In pipe fittings as well, standards play a vital role.

Buttweld Pipe Fitting Specification & Standards

Welded pipe fittings are made as per ASME spec B16.9. ASME B16.9 covers factory made wrought steel butwelding fittings in sizes 1/2″ to 48″. This standard however does not cover low pressure corrosion resistant buttwelding fittings.
A234 WPB is the most common material used for carbon steel butt welded fittings.

ASTM A234 WPB is the Standard Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Moderate and High Temperature Service.

  • ASTM: A234 WPB
  • ASME: B16.9, B.11
  • NACE: MRO175
  • MSS: SP-83, SP-95
WPB Chemical Composition(%)
Grade C Mn P S Si Cr Mo Ni Cu Others
max max
WPB 0.3 0.29-1.06 0.05 0.058 0.1 0.4 0.15 0.4 0.4 V 0.08
(1,2,3,4,5) max min max max max max max
  • Fittings made from bar or plate may have 0.35 max carbon.
  • Fittings made from forgings may have 0.35 max Carbon and 0.35 max Silicon with no min.
  • For each reduction of 0.01% below the specified Carbon maximum, an increase of 0.06% Manganese above the specified maximum will be permitted, up to a maximum of 1.35%.
  • The sum of Copper, Nickel, Niobium, and Molybdenum shall not exceed 1.00%.
  • The sum of Niobium and Molybdenum shall not exceed 0.32%.

In ASME/ANSI standard, butt welding pipe fittings technical requirements are specified in the standard ASME/ANSI B16.9, including all the types of pipe fittings. In EN standard, it is EN10253 standard for the butt welding pipe fittings.

In JIS, DIN, Ghost standard, different type of butt welding fittings are in different standard number. For example, JIS B2311, B2312, B2313  or GOST 17373, GOST 17375, GOST 17376, GOST 17378 etc.
There are also some other standards about butt welding pipe fittings like:

  • MSS SP-43
  • MSS SP-75
  • ASME B16.49

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