What happen with o-ring if gas is corrosive

[nong]

Our nat gas is corrosive containing high H2S and CO2. o-ring is extended area which cause valve failed. Why?

 

[cranekiran]

Hi!

Pray tell me at what temparature your media is and what is the material of your 'O' Ring?

 

[Hush]

Many elastomers will degrade in H2S environments. CO2 can cause problems in high pressure situations, when the pressure is removed some elastomers will explosively decompress (explode or blister). Anti-corrosives if present can also cause problems particularly the amine based ones. Material hardness is also a factor, the harder the material the more resistant to CO2 or high temp, the lower the hardness the better for low temp and the better the sealing capability. Find out your operating temperatures, pressures and fluid content then phone an elastomer supplier such as Parker for a recommendation. As a general rule for H2S we use HSN for low temp operations (-50F to 250F)and Aflas for higher temps (0F to 400F).