Electrical Classification of Furnaces

[rocketscientist15220]

Hi,

I am doing an electrical area classification of a heater at a refinery. I am concerned because the client specification calls on us to unclassify not only the stack but also the entire burner. Is this an acceptable practice? Of course, the inside of the furnace will be unclassified because anything inside will burn. Unclassifying the burner does not make sense because I've seen gas leaks. Normally, API 500 allows a 15 ft length and a 25 radius around sources. Our client has also asked us to focus only on primary sources. We are to ignore flanges and hand valves because operators will detect such leaks. All of this seems a little loose. I was wondering what others are doing about electrical classification.

 

[rbalex]

The general API-RP500 rationale with respect unclassified locations is Section 6.2.4 with particular respect to non-electrical ignition sources in Section 6.2.4.3. You may also want to review Section 9.1.5 and its surrounding text.

It is important to understand API-RP500 is a ?Recommended Practice;? it is not a Code or even a Standard. Most Electrical Area Classification is an ?experience? issue and your client may have adequate experience with their proposed design. If you have a searchable copy, look for ?experience? and review how it is applied.

It is also important to recognize that API-RP500 is an ANSI sanctioned document so it is a VERY STRONG recommended practice.

BTW welcome to the forums. It is a pleasant surprise to see a Process Engineer creating the Electrical Area Classification Documents.