Stainless steel 304 and 304L pipe fittings are manufactured in compliance with ASTM A-403 and ANSI B16. 9 / 16.28/ MSS SP-43 / Welding Bevel Standards ANSI B 16.25. ... Grade 304 is most commonly referred as the standard 18/8 stainless steel and is one of the most widely used stainless steel grade across the globe