using metal seals in a high-pressure, corrosive and high-temperature research vessel 1

[Null Full]

Hello everyone,

We are currently working on a research project that requires a specialized pressure vessel. The vessel needs to be able to withstand 250 bar pressure and a maximum temperature of 350 degrees C, and will contain corrosive gaseous ammonia. Additionally, the vessel features two large windows.

We have currently incorporated 4 o-ring face seals in the design but we are considering switching them out for metal o-ring seals for better performance at high pressures, withstanding corrosive gas and better temperature resistance.

We have some questions for the community:

Does anyone have experience using metal seals that seal properly against non-metallic surfaces such as borosilicate glass, polycarbonate plastic or acrylic plastic?
Are metal seals a direct replacement for standard rubber o-ring grooves?
We would greatly appreciate any insights or advice from those who have experience in this field.

Thank you in advance for your help!

Johnny Huang
Product Manager at Sonkit Industry, For Metal Ring Seal Solution,

https://www.sonkit.cn/en/

 

[TugboatEng]

Your temperature is very high. Consider the thermal expansion. Metal seals will cause wear on the glass. Commercially available boiler sight glasses exist under similar conditions. They use graphite gaskets for sealing and Belleville springs for compression. Boiler water is caustically corrosive. This does wear away at the glass. I don't know how ammonia would compare.

 

[Null Full]

Thanks for the heads up! You're right, the high temp is definitely something we need to keep in mind. Will look into those boiler sight glasses with graphite gaskets and Belleville springs, good call! And yeah, the ammonia vs boiler water wear on the glass is definitely something to consider. We'll keep you all posted on how things go, thanks for the help!

Johnny Huang
Product Manager at Sonkit Industry, For Metal Ring Seal Solution,

https://www.sonkit.cn/en/

 

[TugboatEng]

I don't have an answer for you. I'm only sharing that my industry used Jergusen sight glasses.

 

[Null Full]

Thank you TugboatEng, i will research and keep you updated.

Sonkit
Product Manager at Sonkit Industry, For Metal Ring Seal Solution,

https://www.sonkit.cn/en/

 

[MintJulep]

What size is "large"in your world?

Fused glass sightglasses are typical for challenging conditions.

For example

https://rayoteksightwindows.com

 

[Tkemeny86]

F22 forging and stainless steel inliner...

 

[EdStainless]

I have never tested at your temp, but I have worked at 300C with Aflas elastomers.
The people to contact are Seals Eastern, and no one else in the world.
Not even the folks at Ashai that make the base resin know how to compound it better.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[XL83NL]

Not sure why it hasn’t been mentioned but why not consider FFKM? Certain grades go well above 300 C. We’ve used those for similar conditions as yours.

Huub
- You never get what you expect, you only get what you inspect.

 

[TugboatEng]

Many elastomers will tolerate this temperature for a short time. How long is this vessel expected to operate? FFKM is big money.

 

[MagBen]

Lack of knowledge on metal O-ring, so just for reference:
There does exist a metal group called glass sealing alloy, with mainly Fe-Ni, some cases Co too. they basically have low expansion coefficients matching various glasses. high Ni contents normally >30at%, but no much corrosion resistance.