Technical features of the ASTM/ASME A/SA 420 specification
The ASTM A420 / ASME SA 420 specification governs the requirements for piping system components (elbows, tees, reducers, caps, and flange connections) manufactured from forged carbon and alloy steel. These products are intended for low-temperature service and are designed for use in seamless or welded piping systems compliant with ASME B16.9, ASME B16.11, MSS-SP-79, MSS-SP-83, MSS-SP-95, and MSS-SP-97 standards.
Size specifications for A420 / SA420 fittings supplied by EV Group China:
- Nominal Pipe Size (NPS): from 1/2″ to 48″ (range of 21.3–1219 mm).
- Wall thickness: Sch 10s, 40s, 80s, 160s, XXS (range of 2.77–59.51 mm).
Products falling outside the standard ASME and MSS dimensional ranges must comply with the additional S58 requirements of the ASTM A960 / A960M standard. Fittings of this specification are optimized for use in high-pressure pipelines and vessels operating under cryogenic or low-temperature conditions.
EV Group China offers the option to order products with additional requirements for testing and surface quality. The specification supports both the inch-pound and the SI metric systems. In the absence of the “M” marking, material parameters are determined in the inch-pound system. Both systems are independent, and mixing them during design is not permitted.
Chemical composition of steel grades according to ASTM A420 / ASME SA420
| Steel Grade | C | Mn | P | S | Si | Cr | Mo | Cu | Cb | V |
|---|---|---|---|---|---|---|---|---|---|---|
| WPL6 | 0.30 | 0.50-1.35 | 0.035 | 0.040 | 0.15-0.40 | 0.30 | 0.12 | 0.40 | 0.02 | 0.08 |
| WPL9 | 0.20 | 0.40-1.06 | 0.030 | 0.030 | – | – | – | 0.75-1.25 | – | – |
| WPL3 | 0.20 | 0.31-0.64 | 0.05 | 0.05 | 0.13-0.37 | – | – | – | – | – |
| WPL8 | 0.13 | 0.90 | 0.030 | 0.030 | 0.13-0.37 | – | – | – | – | – |
For fittings intended for welding, the “W” index is used in the marking. Adjustment of the niobium content to 0.05% (heat analysis) and 0.06% (product analysis) is permitted. Refined manganese limits (up to 0.90% and 0.98% respectively) are provided for plate or forged products.
Mechanical characteristics of ASTM A 420 / ASME SA 420
| Steel Grade | Tensile Strength, MPa (ksi) | Min. Yield Strength, MPa (ksi) | Elongation (Longitudinal), % | Elongation (Transverse), % |
|---|---|---|---|---|
| WPL6 | 415-655 [60-95] | 240 [35] | 22 | 12 |
| WPL9 | 435-610 [63-88] | 315 [46] | – | 14 |
| WPL3 | 450-620 [65-90] | 240 [35] | 22 | 14 |
| WPL8 | 690-865 [100-125] | 515 [75] | 16 | – |
Impact toughness test temperature conditions
| Steel Grade | Temperature (°F) | Temperature (°C) |
|---|---|---|
| WPL6 | -50 | -45 |
| WPL9 | -100 | -75 |
| WPL3 | -150 | -100 |
| WPL8 | -320 | -195 |