Article
ASTM A312 is the main specification for seamless, straight-seam welded and heavily cold worked austenitic stainless steel pipe for high-temperature and general corrosive service. If an enquiry asks for "SS pipe", it almost always means A312.
Construction types
- Seamless (SMLS) – made by piercing a solid billet and hot or cold finishing. Preferred for high pressure and critical lines.
- Welded (WLD) – formed from strip or plate and welded longitudinally without filler metal (or with, depending on process), then heat treated.
- Heavily cold worked (HCW) – welded pipe that is cold worked to refine the weld structure.
Common grades
| Grade | UNS | Typical use |
|---|---|---|
| TP304 / TP304L | S30400 / S30403 | Water, food, general process |
| TP304H | S30409 | High-temperature strength |
| TP316 / TP316L | S31600 / S31603 | Chlorides, chemicals, marine |
| TP316Ti | S31635 | Stabilised 316 for high temperature |
| TP317L | S31703 | Stronger chemicals, higher Mo |
| TP321 / TP347 | S32100 / S34700 | Stabilised, 425–815 °C |
| TP309S / TP310S | S30908 / S31008 | Oxidation and heat resistance |
| TP904L | N08904 | Sulphuric acid, severe chlorides |
Sizes and schedules
A312 pipe is ordered to ASME B36.19M dimensions, using stainless schedules 5S, 10S, 40S and 80S, or B36.10M schedules such as SCH 160 and XXS for heavier walls. Typical sizes run from 1/8" to 24" and above; larger sizes are often welded.
Mandatory tests
- Chemical analysis per heat
- Tensile test (and flattening test for most sizes)
- Hydrostatic test or non-destructive electric test (eddy current or ultrasonic) on every length
- Solution annealing and visual and dimensional inspection
Writing an A312 enquiry
Pipe 3" SCH 40S, ASTM A312 TP316L, seamless, ASME B36.19M, 6 m random length, plain ends, pickled, EN 10204 3.1 – 300 m
Include grade, construction, size, schedule, length, end finish, surface condition, certificate type and quantity in metres or lengths.
Frequently asked questions
What is ASTM A312 used for?
It covers seamless and welded austenitic stainless steel pipe for high-temperature and general corrosive service.
What does TP mean in TP316L?
TP stands for "type", indicating the stainless grade, here type 316L.
Is every A312 pipe hydrotested?
Every length must pass either a hydrostatic test or a non-destructive electric test such as eddy current.
Key takeaways
- A312 is the standard for austenitic stainless pipe.
- Specify seamless or welded clearly.
- Give grade, size, schedule, length, ends, finish and certificate.
Need these products?
Sawariya Metal Industries supplies stainless steel pipes, flanges and buttweld pipe fittings from Mumbai to buyers in India and overseas. Send your size, grade, standard and quantity through our enquiry form and we will reply with a clear quotation and the test documents you need. You can also browse our stainless steel pipes, flanges and buttweld fittings.