ASTM A312 Stainless Steel Pipe Specification, Grades, Applications
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What is the scope of the ASTM A312 specification?
ASTM A312 is the primary standard specification for austenitic stainless steel tubing, applicable to high-temperature and highly corrosive environments. It covers seamless tubing, straight-seam welded tubing, and heavily cold-worked tubing, and specifies stringent manufacturing, dimensional, and testing standards for seamless and welded tubing used in demanding industries such as oil refineries, chemical plants, and power generation.
ASTM A312 Stainless Steel Pipe Scope and Manufacturing
Seamless (SMLS): Manufactured without a weld seam.
Welded (WLD): Manufactured using an automatic welding process with no addition of filler metal.
Common Grades: TP304, TP304L, TP316, TP316L, TP321, TP347, TP904L.
Chemical Composition
According to ASTM A312, the chemical requirements (max % unless a range is given) are:
| Grade | UNS | C | Mn | P | S | Si | Cr | Ni | Mo |
| TP304 | S30400 | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 18.0–20.0 | 8.0–11.0 | - |
| TP304L | S30403 | 0.03 | 2.00 | 0.045 | 0.030 | 1.00 | 18.0–20.0 | 8.0–12.0 | - |
| 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 | 0.03 | 2.00 | 0.045 | 0.030 | 1.00 | 16.0–18.0 | 10.0–14.0 | 2.0–3.0 |
| TP904L | N08904 | 0.02 | 2.00 | 0.040 | 0.030 | 1.00 | 19.0–23.0 | 23.0–28.0 | 4.0–5.0 |
Mechanical Properties
The pipe must conform to the following tensile and hardness requirements:
| Grade | Tensile Strength (min) | Yield Strength (min) | Elongation in 2 in. (min) |
| TP304 / 316 | 515 MPa (75 ksi) | 205 MPa (30 ksi) | 35% |
| TP304L / 316L | 485 MPa (70 ksi) | 170 MPa (25 ksi) | 35% |
| TP904L | 490 MPa (71 ksi) | 220 MPa (32 ksi) | 35% |
ASME B36.19 / ASTM A312 Stainless Steel Pipe Dimensions
The standard applies to pipes ranging from NPS 1/8" to 30" (DN6 to DN750) with wall thicknesses conforming to ASME B36.19 schedules (e.g., SCH 10S, 40S, 80S, XXS).
| NPS (Inch) | DN (mm) | Outside Diameter (mm) | Sch 5S (WT mm) | Sch 10S (WT mm) | Sch 40S (WT mm) | Sch 80S (WT mm) |
| 1/8" | 6 | 10.3 | - | 1.24 | 1.73 | 2.41 |
| 1/4" | 8 | 13.7 | - | 1.65 | 2.24 | 3.02 |
| 3/8" | 10 | 17.1 | - | 1.65 | 2.31 | 3.20 |
| 1/2" | 15 | 21.3 | 1.65 | 2.11 | 2.77 | 3.73 |
| 3/4" | 20 | 26.7 | 1.65 | 2.11 | 2.87 | 3.91 |
| 1" | 25 | 33.4 | 1.65 | 2.77 | 3.38 | 4.55 |
| 1-1/4" | 32 | 42.2 | 1.65 | 2.77 | 3.56 | 4.85 |
| 1-1/2" | 40 | 48.3 | 1.65 | 2.77 | 3.68 | 5.08 |
| 2" | 50 | 60.3 | 1.65 | 2.77 | 3.91 | 5.54 |
| 2-1/2" | 65 | 73.0 | 2.11 | 3.05 | 5.16 | 7.01 |
| 3" | 80 | 88.9 | 2.11 | 3.05 | 5.49 | 7.62 |
| 4" | 100 | 114.3 | 2.11 | 3.05 | 6.02 | 8.56 |
| 5" | 125 | 141.3 | 2.77 | 3.40 | 6.55 | 9.53 |
| 6" | 150 | 168.3 | 2.77 | 3.40 | 7.11 | 10.97 |
| 8" | 200 | 219.1 | 2.77 | 3.76 | 8.18 | 12.70 |
| 10" | 250 | 273.1 | 3.40 | 4.19 | 9.27 | 12.70* |
| 12" | 300 | 323.9 | 3.96 | 4.57 | 9.53 | 12.70* |
When ordering, always specify the NPS (Nominal Pipe Size), Schedule (Wall Thickness), Grade, and Manufacturing Method (Seamless or Welded).
Example: ASTM A312 TP316L SMLS, NPS 1, Sch 40S, 6000mm length.
