Common standards for stainless steel pipe fittings

There are four main types of most common standards in pipe fittings:

GB12459-90 National Standard for Seamless Butt Welding Pipe Fittings (Seamless)

GB/T13401-92 National standard for welded pipe fittings (with seams),

ANSI B16.9 American Standard Butt Welding Pipe Fitting Standard (Seam or Seamless)

ANSI B16.11 Socket and Threaded Pipe Fitting Standard (American Standard)

Sometimes the following standards are also used:

HG514-87 Ministry of Chemical Industry Pipe Fitting Standard

SHJ408-90 Sinopec Pipe Fitting Standard

JIS B2311, JIS B2312, JIS B2316, Japanese pipe fitting standard

There are also German DIN standards and so on.