We are having many issues with valves that perform well at ambient but then leak at Cryogenic temperatures. We have done things like:
1. Use heavy spring PTFE jacket seals
2. Achieve surface finish of 4 Ra uin on both the gland ID and gland OD
3. Use Krytox grease
I think the problem is at...
I came up with this equation
Final Thickness * (1+ πΆπππ π πππ’ππ‘πππ %/100) = ππππππππ πβππππππ π
For example, final thickness .005" with 40% cold reduction
.005" * (1+ .4) = .007"
Is this correct?
Yes, Teflon NXT. From our experience it out performs regular PTFE because of its lower porosity and more resistance to wear/shedding in dynamic applications. I will discuss your suggestion with other engineers.
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Uh oh. Yes, modified PTFE (I think you mean the DuPont...
israelkk (Aerospace)
1. Did the valve tested in high temperatures (over 71C degrees) before tested in -320F?
No, it was tested at room temperature
2. What is the diameter of the PTFE seal?
Around 1 inch
3. What is the basis for 1 bubble of helium per one minute at 1000psi requirement?
Not...
Full hard - strip is rolled to half of the original thickness
Half hard - ?
40% cold reduced - ?
How do you calculate the original thickness for half hard and 40% cold reduced? I thought I could find any definition online but I am not able to.
Application data: 1000 psi, -320F, linear travel with .030" stroke length. Yes, LOX is liquid oxygen. Valve Size is about 1 inch.
There are two [dynamic] seals and they have helical coil spring energizers. The jackets are made of modified PTFE. Modified PTFE is used because of its lower...
Israelkk, our customer insists on using Aluminum for weight saving purpose. The sulfuric anodization is sealed per MIL-STD-8625. Even with a 4 Ra, 30 Rz, and 10 Rp finish, do you think the microcracks is still relevant?
IRstuff, I don't know. The only think we could do now is to measure the...
We have a helium/LOX valve that is leaking even with heavy spring PTFE seals. The valve finish is hard anodized aluminum and even with a 4 Ra finish, leakage is higher than desirable.
Can we apply some type of second coating to reduce this leakage? Something to fill up the deep pores in the...
We have a helium/LOX valve that is leaking even with heavy spring PTFE seals. The valve finish is hard anodized aluminum and even with a 4 Ra finish, leakage is higher than desirable.
Can we apply some type of second coating to reduce this leakage? Something to fill up the deep pores in the...
Anyone familiar with API15 C203601 requirements? We sells spring energized PTFE seals and now our customer is asking us if our seals meet this requirements and we don't know. I can't even find a place to purchase this document. Can anyone help?
Guys,
Thanks for your advice. So it is not benefitial to heat treat the Elgiloy for high conc. H2S service because it will increase the embrittlement?
We like to heat treat our Elgiloy springs to improvement yield's strength but I am not sure if heat treatment could hurt in the case of high...
I have two spring materials to choose from for use in a spring energized seal but not sure if Elgiloy or Inconel 718 will be better in term of better resistance to corrosion because of the present of H2S at 17% conc.
Could you please give some advice? If possible, please include source of...
