ASTM A312 vs A213 vs A268: Which Stainless Steel Standard Your Project Actually Needs
Quick answer: ASTM A312 is for austenitic stainless steel pipe (SS 304, 316) in general corrosive service — plumbing, process piping, pump manifolds. ASTM A213 is for seamless boiler, superheater and heat-exchanger tubing — tighter dimensional and mechanical requirements, hydro-tested. ASTM A268 is for ferritic and martensitic stainless steel tubing (TP409, TP439, TP410) — automotive exhaust, motor shells, heat-shield applications. Choose A312 for pipe, A213 for heat-exchanger tube, A268 for ferritic service where austenitic corrosion resistance is not required.
These three ASTM standards get mixed up on purchase orders more than any other stainless steel spec in the pump, petrochemical and OEM tubing world. The confusion is understandable — all three cover stainless steel tubular products. But they were written for different applications, they carry different testing requirements, and they price differently. Sending an RFQ that cites the wrong one can add 10–20% to landed cost or, worse, disqualify the material at inspection.
This guide breaks each standard down by application, chemistry, dimensional tolerance, testing, and how they cross-reference to European (EN) and Japanese (JIS) equivalents so a global buyer can specify the right standard for the right project.
Key specifications at a glance
| ASTM A312 | ASTM A213 | ASTM A268 | |
|---|---|---|---|
| Product form | Seamless / welded pipe | Seamless tube | Seamless / welded tube |
| Primary microstructure | Austenitic | Austenitic & ferritic alloy | Ferritic & martensitic |
| Typical grades | TP304 / TP304L / TP316 / TP316L / TP317L / TP321 | TP304H / TP316H / TP347H / T22 / T91 | TP405 / TP409 / TP410 / TP430 / TP439 |
| Nominal service | Corrosive fluid transport | High-temp heat transfer | Exhaust, motor shell, structural stainless |
| Dimensional tolerance | Standard NPS tolerances | Tight OD ± 0.10 mm typical | Standard tube tolerances |
| Hydro test | Required | Required | Required for pressure applications |
| Sizes routinely produced | NPS 1/8" – 30" (3 mm – 750 mm OD) | OD 3.2 – 88.9 mm | OD 6.35 – 152.4 mm |
| MTC standard | EN 10204 Type 3.1 (typical) | EN 10204 Type 3.1 (typical) | EN 10204 Type 3.1 (typical) |
Cross-reference — ASTM ↔ EN ↔ IS ↔ JIS
Where a global project needs the material dual-certified (typical for CBAM-compliant UK POs that want both the EN callout for the compliance team and the ASTM callout for the engineering team), Apurvi routinely issues one MTC that cites both standards. The equivalents:
| ASTM | Application | EN equivalent | IS equivalent | JIS equivalent |
|---|---|---|---|---|
| A312 TP304 / TP304L | Austenitic seamless pipe | EN 10216-5 (1.4301 / 1.4307) | IS 6913 | JIS G3459 SUS 304TP |
| A312 TP316 / TP316L | Austenitic seamless pipe, chloride service | EN 10216-5 (1.4401 / 1.4404) | IS 6913 | JIS G3459 SUS 316TP |
| A213 TP304H | Boiler / heat-exchanger tube | EN 10216-5 (1.4948) | IS 6527 | JIS G3463 SUS 304HTB |
| A213 TP316H | Boiler / heat-exchanger tube, chloride service | EN 10216-5 (1.4919) | IS 6527 | JIS G3463 SUS 316HTB |
| A213 T22 (2.25Cr-1Mo) | Alloy boiler tube | EN 10216-2 (10CrMo9-10) | IS 2100 | JIS G3462 STBA24 |
| A268 TP409 | Automotive exhaust, motor shell | EN 10088-2 (1.4512) | IS 6528 | JIS G3448 SUS 409L |
| A268 TP439 | Motor shell, decorative | EN 10088-2 (1.4510) | IS 6528 | JIS G3448 SUS 430LX |
How to choose the right standard for your project
Choose ASTM A312 when…
- You are transporting a fluid — water, brine, chemical, effluent — through a piping system
- Your service is nominally at ambient to moderately elevated temperature (below ~450 °C)
- The corrosion environment justifies austenitic (300-series) chemistry
- You are working to standard nominal-pipe-size (NPS) dimensions and schedules (Sch 10 / 40 / 80 / 160)
- Your project cites EN 10216-5 or EN 10217-7 on the European side — those are the direct equivalents
Choose ASTM A213 when…
- You are building a heat exchanger, boiler, superheater or reformer
- Tighter OD tolerance (typical ± 0.10 mm) is critical for tube-to-tubesheet expansion or brazing
- Service is at high temperature (up to 815 °C for the H-grade austenitics; higher for T22 / T91 alloy grades)
- You need the "H" grade — higher carbon (0.04–0.10%) for creep strength at temperature
- Third-party inspection (SGS / TUV / Lloyd's Register) is likely to be witnessed
Choose ASTM A268 when…
- You are building automotive exhaust (catalytic converter shells, mufflers, downpipes)
- You need a submersible pump motor shell where the chemistry is dry / benign (ferritic 409 is cheap and adequate)
- You need a decorative or architectural application (430-family ferritic)
- You want the corrosion resistance of stainless without the nickel cost of the 300-series (ferritic grades contain little to no nickel)
- Your service temperature is not extreme (ferritic grades lose toughness below −20 °C)
