B16.6 pipe flanges and flanged fittings
B16.34 valves-flanged,threaded and welding end B31.1 power piping
ASME standard
Section 2 material part
Section 8 rules for construction of pressure vessels
Section 9 welding & brazing qualifications
API standard
598 valve inspection and testing
MSS standard
SP-6 finish for contact faces of pipe flanges and connecting end flanges
of valves and fittings
SP-25 marking system for valves,fittings,flanges and unions
SP-55 quality standard for steel castings for valves, flanges and fittings,
and other piping components (visual method)
Click to enlarge image 
Company