They should be comprehensively explained in the relevant mechanical construction standard relating to refineries (I don't know what it is called thou). I don't have the link to the American standard database, but the European standards link is below.

http://www.iec.ch/searchpub/cur_fut.htm

Check the ASTM standards, the NFPA [national fire protection association]guidelines, and perhaps OSHA for starters. If you are working for an Oil company, go directly to you safety officer and he will have all the data you will need. If you are a consultant or an inventor contact Art Hendela @ hendela.com as he consulted for Exxon for many years and may be able to point you in the right direction as a courtesy.

good luck

Hi, this is Art Hendela. I would be glad to chat with the person who originally posted to this blog. They may not have been able to reach me because my email is art.hendela @ hendela.com. I appreciate that you separated the parts of the email so I do not get bombed with spam. My site may have some presentations on it that may help. Use the search facility at http://www.hendela.com , email me as above, or call me at 1-973-890-0324.