ASTM A312 Standard Specification for Austenitic Stainless Steel Pipe
ASTM A312 is the standard specification covering seamless, welded, and heavily cold-worked austenitic stainless steel pipe intended for high-temperature and general corrosive service.
It is one of the most widely referenced stainless steel pipe standards used in oil & gas, petrochemical, chemical processing, power generation, and industrial piping systems worldwide.
This specification establishes detailed requirements for chemical composition, mechanical properties, heat treatment, dimensional tolerances, testing procedures, and certification.
What Is ASTM A312?
ASTM A312 is issued by ASTM International and applies specifically to austenitic stainless steel pipe used in pressure piping systems.
The standard defines:
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Chemical composition limits
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Minimum mechanical property requirements
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Mandatory heat treatment conditions
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Manufacturing methods
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Testing and inspection requirements
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Product marking and certification
Unlike ASTM A213 (which covers boiler and heat exchanger tubing), ASTM A312 is designed for pipe applications governed by nominal pipe size (NPS) standards.
Scope of ASTM A312
ASTM A312 covers the following product forms:
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Seamless stainless steel pipe
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Welded stainless steel pipe
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Heavily cold-worked pipe
The specification is intended for:
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High-temperature service
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General corrosive service
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Pressure-containing piping systems
Pipe dimensions typically conform to:
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ASME B36.19M (Stainless Steel Pipe)
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ASME B36.10M (Carbon & Alloy Steel Pipe)
Pipe is specified by Nominal Pipe Size (NPS) and schedule, which distinguishes it from tube products.
Manufacturing Types Under ASTM A312
Seamless Pipe (SMLS)
Manufactured without a welded seam, seamless pipe is commonly selected for higher-pressure and critical applications.
Welded Pipe (WLD)
Formed from rolled strip or plate and welded longitudinally. Welded pipe must meet additional weld integrity and testing requirements.
Heavily Cold-Worked Pipe (HCW)
Produced with additional cold working to achieve increased mechanical strength.
Each type must comply with mechanical and testing requirements defined in the standard.
Grades Covered Under ASTM A312
ASTM A312 includes a range of austenitic stainless steel grades.
TP304 / TP304L
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Most widely used general-purpose stainless steel pipe
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Good corrosion resistance
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Suitable for moderate temperature service
TP316 / TP316L
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Contains molybdenum (2–3%)
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Improved resistance to pitting and crevice corrosion
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Preferred for chloride and marine environments
TP321
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Titanium-stabilized grade
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Designed for improved high-temperature stability
TP347
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Niobium-stabilized grade
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Enhanced creep resistance at elevated temperatures
Each grade has specific chemical limits and mechanical requirements defined by ASTM A312.
Chemical Composition Overview (Representative Grades)
TP304
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Chromium (Cr): 18–20%
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Nickel (Ni): 8–11%
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Carbon (C): ≤ 0.08%
TP316
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Chromium (Cr): 16–18%
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Nickel (Ni): 10–14%
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Molybdenum (Mo): 2–3%
The addition of molybdenum in TP316 improves resistance to chloride-induced corrosion compared to TP304.
Exact composition limits should be verified according to the latest ASTM edition.
