SS 304 Pipes (304 / 304L)
Giriraj Impex stocks, supplies and exports SS 304 pipe and SS 304L pipe to ASTM A312 / ASME SA312 grades TP304 and TP304L, in seamless and welded construction. We supply SS 304 pipes from approved mills in sizes from ½" to 24" NB in schedules 5S, 10S, 40S and 80S and heavier walls, solution annealed and pickled, dual certified TP304/304L where required, with mill test certificates.
SS 304 pipe is the general-purpose stainless pipe for fresh water, food and beverage, dairy, pharmaceutical utilities, mild chemicals and architectural use – wherever corrosion resistance is needed but chlorides are low. For chloride or seawater exposure, SS 316 pipe is the usual step up.
Specifications
| Item | Details |
|---|---|
| Standard | ASTM A312 / ASME SA312 |
| Grades | TP304 (S30400), TP304L (S30403), dual certified TP304/304L; TP304H on request |
| Construction | Seamless (SMLS) or welded (WLD) |
| Sizes | ½" to 24" NB (DN 15 to DN 600); larger welded sizes on request |
| Schedules | 5S, 10S, 40S, 80S; SCH 160 and XXS from ASME B36.10M |
| Dimensions | ASME B36.19M and B36.10M |
| Finish | Annealed and pickled; polished on request |
| Ends | Plain, bevelled, threaded |
| Documents | Mill test certificate (MTC); third-party inspection on request |
Chemical composition and mechanical properties
The ASTM A312 requirements for TP304 and TP304L are shown with those of TP316/316L for comparison.
| Grade | UNS | C | Mn | P | S | Si | Cr | Ni | Mo |
|---|---|---|---|---|---|---|---|---|---|
| TP304 | S30400 | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 18.0–20.0 | 8.0–11.0 | – |
| TP304L | S30403 | 0.035 | 2.00 | 0.045 | 0.030 | 1.00 | 18.0–20.0 | 8.0–13.0 | – |
| TP316 | S31600 | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 16.0–18.0 | 10.0–14.0 | 2.00–3.00 |
| TP316L | S31603 | 0.035 | 2.00 | 0.045 | 0.030 | 1.00 | 16.0–18.0 | 10.0–14.0 | 2.00–3.00 |
Other elements and footnotes as given in the standard. Dual-certified material meets both grades.
| Grade | Tensile strength, MPa (ksi) | Yield strength, MPa (ksi) | Elongation in 50 mm, % (longitudinal) |
|---|---|---|---|
| TP304 | 515 (75) | 205 (30) | 35 |
| TP304L | 485 (70) | 170 (25) | 35 |
| TP316 | 515 (75) | 205 (30) | 35 |
| TP316L | 485 (70) | 170 (25) | 35 |
Transverse elongation and other requirements as given in the standard.
For the grade's background, equivalents and physical properties see SS 304 / 304L.
Seamless or welded SS 304 pipe
Both forms are made to the same A312 grade requirements. Seamless stainless pipes are chosen for higher pressures, critical process lines and where specifications exclude welded pipe; they are common up to medium sizes. Welded stainless pipes are more economical, especially in thin walls (5S and 10S) and larger diameters, and are widely used for water, utility, food and architectural lines. Pipes are marked SMLS or WLD so the form can be identified.
Why choose 304L for welded lines
In standard-carbon 304, the heat of welding can precipitate chromium carbides at grain boundaries next to the weld, leaving a zone that is open to intergranular corrosion. The 0.035% maximum carbon of TP304L in ASTM A312 largely prevents this, so 304L is the normal choice for site-welded piping. Dual-certified TP304/304L pipe meets both the low carbon of 304L and the higher minimum strength of 304, so it satisfies specifications calling for either grade. Where the pipe will run hot for long periods, TP304H, with controlled higher carbon, is used instead.
Equivalent designations
| Grade | UNS | EN number | EN name | JIS | BS |
|---|---|---|---|---|---|
| 304 | S30400 | 1.4301 | X5CrNi18-10 | SUS304 | 304S31 |
| 304L | S30403 | 1.4307 | X2CrNi18-9 | SUS304L | 304S11 |
| 316 | S31600 | 1.4401 | X5CrNiMo17-12-2 | SUS316 | 316S31 |
| 316L | S31603 | 1.4404 | X2CrNiMo17-12-2 | SUS316L | 316S11 |
Equivalent grades are similar but not identical; composition and property limits differ between standards. Order to the standard you need.
Testing, marking and ordering
Each length is hydrostatically or electrically tested as A312 requires, with flattening and tensile tests on samples, and marked with grade, size, schedule, heat number and SMLS or WLD. Intergranular corrosion testing to ASTM A262 Practice E can be added. Please give the grade, seamless or welded, size, schedule, length, end finish, quantity and any supplementary tests or inspection.
Applications and related products
SS 304 pipes are used for potable and process water, dairy and beverage plants, food processing, pharmaceutical utilities, compressed air and gases, heat exchangers in clean service, architectural handrails and structures, and general engineering. They are installed with SS 304 fittings and flanges; for flat material in the same grade see SS 304 sheets and plates, and for bar see SS 304 round bars. Other seamless and welded materials are on the seamless pipes and tubes and welded pipes and tubes pages.
Frequently Asked Questions
ASTM A312 (ASME SA312) covers seamless and welded austenitic stainless steel pipe, including grades TP304 and TP304L. Dimensions follow ASME B36.19M.
TP304L has a lower maximum carbon content (0.035% against 0.08% in ASTM A312), which prevents sensitisation at welds. Its minimum strength is slightly lower. Pipe is often dual certified TP304/304L.
Yes. SS 304 is widely used for potable water lines because it resists corrosion in fresh water and does not affect water quality. Where chloride levels are high, 316L is preferred.
We supply SS 304 pipe from ½" to 24" NB in schedules 5S, 10S, 40S and 80S and heavier walls, seamless or welded, with larger welded sizes on request.
No. SS 304 pits and suffers crevice corrosion in seawater. SS 316L, duplex or super duplex pipe is used for seawater service.
Yes. Welded SS 304 pipe can be supplied with polished external or internal surfaces for architectural and hygienic applications.
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