Technical Overview of ASTM/ASME A/SA 403 Standard
The ASTM/ASME A/SA 403 specification defines stringent requirements for the production of wrought pressure-containing piping fittings. The document details technical parameters for a wide range of austenitic stainless steel grades. Products are classified into WP and CR categories, corresponding to ASME and MSS standards respectively.
Manufacturing methods are defined for each WP class: seamless construction or welded construction. The class designation system in the specification also establishes Nondestructive Examination (NDE) protocols and quality requirements for welded joints.
Table 1 contains comprehensive information on the classification of WP grade fittings that meet EV Group China requirements. Specialized industry standards apply to CR grade products.
Technical parameters are presented in two measurement systems: inch-pound and SI. Values provided without [M] marking are the base values in the inch-pound system. It is important to note that values in different systems are not direct equivalents and should be applied independently to avoid violations of the standard requirements.
This standard does not cover cast fittings. Characteristics for cast stainless and austenitic alloy products are governed by standards A351/A351M, A743/A743M, and A744/A744M.
Chemical Composition of Steels for ASTM A403 / A403M Fittings
| Steel Grade | Chemical Composition, % | |||||||||||||||
| Grade WP | Grade CR | UNS | C | Mn | P | S | Si | Ni | Cr | Mo | Ti | Nc | Others | |||
| WPXM-19 | CRXM-19 | S20910 | 0.06 | 4.0-6.0 | 0.045 | 0.030 | 1.00 | 11.5-13.5 | 20.5-23.5 | 1.50-3.00 | – | 0.20-0.40 | – | |||
| WP304 | CR304 | S30400 | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 8.0-11.0 | 18.0-20.0 | – | – | – | – | |||
| WP316 | CR316 | S31600 | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 10.0-14.0 | 16.0-18.0 | 2.00-3.00 | – | – | – | |||
Heat Treatment
| Grade WP | Grade CR | UNS | Temperature, min °C | Cooling |
| WP304 | CR304 | S30400 | 1040 | Water or rapid cooling |
| WP316 | CR316 | S31600 | 1040 | Water or rapid cooling |
Mechanical Properties
| Grade | Yield Strength (MPa) | Tensile Strength (MPa) |
| 304/316 | 205 | 515 |