ASTM A858 / A858M

This specification covers heat-treated wrought carbon steel piping fittings with lowered carbon content of seamless and electric fusion-welded construction covered by the latest revisions in ASME B16.9, ASME B16.11, MSS SP-75, MSS SP-79, MSS SP-83, MSS SP-95, or MSS SP-97. Fittings differing from these ASME and MSS standards shall be furnished in accordance with Supplementary Requirement S58 of Specification A960/A960M. These fittings are for use in pressure components where inherent notch toughness and optimum sulfide-cracking resistance are required, such as oil and gas industry piping and distribution systems.

Chemical Properties

Element	Composition %
Carbon	0.20
Manganese	0.90 – 1.35
Phosphorus	0.030
Sulfur	0.010
Silicon	0.15 – 0.40A
Nickel	0.50B
Chromium	0.30B
Molybdenum	0.20B
Copper	0.35B

Note A: When vacuum carbon deoxidation is used, the silicon shall be 0.10 % maximum, and on product analysis shall not exceed 0.12 %. Note B: The combined total of nickel, chromium, molybdenum, and copper shall not exceed 1.0 %.

Mechanical Properties

Tensile strength, min, ksi [MPa]	Yield strength, min, 0.2 % offset, ksi [MPa]	Elongation
		Standard round specimen,	Rectangular specimen, for section thickness 5/16 in. [7.94 mm] and over	Rectangular specimen for section thickness less than 5/16 in. [7.94 mm]
70 [485] - 95 [655]	36 [250]	22	30	A

Note A: For each 1/₃₂ in. [0.79 mm] decrease in section thickness below 5/₁₆ in. [7.94 mm] a deduction 1.5 % from the 30 % shown above is permitted. Where the section thickness lies between two values defined above, the minimum elongation value is determined by the following equation: E = 5 48t115.00

where: E = elongation in 2 in. [50 mm], and t = actual thickness of specimen, in. B These requirements are intended to minimize fracture initiation. The requirements are not intended to give assurance against fracture propagation.