What is ASTM A312?
ASTM A312 is the material specification for seamless, straight-seam welded and heavily cold-worked austenitic stainless steel pipe intended for high-temperature and general corrosive service.
Key Takeaways
- ASTM A312 scope: Chemical composition, mechanical properties, heat treatment, hydrostatic or non-destructive electric testing, and permissible dimensional tolerances for austenitic stainless pipe.
- Size range: NPS 1/8 inch to 30 inch, in schedules from SCH 5S to SCH XXS.
- Ratings: Rated by schedule and wall thickness rather than by class.
- Material grades: TP304, TP304L, TP304H, TP316, TP316L, TP316H, TP321, TP347 and TP310S.
- Kalp Alloys manufactures to ASTM A312 in Ahmedabad, India, with EN 10204 3.1 and 3.2 certification issued in its own name.
- Third-party inspection by SGS, BV, TUV or Lloyds can be witnessed at our plant before dispatch.
What ASTM A312 governs
ASTM A312 is the material specification for seamless, straight-seam welded and heavily cold-worked austenitic stainless steel pipe intended for high-temperature and general corrosive service.
Chemical composition, mechanical properties, heat treatment, hydrostatic or non-destructive electric testing, and permissible dimensional tolerances for austenitic stainless pipe.
Scope, sizes and ratings at a glance
The envelope below is the practical reference: what to state on a purchase order so the item that arrives is the item the line needs.
| Parameter | Detail |
|---|---|
| Size range | NPS 1/8 inch to 30 inch, in schedules from SCH 5S to SCH XXS |
| Ratings | Rated by schedule and wall thickness rather than by class |
| Material grades | TP304, TP304L, TP304H, TP316, TP316L, TP316H, TP321, TP347 and TP310S |
| TP304 / TP304L | General corrosion resistance; L for weld-sensitisation resistance |
| TP316 / TP316L | Molybdenum-bearing; better chloride and pitting resistance |
| TP321 / TP347 | Titanium and niobium stabilised for elevated temperature |
| TP310S | High-chromium, high-temperature oxidation resistance |
| H grades | Controlled higher carbon for creep strength above 525 degrees Celsius |
| Schedules | SCH 5S and 10S thin wall through SCH 40, 80, 160 and XXS |
| Seamless vs welded | Both permitted; seamless for high-pressure, cyclic and sour service |
The point buyers most often get wrong
The choice between seamless and welded under A312 is a genuine engineering decision rather than a pure cost one. Seamless pipe has no longitudinal weld and is normally specified for high-pressure, cyclic or sour service. Welded pipe made to A312 is fully tested and entirely code-acceptable for most service, and above roughly 8 inch it becomes both more available and more economical. The specification permits both; the project specification decides.
What Kalp Alloys manufactures to ASTM A312
Kalp Alloys is a manufacturer, not a stockist. Production runs at our own facility at 5, Jay Vijay Industrial Estate, B/h. Akash Vikas Estate, Keval Kanta Road, Rakhial, Ahmedabad, which means the heat number stamped on the part traces to our own melt record and the mill test certificate is issued in the name of Kalp Alloys.
That matters on standard-led purchasing more than anywhere else, because an approved-vendor submission or a code-governed line has to show who made the part. A certificate passed down a trading chain names a mill the buyer has no relationship with and cannot query.
Grades supplied against ASTM A312 cover TP304, TP304L, TP304H, TP316, TP316L, TP316H, TP321, TP347 and TP310S. Non-standard bores, thicknesses, drilling patterns and facing finishes are produced to customer drawing.
Ordering against ASTM A312
State the dimensional standard, the size or NPS range, the rating or schedule, the facing where applicable, the material specification and grade, the quantity, and the certification level required. A quotation is typically returned within 24 hours.
Drawings for non-standard items can be sent by email or on WhatsApp at +91 81608 73937 and are reviewed by the technical team. Stock sizes dispatch in three to seven days; made-to-drawing items carry a firm lead time quoted at order confirmation. There is no minimum order on stock sizes and trial quantities are accepted.
Frequently Asked Questions
ASTM A312 is the material specification for seamless, straight-seam welded and heavily cold-worked austenitic stainless steel pipe intended for high-temperature and general corrosive service.
NPS 1/8 inch to 30 inch, in schedules from SCH 5S to SCH XXS. Ratings covered are Rated by schedule and wall thickness rather than by class.
TP304, TP304L, TP304H, TP316, TP316L, TP316H, TP321, TP347 and TP310S.
The S suffix denotes the stainless steel schedule series, which carries thinner walls than the equivalent carbon steel schedule at some sizes. Where a specification says 10S, supplying SCH 10 carbon-series wall is a dimensional non-conformance.
Yes, where the project specification permits it. A312 welded pipe is fully tested and code-acceptable for most service. Seamless is normally reserved for high-pressure, cyclic and sour-service lines.
Yes. Kalp Alloys manufactures to ASTM A312 at its own facility at 5, Jay Vijay Industrial Estate, B/h. Akash Vikas Estate, Keval Kanta Road, Rakhial, Ahmedabad, and issues the EN 10204 3.1 or 3.2 mill test certificate in its own name rather than passing through a third-party mill certificate.
An EN 10204 3.1 mill test certificate as standard, stating the ordered standard, grade and heat number, with chemical and mechanical results and a dimensional inspection report. EN 10204 3.2 with third-party inspection by SGS, BV, TUV or Lloyds is arranged where the project requires it.