seals. These are commonly rated as Class 800 when thread or weld end. So answer to your question is "yes, there are ball valve manufacturers who use PTFE body and stem seals on Class 600 and above."

 

[Manichum]

yes

 

[moltenmetal]

bcd: those valves which have class 800 bodies DO NOT have ratings which fall within the entirety of the 600# flange class with respect to temperature. They will withstand 800# class at room temperature, and their temperature/pressure rating is de-rated steeply with increasing temperature beyond about 300 F (150 C) due to the degradation in mechanical properties of the Teflon components. Most floating ball valves are given WOG ratings rather than body class ratings for this reason.