Viton A instead of Viton AED

[kalurky]

For a 150# and 300# CS ball valves size 2-4", is it okay to use Viton A as substutute to Viton AED as O-rings? Your thoughts will be much appreciated. Thanks

 

[SJones]

The pressure threshold for rapid gas decompression failure in methane is around 50 bar. This threshold will drop with increasing CO2 content and decreasing hardness of the elastomer, say below 80 IHRD. You may be able to work the data for the Class 150 valve to demonstrate that the risk of RGD failure is acceptable with the properties of the specific Viton A. However, if RGD resistance has been specified, you will struggle to substitute any material that has not been RGD tested for the Class 300 valve.

Take a look at this:

http://www.hse.gov.uk/research/rrhtm/rr485.htm

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04