api 5000API Recommended Practice 500, 4th Edition. API has published API Recommended Practice (RP) 500, Classification of Locations for Electrical Installations at Petroleum FacilitiesAPI 6A6B6BX FLANGE STANDARD, Class 2000PSI, 3000PSI, 5000PSI, 10000PSI, 20000PSI,data sheet including OD, ID, Thickness, Neck dimensions, bolt holes