ASTM A312 Tolerances
ASTM A312 tolerances specify the permissible variations in outside diameter, wall thickness, and length for seamless and welded stainless steel pipe, as outlined in the table below:
| STANDARD | OD(D) | TOLERANCE(MM) | THICKNESS(S) | TOLERANCE | LENGTH | TOLERANCE |
| MM | COMMON HIGH | MM | MM | MM | ||
| A312 | 10.3≤D≤48.3 | +0.4/-0.8 | 10.3≤D≤73.0 | +20%/-12.5% | For all sizes | +6.0/0 |
| 48.3 | +0.8/-0.8 | 88.9≤D≤457.2,ID<5% | +22.5%/-12.5% | |||
| 114.3 | +1.6/-0.8 | 88.9≤D≤457.2,ID>5% | +15%/-12.5% | |||
| 219.1 | +2.4/-0.8 | D≥508.0,tD≤5%,SMLS | +22.5%/-12.5% | |||
| 457.2 | +3.2/-0.8 | D≥508.0,tD>5%,SMLS | +15%/-12.5% | |||
| 660.4 | +4.8/-0.8 | D≥508.0, WLD | +17.5%/-12.5% | |||
| 863.6 | +4.8/-0.8 |
ASTM A312 Stainless Steel Pipe Weight Chart ( kg/m )
| NPS (Inch) | DN (mm) | OD (mm) | Sch 10S (WT mm) | Weight ( kg/m ) | Sch 40S (WT mm) | Weight ( kg/m ) | Sch 80S (WT mm) | Weight ( kg/m ) |
| 1/8" | 6 | 10.3 | 1.24 | 0.28 | 1.73 | 0.37 | 2.41 | 0.48 |
| 1/4" | 8 | 13.7 | 1.65 | 0.50 | 2.24 | 0.64 | 3.02 | 0.81 |
| 3/8" | 10 | 17.1 | 1.65 | 0.64 | 2.31 | 0.86 | 3.20 | 1.11 |
| 1/2" | 15 | 21.3 | 2.11 | 1.01 | 2.77 | 1.28 | 3.73 | 1.64 |
| 3/4" | 20 | 26.7 | 2.11 | 1.30 | 2.87 | 1.71 | 3.91 | 2.23 |
| 1" | 25 | 33.4 | 2.77 | 2.12 | 3.38 | 2.54 | 4.55 | 3.29 |
| 1-1/4" | 32 | 42.2 | 2.77 | 2.73 | 3.56 | 3.44 | 4.85 | 4.54 |
| 1-1/2" | 40 | 48.3 | 2.77 | 3.16 | 3.68 | 4.11 | 5.08 | 5.50 |
| 2" | 50 | 60.3 | 2.77 | 3.99 | 3.91 | 5.52 | 5.54 | 7.60 |
| 2-1/2" | 65 | 73.0 | 3.05 | 5.34 | 5.16 | 8.77 | 7.01 | 11.59 |
| 3" | 80 | 88.9 | 3.05 | 6.56 | 5.49 | 11.47 | 7.62 | 15.51 |
| 4" | 100 | 114.3 | 3.05 | 8.50 | 6.02 | 16.32 | 8.56 | 22.67 |
| 5" | 125 | 141.3 | 3.40 | 11.74 | 6.55 | 22.10 | 9.53 | 31.44 |
| 6" | 150 | 168.3 | 3.40 | 14.04 | 7.11 | 28.70 | 10.97 | 43.23 |
| 8" | 200 | 219.1 | 3.76 | 20.28 | 8.18 | 43.21 | 12.70 | 65.65 |
| 10" | 250 | 273.1 | 4.19 | 28.22 | 9.27 | 61.24 | 12.70 | 82.83 |
12" |
300 | 323.9 | 4.57 | 36.55 | 9.53 | 74.96 | 12.70 | 99.00 |
Heat Treatment & Surface Finish
Solution Annealing: All pipes are furnished in the heat-treated condition. The minimum solution temperature is typically 1900°F (1040°C), followed by rapid quenching in water or air.
Pickling: Pipes are typically pickled (descaled) to ensure a clean, corrosion-resistant surface.
Bright Annealing (BA): Optional; provides a mirror-like surface by annealing in a protective atmosphere.
ASTM A312 Standard Tests and Inspections
Hydrostatic Test: Each pipe is tested to ensure no leakage under pressure (unless Eddy Current tested).
Eddy Current Test: Non-destructive testing for surface and sub-surface defects.
Flattening Test: Performed on sections from each end of the pipe to check for ductility.
Flaring Test (for Tubing): Ensures the pipe can expand without cracking.
PMI (Positive Material Identification): To verify chemical composition.
Visual and Dimensional Inspection: To ensure compliance with ASTM A999.
GNEE Stainless Steel offers products that meet ASTM A312 standards and come with an MTC (Material Testing Certificate) 3.1, stating that all pipes are 100% PMI tested.
What is the difference between ASTM A312 and ASTM A269?
ASTM A312 (Pipe): Sized by NPS (Nominal Pipe Size) and Schedule. It is used for fluid transport and structural piping.
ASTM A269 (Tubing): Sized by actual Outside Diameter (OD) and Wall Thickness (WT). It is used for instrumentation, heat exchangers, and general service tubing where precise dimensions are required.
Below is the ASTM A312 technical document we provide, which we hope will be helpful to your project. Click to get it!
