As I continue my efforts to educate the safety profession in process safety and, more specifically, on the differences between welded pipe joints versus flanged pipe joints, this topic usually comes up. The big question that is the 800-pound gorilla in the room is…
If both welded and flanged joints are allowed in our flammable liquid processes, then why does NFPA 497 only make an exception for welded joints; but not for flanged joints?
First, let’s review what NFPA 497 says about electrical classifications where a “flanged joint” is present.
Please remember, although I have placed this article in my Chemical Process Safety Category, this topic/requirement applies to all flammable liquid processing, not just those over 10,000 pounds. I have simply chosen to keep all my posts regarding electrical classifications in a single category.
(emphasis by me)