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.