Scope and Technical Specifications of ASTM A312 / A312M
The ASTM A312 / A312M standard sets rigorous requirements for the manufacturing of seamless, straight-seam welded, and heavily cold-worked austenitic stainless steel pipes. Products supplied by EV Group China are designed for operation in aggressive corrosive environments and under high-temperature conditions.
Note: Many austenitic steels complying with this specification are approved for use in pressure vessels, boilers, and piping systems without mandatory impact testing, provided criteria for energy absorption (20 J) or lateral expansion (0.38 mm) are met. Grades TP304, TP304L, and TP347 are certified under the ASME Code (Section VIII, Division 1) and ANSI B31.3 standard for operating temperatures down to -250°C. If the carbon content exceeds 0.10% or the composition falls outside AISI limits, impact testing is mandatory for operating environments below -45°C.
Specialized “H” grade pipes (TP304H, TP309H, TP309HCb, TP310H, TP310HCb, TP316H, TP321H, TP347H, TP348H) are modified alloys with enhanced high-temperature strength and creep resistance, optimized for long-term service under extreme temperatures.
For precision engineering tasks, EV Group China offers additional testing upon customer request.
Size range for A312 / SA312 pipes:
- Nominal Pipe Size (NPS): 1/8″ to 30″ (10.3 – 762 mm).
- Wall thickness: In accordance with Schedule (10, 20, 40, 80, 160, STD, XS, XXS) from 1.24 mm to 12.7 mm.
- Calculation base: 1 inch = 25.4 mm.
Geometric parameters of the pipes comply with the ANSI B36.19 standard. For grades TP321 and TP321H with a wall thickness greater than 9.5 mm, reduced strength requirements apply for seamless manufacturing methods.
Chemical Composition of ASTM A312 / ASME SA312 Steel Grades
| Grade | UNS | C max. | Mn max. | P max. | S max. | Si max. | Cr | Ni | Mo max. | Other |
|---|---|---|---|---|---|---|---|---|---|---|
| TP304 | S30400 | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 18.0-20.0 | 8.0-11.0 | – | – |
| TP304L | S30403 | 0.035 | 2.00 | 0.045 | 0.030 | 1.00 | 18.0-20.0 | 8.0-13.0 | – | – |
| TP316 | S31600 | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 16.0-18.0 | 11.0-14.0 | 2.0-3.0 | – |
| TP316L | S31603 | 0.035 | 2.00 | 0.045 | 0.030 | 1.00 | 16.0-18.0 | 10.4-14.0 | 2.0-3.0 | – |
Mechanical Properties of ASTM A312 / ASME SA312
| Grade | UNS | Tensile Strength, MPa | Yield Strength, MPa |
|---|---|---|---|
| TP304 | S30400 | 515 | 205 |
| TP304L | S30403 | 485 | 170 |
| TP316 | S31600 | 515 | 205 |
| TP316L | S31603 | 485 | 170 |
Dimensional Tolerances
EV Group China monitors the accuracy of geometric parameters in accordance with the ASTM A312 specification. Wall thickness deviations vary from -12.5% to +22.5%, depending on the ratio of wall thickness to diameter (t/D).