Fittings

• ANSI standard B16.3 covers malleable iron threaded fittings, class 150 and 300. This standard covers screwed malleable iron fittings 3 inches or smaller in diameter. For malleable iron threaded pipe fittings larger than 3 inches, ASTM A47 and ASTM A536 apply. ASTM standard A47 covers malleable or ductile iron fittings 6 inches or larger, if they have a grooved cut.
  
  

Unions

• ANSI standard B16.39 covers malleable iron threaded pipe unions. This standard provides material specifications, dimensions and performance requirements for class 150, 250 and 300 malleable iron threaded pipe unions. This standard covers screwed malleable iron fittings and unions 3 inches and smaller in diameter.
  
  

Flanges

• Malleable iron flanges 6 inches or larger are covered by several standards. According to the "Facility Piping Systems Handbook" by Michael Frankel, this size of malleable iron flanges are built in accordance to "ANSI B16.5, ASTM A47 and ASTM A536."