Api 5000 Weld Neck Flange

api 5000API Recommended Practice 500, 4th Edition. API has published API Recommended Practice (RP) 500, Classification of Locations for Electrical Installations at Petroleum FacilitiesAPI 5000, 10000 are used in reference to wellhead 'christmas tree' pressure ratings as well used for the wing valve, master valve ratings. There may be hher classes as