api 5000API Recommended Practice 500, 4th Edition. API has published API Recommended Practice (RP) 500, Classification of Locations for Electrical Installations at Petroleum FacilitiesOur ASTM A105N flange, with a size of 2-116 inches, adheres to API 6A and TYPE API 6B standards. It boasts a sturdy API 5000 PSI rating, SCH XXS thickness, and an RTJ