| Grade | UNS | C (%) | Mn (%) | P (%) | S (%) | Si (%) | Cr (%) | Ni (%) | Mo (%) | Ti (%) | Nb+Ta (%) |
| 304 | S30400 | ≤0.08 | ≤2.00 | ≤0.045 | ≤0.030 | ≤1.00 | 18.0–20.0 | 8.0–11.0 | – | – | – |
| 304L | S30403 | ≤0.035 | ≤2.00 | ≤0.045 | ≤0.030 | ≤1.00 | 18.0–20.0 | 8.0–12.0 | – | – | – |
| 304H | S30409 | 0.04–0.10 | ≤2.00 | ≤0.045 | ≤0.030 | ≤1.00 | 18.0–20.0 | 8.0–11.0 | – | – | – |
| 316 | S31600 | ≤0.08 | ≤2.00 | ≤0.045 | ≤0.030 | ≤1.00 | 16.0–18.0 | 10.0–14.0 | 2.00–3.00 | – | – |
| 316L | S31603 | ≤0.035 | ≤2.00 | ≤0.045 | ≤0.030 | ≤1.00 | 16.0–18.0 | 10.0–14.0 | 2.00–3.00 | – | – |
| 316H | S31609 | 0.04–0.10 | ≤2.00 | ≤0.045 | ≤0.030 | ≤1.00 | 16.0–18.0 | 10.0–14.0 | 2.00–3.00 | – | – |
| 321 | S32100 | ≤0.08 | ≤2.00 | ≤0.045 | ≤0.030 | ≤1.00 | 17.0–19.0 | 9.0–12.0 | – | ≥5×C ≤0.70 | – |
| 321H | S32109 | 0.04–0.10 | ≤2.00 | ≤0.045 | ≤0.030 | ≤1.00 | 17.0–19.0 | 9.0–12.0 | – | ≥5×C ≤0.70 | – |
| 347 | S34700 | ≤0.08 | ≤2.00 | ≤0.045 | ≤0.030 | ≤1.00 | 17.0–19.0 | 9.0–13.0 | – | – | ≥10×C ≤1.10 |
| 347H | S34709 | 0.04–0.10 | ≤2.00 | ≤0.045 | ≤0.030 | ≤1.00 | 17.0–19.0 | 9.0–13.0 | – | – | ≥10×C ≤1.10 |
Mechanical Property Requirements
ASTM A312 specifies minimum mechanical properties including:
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Tensile strength
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Yield strength
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Elongation
For example, TP304 typically requires:
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Tensile strength ≥ 515 MPa
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Yield strength ≥ 205 MPa
Mechanical values may vary depending on manufacturing method and heat treatment condition.
Heat Treatment Requirements
All pipe supplied under ASTM A312 must be heat treated.
Common heat treatment methods include:
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Solution annealing
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Rapid quenching
Proper heat treatment ensures:
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Optimal corrosion resistance
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Structural stability
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Prevention of carbide precipitation
Low-carbon grades such as 304L and 316L reduce the risk of sensitization during welding.
Testing and Inspection Requirements
ASTM A312 requires the following tests:
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Tension test
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Flattening test
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Hydrostatic test or non-destructive electric test
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Intergranular corrosion test (when specified)
Welded pipe must meet additional weld examination requirements.
Material certification is typically provided in accordance with EN 10204 3.1 or 3.2.
ASTM A312 vs ASTM A213
| Feature | ASTM A312 | ASTM A213 |
|---|---|---|
| Product Form | Pipe | Tube |
| Primary Application | Pressure piping | Boiler / Heat exchanger |
| Dimensional Control | NPS & Schedule | OD & Wall Thickness |
| Common Grades | 304, 316 | 304, 316 |
The main difference lies in product form and intended service.
ASTM A312 vs ASTM A269
| Feature | ASTM A312 | ASTM A269 |
|---|---|---|
| Application | Pressure piping | General service tubing |
| Product Form | Pipe | Tube |
| Typical Industry | Oil & Gas | Instrumentation |
Typical Applications of ASTM A312 Pipe
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Oil & gas pipelines
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Petrochemical processing systems
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Power plant piping
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Chemical processing facilities
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Water treatment systems
ASTM A312 pipe is widely selected for pressure systems requiring corrosion resistance and structural reliability.
Frequently Asked Questions
What is the difference between ASTM A312 and A213?
ASTM A312 applies to pipe used in pressure piping systems, while ASTM A213 covers boiler and heat exchanger tubing.
Does ASTM A312 include TP316L?
Yes, TP316L is one of the most commonly specified grades under ASTM A312.
Is ASTM A312 suitable for high-temperature service?
Yes, particularly stabilized grades such as TP321 and TP347 are used for elevated temperature applications.
What is the difference between pipe and tube?
Pipe is specified by nominal pipe size (NPS) and schedule, while tube is defined by exact outside diameter and wall thickness.
Download ASTM A312 Standard Specification (Reference PDF)
A reference overview PDF is available below.
For the official and latest complete standard, please refer to ASTM International.
[Download ASTM A312 PDF]
Related Products:
ASTM A312 TP316L Seamless pipes
