SS 321 Pipe & TubeASTM A312 TP321 · Manufacturer, trader & exporter, India
Also sold as AISI 321 · UNS S32100 · W.Nr 1.4541 · Titanium-stabilised stainless
SS 321 pipe is supplied seamless to ASTM A312 TP321 and welded to ASTM A312 · A358, in ASME pipe sizes and schedules, with tube to ASTM A213. It is a titanium-stabilised austenitic stainless steel, chosen for high-temperature service between 425 and 815 °C. Kanak Steel & Engineering Co. manufactures, trades and exports it from Mumbai; EN 10204 3.1 or 3.2 certificates are available on request / as specified in the PO. Markets we have supplied to include Oman, UAE, Saudi Arabia, Brazil, Argentina, Spain and Chile (India is the home market).
- Stock & mill supply
- EN 10204 3.1 / 3.2
- PMI on request
- Export packing
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is SS 321 Pipe & Tube?
SS 321 pipe & tube is a titanium-stabilised austenitic stainless steel supplied as pipe & tube to ASTM A312 TP321 (UNS S32100). Buyers specify it for high-temperature service between 425 and 815 °C. It is also sold as AISI 321, UNS S32100, W.Nr 1.4541.
- What it is
- Titanium-stabilised austenitic stainless steel
- Seamless
- ASTM A312 TP321
- Welded
- ASTM A312 · A358
- Sizes
- NPS ⅛" – 24" · OD tube to order
- Schedules
- 5S · 10S · 40S · 80S · 160 · XXS
- Best at
- High-temperature service between 425 and 815 °C
SS 321 Pipe & Tube Specification & Sizes
| Seamless pipe | ASTM A312 TP321 |
|---|---|
| Welded pipe | ASTM A312 · A358 |
| Tube | ASTM A213 |
| Grade | SS 321 · UNS S32100 · S32109 (321H) · W.Nr 1.4541 |
| Size & schedule | NPS ⅛" to 24" to ASME B36.19 / B36.10; OD × wall for tube |
| Length | Single random, double random, or cut lengths |
| Ends | Plain end · bevelled end (for welding) · threaded |
| Testing | Hydrostatic or eddy-current · PMI · flattening & flaring · IGC on request |
| Documents | EN 10204 3.1 · 3.2 with third-party inspection |
SS 321 Pipe: Seamless, Welded or Tube?
Three different specifications cover 321 tubular products. Pick the route first — it decides price, test requirements and lead time. General requirements (tolerances, hydrostatic or electric testing) come from ASTM A999. Schedules, the −12.5% wall tolerance and the B31.3 wall formula are explained in the pipe guide.
| Route | Specification | Use it for |
|---|---|---|
| Seamless pipe | ASTM A312 TP321 | Pressure and critical service; no weld seam to inspect. |
| Welded pipe | ASTM A312 · A358 | Economical in larger diameters and thinner walls where the code allows it. |
| Tube | ASTM A213 | Heat exchangers and instruments; ordered by exact OD × wall. |
SS 321 Pipe Wall & Weight by Schedule
For the same size, the schedule sets the wall — and the weight you pay for. Cross-sections are drawn to scale for 2" NPS (OD 60.33 mm, ASME B36.19); weights use the density of SS 321, 7.92 g/cm³.
Other sizes: pipe schedule chart and weight calculator.
SS 321 Pipe & Tube Chemical Composition
Under technical review for TDS.
| Element | Current requirement |
|---|---|
| Chromium | As specified |
| Nickel | As specified |
| Titanium | As specified |
| Carbon | As specified |
| Manganese | As specified |
| Silicon | As specified |
| Nitrogen | As specified |
| Phosphorus | As specified |
| Sulphur | As specified |
| Iron | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification to be verified: ASTM A240 for UNS S32100.
SS 321 Pipe & Tube Mechanical Properties
Under technical review for TDS.
| Property | Current requirement |
|---|---|
| Tensile strength | As specified |
| Yield strength 0.2% | As specified |
| Elongation | As specified |
| Hardness | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification and condition to be verified: ASTM A240 for UNS S32100 — Annealed plate & sheet.
Density & Physical Properties
| Property | Value |
|---|---|
| Density | 7.92 g/cm³ |
| Melting range | 1400 – 1425 °C |
| Magnetic | Non-magnetic annealed |
| PREN (approx.) | ≈ 18 |
SS 321 Equivalent Grades
SS 321 Pipe Weight Chart (kg/m)
Weight per metre (kg/m) = (OD − WT) × WT × 0.02488, with OD and wall thickness in mm. The factor comes from SS 321's density of 7.92 g/cm³.
Example: 4" Sch 40S (114.30 × 6.02 mm)
(114.30 − 6.02) × 6.02 × 0.02488 = 16.22 kg/m
| NPS | OD mm | Sch 10S kg/m | Sch 40S kg/m |
|---|---|---|---|
| ½" | 21.34 | 1.01 | 1.28 |
| 1" | 33.40 | 2.11 | 2.52 |
| 2" | 60.33 | 3.97 | 5.49 |
| 3" | 88.90 | 6.52 | 11.39 |
| 4" | 114.30 | 8.44 | 16.22 |
| 6" | 168.28 | 13.95 | 28.51 |
| 8" | 219.08 | 20.14 | 42.92 |
Six-digit Harmonized System heading (iron and steel, chapter 72–73). Your country adds its own digits — confirm with your customs broker. All HS codes.
