ASTM A774 / A774M

This specification covers wrought-carbon steel buttwelding seamless or welded fittings specially processed to ensure better notch toughness than that to be expected in fittings manufactured to the requirements of Specification A234/A234M. Included are elbows, caps, tees, reducers, and other type fittings covered by ASME B16.9. Heat treatment is required for all fittings. Fittings with mandatory radiographic examination of welds are included. Supplementary requirements are provided for use when additional testing or examination is desired. Cast fittings, and fittings formed from all weld metal, are not included.

Chemical Properties

Grade	UNS	Carbon, max^A	Manganese, max	Phosphorus, max	Sulfur, max	Silicon, max	Chromium	Nickel	Molybdenum	Titanium	Columbium + Tantalum	Nitrogen, max

Note A: The carbon analysis shall be reported to the nearest 0.01 % except for the low carbon (0.030) types, that shall be reported to the nearest 0.001 %.

Note B: Ti = 5X(C+N) – 0.70.

Note C: The columbium plus tantalum content shall be not less than ten times the carbon content and not more than 1.10 %.

Mechanical Properties

Grade	UNS	Tensile strength, ksi [MPa]	Yield strength, ksi [MPa]	Elongation in 2 in. [50 mm], min, %	Hardness, max^B
Grade	UNS	Tensile strength, ksi [MPa]	Yield strength, ksi [MPa]	Elongation in 2 in. [50 mm], min, %	Brinell	Rockwell B

Note B: Either Brinell or Rockwell B Hardness is permissible.