Common questions
1. Can I use A213 tube where A312 pipe is called out?
Sometimes — if the tube meets the dimensional and pressure requirements of the pipe callout. But usually A213 is more expensive due to tighter tolerances and hydro / eddy-current testing. It's over-specification for general-service piping.
2. Is A268 ferritic material weldable?
Yes, but with restrictions. TP409 and TP439 are welded routinely in automotive exhaust manufacturing. The critical rules: use a matching or higher-Cr filler, keep interpass temperature low, and avoid weld metal grain coarsening. A qualified welding procedure specification (WPS) is essential.
3. Which standard cites EN 10204 Type 3.1 MTC?
None of them directly — ASTM A312/A213/A268 reference ASTM A751 for chemical analysis and don't call out EN 10204. But the market convention is to issue an EN 10204 Type 3.1 MTC alongside the ASTM material certificate. Ask for both on the PO.
4. What's the price ranking of the three?
Roughly: A268 ferritic (cheapest, no Ni), A312 austenitic (middle), A213 austenitic (most expensive due to tight tolerances and extra testing). For a like-for-like SS 304 seamless tube, A213 typically runs 15–25% over A312.
5. Do these three standards cover welded tube too?
A312 covers both seamless and welded austenitic pipe. A213 is seamless only. A268 covers both seamless and welded ferritic / martensitic tube — TP439 is very commonly supplied as welded tube for exhaust use.
6. Are these standards recognized in the UK / EU?
Yes — ASTM material with an EN 10204 Type 3.1 MTC is routinely accepted by UK / EU stockists and end users, particularly where the engineer prefers the ASTM grade designation. For CBAM purposes what matters is the origin data on the MTC, not the standard designation.
7. What if my project cites both A312 and A213 on the same PO?
Some pump and pressure-vessel POs do this — A312 for the main manifold piping and A213 for the heat-exchanger tubing package. Cite the correct standard for each line item on the PO and confirm the MTC clearly identifies which standard applies to which heat.
Engineer's checklist before issuing an RFQ
- Application category — piping (A312), heat-exchanger tube (A213), or ferritic exhaust / shell (A268)
- Grade designation (TP304L / TP316L / TP409 / TP439 / etc.)
- OD, wall thickness, length
- Nominal pipe size and schedule (if A312 piping)
- Manufacturing method — seamless or welded
- MTC standard — EN 10204 Type 3.1 required?
- Cross-reference callout — dual-cert to EN / JIS?
- Hydro test / eddy current / hardness test requirements
- Country of melt and country of manufacture (for CBAM / DOC)
- Incoterm and target port of discharge
Have a mixed ASTM / EN specification and want a supplier who can dual-certify on a single MTC?
Send Us Your RFQRelated reading
- SS 304 vs SS 316 for Submersible Pump Motor Tubes (US & UK Guide)
- EN 10204 Type 3.1 MTC Explained (with Annotated Sample)
- How to Source Quality Stainless Steel Pipes in India
- Complete Guide to Stainless Steel Motor Tubes for Submersible Pumps
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- UK buyers — see our UK product landing page