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ASTM A312 Material Specification
This specification covers seamless, straight-seam welded, and heavily cold worked welded stainless steel pipe intended for high-temperature and general corrosive service.
Manufacturing Methods: Seamless vs. Welded vs. HCW
Depending on your specific application pressure and environment, the ASTM A312 specification defines three distinct manufacturing pathways:
Seamless Pipe (SMLS): Manufactured without a weld seam, providing superior pressure ratings and structural integrity for critical high-pressure and extreme temperature environments.
Welded Pipe (WLD): Produced using automatic welding processes without the addition of filler metal. For nominal pipe sizes (NPS) 14 and smaller, a single longitudinal weld seam is used. For sizes greater than NPS 14, pipes are formed using two longitudinal sections of flat stock after rigorous technical approval.
Heavily Cold-Worked (HCW) Pipe
ASTM A312 Stainless Steel Pipe shall be made by applying cold working of not less than 35 % reduction in thickness of both wall and weld to a welded pipe prior to the final anneal. No filler shall be used in making the weld. Prior to cold working, the weld shall be 100 % radiographically inspected.
Welded pipe and HCW pipe of 14 and smaller than NPS 14 shall have a single longitudinal weld. After approval by the purchaser, the welded pipe and HCW pipe with an NPS greater than NPS 14 shall have a single longitudinal weld or shall be manufactured by forming and welding two longitudinal sections of flat stock.
Popular ASTM A312 Stainless Steel Grades
The ASME SA 312 standard covers a broad range of austenitic stainless steel grades designed to meet diverse anti-corrosion profiles:
General Corrosion Resistance: TP304, TP304L, TP304H, TP304LN
Marine & High Chemical Resistance: TP316, TP316L, TP316H, TP316Ti, TP317, TP317L
High-Temperature Structural Stability: TP321, TP321H, TP347, TP347H, TP310S
ASTM A312 Chemical Composition
| Grade | Carbon | Silicon | Manganese | Chromium | Nickel | Molybdenum | Sulfur | Phosphorous |
|---|---|---|---|---|---|---|---|---|
| TP304 | 0,08 | 1,0 | 2.00 | 18.0 – 20.0 | 8.0 – 11.0 | – | 0,03 | 0,045 |
| TP304L | 0,035 | 1,0 | 2.00 | 18.0 – 20.0 | 8.0 – 13.0 | – | 0,03 | 0,045 |
| TP316 | 0,08 | 1,0 | 2.00 | 16.0 – 18.0 | 10.0 – 14.0 | 2.00 – 3.00 | 0,03 | 0,045 |
| TP316L | 0,035 | 1,0 | 2.00 | 16.0 – 18.0 | 10.0 – 15.0 | 2.00 – 3.00 | 0,03 | 0,045 |
| TP321 | 0,08 | 1,0 | 2.00 | 17.0 – 19.0 | 9.0 – 12.0 | – | 0,03 | 0,045 |
ASTM A312 Mechanical Properties
| Grade | UNS | Tensile Strength Min, Ksi [MPa] |
Yield Strength Min, Ksi [MPa] |
|---|---|---|---|
| TP304 | S30400 | 75 [515] | 30 [205] |
| TP304L | S30403 | 70 [485] | 25 [170] |
| TP304H | S30409 | 75 [515] | 30 [205] |
| TP304N | S30451 | 80 [550] | 35 [240] |
| TP304LN | S30453 | 75 [515] | 30 [205] |
| TP309S | S30908 | 75 [515] | 30 [205] |
| TP310S | S31008 | 75 [515] | 30 [205] |
| TP316 | S31600 | 75 [515] | 30 [205] |
| TP316L | S31603 | 70 [485] | 25 [170] |
| TP316H | S31609 | 75 [515] | 30 [205] |
| TP316N | S31651 | 80 [550] | 35 [240] |
| TP316LN | S31653 | 75 [515] | 30 [205] |
| TP317 | S31700 | 75 [515] | 30 [205] |
| TP317L | S31703 | 75 [515] | 30 [205] |
ASTM A312 Stainless Steel Pipes OD Tolerance
| NPS | ASTM A312 OD Tolerance | |||
|---|---|---|---|---|
| + | – | |||
| inch | mm | inch | mm | |
| 1/8~1 1 /2 > 1 1 /2~4 > 4~8 > 8~18 > 18~26 > 26~34 > 34~48 |
1/64(0.015) 1/32(0.031) 1/16(0.062) 3/32(0.093) 1/8(0.125) 5/32(0.156) 3/16(0.187) |
0.4 0.8 1.6 2.4 3.2 4.0 4.8 |
1/32(0.031) 1/32(0.031) 1/32(0.031) 1/32(0.031) 1/32(0.031) 1/32(0.031) 1/32(0.031) |
0.8 0.8 0.8 0.8 0.8 0.8 0.8 |
ASTM A312 Stainless Steel Pipes WT Tolerance %
| NPS | ASTM A312 WT Tolerance, % | |
|---|---|---|
| + | – | |
| 1/8-2 1 /2 | 20.0 | 12.5 |
| 3~18, t/D≤ 5% | 22.5 | 12.5 |
| 3~18, t/D> 5% | 15.0 | 12.5 |
| ≥ 20, welded | 17.5 | 12.5 |
| ≥ 20, seamless, t/D≤ 5% | 22.5 | 12.5 |
| ≥ 20, seamless, t/D> 5% | 15.0 | 12.5 |
ASTM A312 Welded And Seamless Pipe Sizes
ASTM A312 stainless steel pipe dimensions and sizes should conform to ANSI B36.19, nominal pipe size (NPS) ranges from NPS 1/8 [10.29 mm] to NPS 30 [762 mm], Schedule number for wall thickness from Sch 5s to Sch 80s, value stated respective for specific size, average wall and minimum wall pipe are available upon request.
Heat Treatment
All ASTM A312 pipe shall be furnished in the heat-treated condition, heat treat temperature for 304/L and 316/L is 1900 deg F (1040 deg C) minimum and then quenched in water or rapidly cooled.
Hydrostatic or Nondestructive Electric Test
Each pipe shall be subjected to the nondestructive electric test or the hydrostatic test.
- Testing And Inspection
- Mechanical Tests
- Grain Size Determinations
- Weld Decay Tests
- Transverse or Longitudinal Tension Test
- Hydrostatic or Nondestructive Electric Test
- Flattening Test (option)
- Radiographic Examination (option)
- Intergranular Corrosion Test (option)
- Weld Decay Test (option)
Reference Documents
- ASTM A999 / A999M – Standard Specification for General Requirements for Alloy and Stainless Steel Pipe
- ASTM A1016 / A1016M – Standard Specification for General Requirements for Ferritic Alloy Steel, Austenitic Alloy Steel, and Stainless Steel Tubes
- ASME B36.10 – Welded and Seamless Wrought Steel Pipe
- ASME B36.19 – Stainless Steel Pipe
