ASTM A312
Seamless, welded and cold-worked austenitic stainless steel pipe
The main specification for seamless, straight-seam welded and heavily cold-worked welded austenitic stainless steel pipe for high-temperature and general corrosive service.
- Pipe & tube
- ASME SA-312
- 7 grades supplied to it
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is ASTM A312?
ASTM A312 is the specification for seamless and welded austenitic stainless steel pipe for high-temperature and general corrosive service. Grades are written with a TP prefix — TP304L, TP316L, TP321 — and 904L is listed under UNS N08904. General requirements are in ASTM A999 and sizes and wall thicknesses usually follow ASME B36.19. ASME adopts it as SA-312.
ASTM A312 at a glance
| Products | Seamless, straight-seam welded and heavily cold-worked welded pipe |
|---|---|
| Material family | Austenitic and super-austenitic stainless |
| General requirements | ASTM A999 |
| Sizes | ASME B36.19 (5S, 10S, 40S, 80S) and B36.10 schedules |
| Testing | Hydrostatic or electric (non-destructive) test on every length; flattening and other tests per the spec |
| ASME designation | SA-312 |
ASTM A312 grades we supply
The TP grade and UNS number both appear on the certificate.
| Grade | UNS | Typical service |
|---|---|---|
| TP304 / TP304L | S30400 / S30403 | Water, food, general process |
| TP316 / TP316L | S31600 / S31603 | Chlorides, chemicals, pharma |
| TP321 | S32100 | Elevated temperature, intergranular resistance |
| TP347 | S34700 | High-temperature lines |
| 904L (N08904) | N08904 | Dilute sulphuric and phosphoric acid, warm chlorides |
ASTM A312 vs A358 vs A269 / A213 vs A790
Pipe or tube, seamless or fusion-welded, austenitic or duplex — each has its own specification.
| Specification | Covers |
|---|---|
| ASTM A312 | Austenitic pipe, seamless and welded, NPS sizes |
| ASTM A358 | Electric-fusion-welded austenitic pipe from plate, large diameters |
| ASTM A269 | Austenitic tubing for general service, ordered by OD and wall |
| ASTM A213 | Boiler, superheater and heat-exchanger tubes |
| ASTM A790 | Duplex and super duplex pipe |
How to write ASTM A312 on a purchase order
Name the product, size, material specification and grade, the dimensional standard and the certificate. An example line:
Illustrative only — sizes, tests, inspection level and any project values come from your purchase specification.
ASTM A312 edition and verification status
Which edition we have confirmed, and what is still being checked before any numerical requirement is published here.
| Current edition (publisher listing) | A312/A312M-25 — checked 7 October 2026 |
|---|---|
| Full-text verification | In progress — numerical requirements are published here only after the current text has been reviewed |
| Edition on your order | The edition named in your purchase order or design code governs — confirm it with your enquiry |
What to know before ordering to ASTM A312
The points that decide whether material to ASTM A312 is accepted at inspection.
- Sizes and wall thicknesses follow ASME B36.19 (schedules 5S, 10S, 40S, 80S) or B36.10.
- The order must say seamless or welded; both are covered but priced differently.
- Duplex pipe is not in A312 — it is ordered to ASTM A790.
Grades and products we supply to ASTM A312
| Grade | Product | Designation on the certificate |
|---|---|---|
| SS 904L | Pipe & Tube | ASTM A312 (N08904) |
| SS 304 | Pipe & Tube | ASTM A312 TP304 |
| SS 304 | Pipe & Tube | ASTM A312 · A358 |
| SS 304L | Pipe & Tube | ASTM A312 TP304L |
| SS 304L | Pipe & Tube | ASTM A312 · A358 |
| SS 310 / 310S | Pipe & Tube | ASTM A312 TP310S |
| SS 310 / 310S | Pipe & Tube | ASTM A312 · A358 |
| SS 316 / 316L | Pipe & Tube | ASTM A312 TP316L |
| SS 316 / 316L | Pipe & Tube | ASTM A312 · A358 |
| SS 321 | Pipe & Tube | ASTM A312 TP321 |
| SS 321 | Pipe & Tube | ASTM A312 · A358 |
| SS 347 | Pipe & Tube | ASTM A312 TP347 |
| SS 347 | Pipe & Tube | ASTM A312 · A358 |
How ASTM A312 fits into an order
A purchase order line is only complete when it names the material standard, the dimensional standard and the inspection document. Miss one and the mill, the inspector and the buyer can each read the order differently.
Standards used with ASTM A312
Same family
ASTM A312 — questions buyers ask
What is ASTM A312?
ASTM A312 is the specification for seamless and welded austenitic stainless steel pipe for high-temperature and general corrosive service. Grades are written with a TP prefix — TP304L, TP316L, TP321 — and 904L is listed under UNS N08904. General requirements are in ASTM A999 and sizes and wall thicknesses usually follow ASME B36.19. ASME adopts it as SA-312.
What does TP mean in ASTM A312?
"Type" — TP316L is Type 316L. The UNS number (S31603) identifies the same alloy.
Is A312 welded pipe acceptable instead of seamless?
It depends on the piping class. Many classes accept A312 welded pipe (with a joint efficiency factor in the design code); others require seamless. Check your line class.
When is A358 used instead of A312?
A358 is electric-fusion-welded pipe made from plate, usually for large diameters and heavy walls outside the practical seamless range.
Which standard covers 904L pipe today?
ASTM A312 lists UNS N08904. The nickel-alloy specification B677 listed 904L in earlier editions only and still appears on some older purchase orders.
Which grades do you supply to ASTM A312?
SS 904L, SS 304, SS 304L, SS 310 / 310S, SS 316 / 316L, SS 321, SS 347 — see the table on this page for the exact product and designation.
What is the difference between ASTM A312 and ASME SA-312?
ASME SA-312 is the ASME Boiler and Pressure Vessel Code (Section II) adoption of ASTM A312. The technical requirements are usually identical to a specific ASTM edition; pressure-equipment codes call for the ASME designation, and most mill certificates show both.
What is the current edition of ASTM A312?
The publisher's listing checked on 7 October 2026 shows A312/A312M-25 as the current edition. The edition that governs an order is the one named in the purchase order or design code. Full-text review of the current edition is in progress, so numerical requirements are not published on this page yet.
Do you supply certificates to this standard?
Yes. Material is supplied with mill test certificates to EN 10204 3.1 showing the standard, grade and heat number; 3.2 with third-party inspection on request.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026