How to Verify SS 321 Pipe & Tube with PMI
Positive material identification with a handheld XRF gun confirms the alloy on the piece itself, in seconds, before it is cut or welded. SS 321 is most often mixed up with SS 347 — the table shows which elements tell them apart.
Handheld XRF does not measure carbon or nitrogen; those come from the mill certificate or optical emission (OES) testing. PMI can be arranged on request — state it on your enquiry.
Under technical review for TDS.
| Element | SS 321 | SS 347 |
|---|---|---|
| Nickel | As specified | As specified |
| Chromium | As specified | As specified |
| Titanium | As specified | — |
| Niobium | — | As specified |
| Iron | As specified | As specified |
| Manganese | As specified | As specified |
SS 321 Pipe & Tube Price — What Decides It
Two quotes for "321 pipe & tube" can differ by 20% and both be fair. We quote 321 pipe & tube per kg for full sizes and per piece for cut sizes. These six things move the price per kg, so you can compare offers like for like.
SS 321 Pipe & Tube Applications
SS 321 is specified when the cheaper grade will not survive the service but a higher alloy would be more than the job needs. These are the jobs our buyers use it for.
SS 321 Pipe & Tube vs 304, 347 and 310S
| Grade | Pipe & Tube standard | PREN (approx.) | Pick it when |
|---|---|---|---|
| SS 304 | ASTM A312 TP304 | ≈ 18 | General corrosion resistance, food, water and architectural work |
| SS 347 | ASTM A312 TP347 | ≈ 18 | Welded high-temperature piping in refineries and power plants |
| SS 321 | ASTM A312 TP321 | ≈ 18 | High-temperature service between 425 and 815 °C |
| SS 310 / 310S | ASTM A312 TP310S | ≈ 25 | Furnaces, burners and heat treatment at high temperature |
PREN = Cr + 3.3 Mo + 16 N, from mid-range chemistry. A screening guide, not a substitute for corrosion data on your medium.
SS 321 Corrosion Resistance — Element by Element
Each alloying addition has a job. Knowing which one protects against your medium is the quickest way to judge whether 321 fits.
About 18% chromium forms the passive film that makes the steel stainless.
Nickel keeps the structure austenitic — tough at low temperature and easy to form and weld.
Titanium ties up carbon, so 321 keeps its corrosion resistance after long service in the sensitising range.
321H with higher carbon is used above about 540 °C for better creep strength.
How your 321 pipe & tube order runs
- 01Enquiry review — we confirm size, standard edition and documents against your MR or drawing.
- 02Heat selection & PMI — the mill certificate is checked against your order; PMI can be arranged depending on product and requirements, as specified in the PO.
- 03Processing — cutting, machining or bevelling to your specification, with heat numbers marked as specified in the PO.
- 04Inspection — your third-party inspector witnesses, or we share photos and test reports.
- 05Packing & dispatch — seaworthy packing from Nhava Sheva (JNPT), Mumbai, FOB or CIF, documents sent before the vessel sails.
Standards on this page
Welding & Fabricating SS 321 Pipe & Tube
SS 321 welds by all common arc processes. A few points our buyers ask about:
| Matching filler | ER347 (AWS A5.9) |
|---|---|
| Over-alloyed filler | ER321 is rare; ER347 is the usual filler |
| Preheat | Not required; keep interpass temperature low |
| Cutting | Thermal or abrasive cutting; grind off heat-tinted edges before welding |
Follow your approved WPS; this is general guidance. See also 321 fittings and 321 flanges for the matching pipe-system parts.
How to Order SS 321 Pipe & Tube: RFQ Checklist
Get an accurate quote the first time. Copy this list into your enquiry:
- Seamless or welded, and the standard
- NPS and schedule (or OD × wall for tube)
- Length — random or cut, and number of lengths
- End finish — plain, bevelled or threaded
- Certificate type and extra tests
- Delivery port, Incoterm and required date
SS 321 pipe & tube — questions buyers ask
Is SS 321 the same as AISI 321?
AISI 321, UNS S32100, W.Nr 1.4541 are names used for SS 321 (W.Nr / EN numbers and older UNS variants are the closest designations; their limits can differ slightly, so specify the UNS number and ASTM grade on the order), and pipe & tube is ordered to ASTM A312 TP321 whichever name is on the enquiry.
What is the difference between SS 321 pipe and tube?
Pipe is ordered by nominal pipe size and schedule, for carrying fluids. Tube is ordered by exact outside diameter and wall, for heat exchangers and instruments, and is held to tighter tolerances.
Seamless or welded SS 321 pipe — which should I buy?
Seamless (ASTM A312 TP321) is the default for pressure and critical service. Welded (ASTM A312 · A358) is cheaper in larger diameters and thinner walls and is accepted where the design code allows it.
What is the wall-thickness tolerance on SS 321 pipe?
Seamless pipe is normally allowed −12.5% on nominal wall under its general-requirements standard (ASTM A999). Allow for it in the pressure calculation or order on minimum wall.
Can SS 321 pipe be welded to carbon-steel pipe?
Yes, with the right filler: ER309L (or E309L electrode) is the usual filler when joining it to carbon steel. Follow a qualified WPS.
SS 321 or SS 310 / 310S — which should I choose?
SS 321 is chosen for high-temperature service between 425 and 815 °C. SS 310 / 310S is the step up when you need more pitting resistance or strength. See the comparison table on this page, or ask us with your process conditions.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026