ASTMA420/A420M: American Society for Testing and Materials
Piping Fittings of Wrought Carbon Steel and Alloy Steel for Low-Temperature Service
Scope: These fittings are for use in pressure piping and pressure vessel service at low temperatures.

Chemical Composition
UNS Designation	Composition, %
	Carbon	Manganese	Phosphorus	Sulfur	Silicon	Nickel	Chromium	Molybdenum	Copper	Columbium	Vandium
WPL6	0.30	0.50–1.35	0.04	0.04	0.15–0.40	0.40	0.30	0.12	0.40	0.02	0.08
WPL9	0.20	0.40–1.06	0.03	0.03		1.60–2.24			0.75–1.25
WPL3C	0.20	0.31–0.64	0.05	0.05	0.13–0.37	3.2–3.8
WPL8D	0.13	0.90	0.03	0.03	0.13–0.37	8.4–9.6

Mechanical Properties
Requirement	Grades
	WPL6		WPL9		WPL3		WPL8
Tensile strength, min ksi [MPa]	60 [415] − 95 [655]		63 [435] − 88 [610]		65 [450] − 90 [620]		100 [690] − 125 [865]
Yield strength, min ksi [MPa]	35 [240]		46 [315]		35 [240]		75 [515]
Elongation Requirements	Grades
	WPL6		WPL9		WPL3		WPL8
	Longi-tudinal	Trans-verse	Longi-tudinal	Trans-verse	Longi-tudinal	Trans-verse	Longi-tudinal	Trans-verse
Standard round specimen, or small proportional specimen, min % in 4 D	22	12	20		22	14	16
Rectangular specimen for wall thickness 5⁄16 in. [7.94mm] and over, and for all small sizes tested in full section; min % in 2 in. or 50 mm	30	16.5	28	18	30	20	22
Rectangular specimen for wall thickness less than 5⁄16 in [7.94 mm]; min % in 2 in. or 50 mm (1⁄2-in. [12.7- mm] wide specimen)	A	A	A	A	A	A	A

A For each 1⁄32 in. [0.79 mm] decrease in wall thickness below 5⁄16 in. [7.94 mm], a deduction of 1.5 % (grades WPL6, WPL9, and WPL3) or 1.25 % (WPL8) for longitudinal and 1.0 % (grades WPL6, WPL9 and WPL3) for transverse from the values shown above is permitted. The following table gives the minimum value for various wall thicknesses.

Wall Thickness			Grades
			WPL6		WPL9		WPL3		WPL8
in.	[mm]		Longi-tudinal	Trans-verse	Longi-tudinal	Trans-verse	Longi-tudinal	Trans-verse	Longi-tudinal	Trans-verse
5⁄16 (0.312)	[7.94]		30.00	16.50	28.00	18.00	30.00	20.00	22.00
9⁄32(0.0281)	[7.14]		28.50	15.50	26.50	17.00	28.50	19.00	20.75
1⁄4 (0.250)	[6.35]		27.00	14.50	25.00	16.00	27.00	18.00	19.50
7⁄32 (0.219)	[5.56]		25.50		23.50		25.50		18.25
3⁄16(0.188)	[4.76]		24.00		22.00		24.00		17.00
5⁄32(0.156)	[3.97]		22.50		20.50		22.50		15.75
1⁄8 (0.125)	[3.17]		21.00		19.00		21.00		14.50
3⁄32(0.094)	[2.38]		19.50		17.50		19.50		13.25
1⁄16(0.062)	[1.59]		18.00		16.00		18.00		12.00

1.1 This specification covers wrought carbon steel and alloy steel fittings of seamless and welded construction, covered by the latest revision of ASME B16.9, ASME B16.11, MSS SP-79, MSS SP-83, MSS SP-95, and 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 piping and pressure vessel service at low temperatures.
1.2 Optional supplementary requirements are provided for fittings where a greater degree of examination is desired. When desired, one or more of these supplementary requirements shall be specified in the order.