TP309 Seamless Stainless Steel Pipe
At a glance — TP309 Pipe
| Specification | ASTM A312 — the edition cited on the PO governs |
| Ordering basis | NPS × schedule, or OD × wall — stated on the order |
| Sourcing range | OD 6 – 1016 mm · wall 0.5 – 65 mm · length ≤ 18 m; each standard × OD × wall × length × condition confirmed in writing |
| Condition | Solution annealed; pickled & passivated, bright annealed or polished |
| Documents | EN 10204 3.1 MTC as standard (3.2 on request); hydrostatic or NDT electric test on every length |
Sourcing capability, not a stock list — availability, MOQ and lead time are stated in the written quotation.
Grade note — TP309 (UNS S30900) has been withdrawn from the current editions of ASTM A213 and A312 and can no longer be ordered as a TP grade. The data on this page are for TP309S (UNS S30908), the low-carbon grade currently produced for this duty. For creep-limited service, the high-carbon variant is TP309H (UNS S30909).
Sizes, Wall Basis and Ordering
Two figures are kept apart here: the overall sourcing range — what we can supply ex-stock or source mill-direct — and the confirmed combination for your order (standard × size × wall × length × condition). The tables state the first; the written quotation fixes the second.
Supply combinations by size band
| Size band, mm (NPS) | Wall range, mm | Supply route (ex-stock / mill-direct) | Order status |
|---|---|---|---|
| ≤ 25 | 2.0 – 5.0 | Ex-stock · standard walls | In stock · 3–7 days |
| > 25 – 114.3 | 2.5 – 12.0 | Ex-stock; mill-direct above 6 mm wall | In stock / mill-direct |
| > 114.3 – 323.9 | 3.5 – 30.0 | Mill-direct | Mill-direct · 25–35 days |
| > 323.9 – 610 | 6.0 – 50.0 | Mill-direct | Mill-direct · 25–35 days |
| > 610 – 1016 | 8.0 – 65.0 | Mill-direct | Mill-direct · 25–35 days |
Stock items are marked In stock; everything else is mill-direct with a stated lead time. Schedule coverage follows the wall range shown for each band; non-standard walls are quoted individually. Above NPS 24 the tabulated dimensional bands no longer apply and the basis is agreed in writing.
Ordering options
| Item | What can be ordered |
|---|---|
| Size | NPS and schedule, or actual OD × wall thickness |
| Outside diameter | 6 – 1016 mm — to the ordered OD or to the NPS dimension |
| Wall thickness | 0.5 – 65 mm — schedule wall or specified wall, stated on the order |
| Length | Random 5.8–7 m (single or double random), fixed up to 18 m |
| Ends | Plain, bevelled, or threaded with couplings |
| Surface | Pickled and passivated, or shot-blasted |
| Delivery condition | Solution annealed; hydrostatic or NDT route per specification |
Sizes at the edge of a band are quoted after technical review. If your enquiry is written in NPS and schedule, the quotation restates it as OD × wall so our desk and your buying team are working from the same numbers.
Ordering Standards: A312 vs A213
A312 is the pipe specification and the one this page describes: the pipe is ordered by NPS and schedule and every length carries an integrity test. A213 is the tube specification, which uses OD and wall rather than NPS; it is quoted only when the line is dimensioned that way. Duplex pipe follows A790 and tube follows A789 — the grade is the same, the dimensional and test clauses are not.
| Item | ASTM A312 | ASTM A213 |
|---|---|---|
| Scope | Seamless and welded pipe for pressure and corrosive service | Tube for heat transfer and pressure parts |
| Ordering basis | NPS × schedule, or OD × wall | OD × wall × length, no NPS |
| Wall basis | Nominal wall with the standard tolerances | Minimum or average wall, stated on the order |
| Testing | Integrity test per length; NDT level as agreed | Integrity test per length, plus flattening or flare |
| Typical use | Process and transfer lines, piping spools | Heat exchangers, condensers, boilers |
A312 and A790 are the two pipe specifications that matter for this grade family; A213 and A789 cover the tube form. Nickel alloys follow the B-series pipe specifications (B619, B725, B165 and the matching part of each alloy's standard) — state the exact specification and edition.
Chemical Composition (TP309S Heat-Analysis Limits)
Chemical composition, % by weight:
| Cr | Ni | Mn | Si | P | S | Fe | C |
|---|---|---|---|---|---|---|---|
| 22.00–24.00 | 12.00–15.00 | ≤ 2.00 | ≤ 0.75 | ≤ 0.045 | ≤ 0.030 | Bal | ≤ 0.08 |
Values are the heat-analysis limits of the specification named above. Product analysis on the finished tube or pipe may differ within the tolerances the standard permits, and the actual heat analysis is printed on the mill test certificate.
Mechanical Properties and Physical Data
Mechanical properties:
| Tensile Strength | Yield Strength | Elongation | Hardness |
|---|---|---|---|
| ≥ 515 MPa | ≥ 205 MPa | ≥ 35% | ≤ 192 HBW |
Typical physical properties:
| Density | Melting Point | Thermal Expansion | Thermal Conductivity | Modulus of Elasticity | Electrical Resistivity |
|---|---|---|---|---|---|
| 7.9 g/cm³ | 1400–1450 °C approx. | 16.5 µm/m·°C (20–100°C) | 14.2 W/m·K (20°C) | 200 GPa | 0.78 x 10⁻⁶ Ω·m (20°C) |
Tensile and yield values are specification minima at room temperature; hardness and grain size are reported when the purchase order asks for them. Design values at service temperature must be taken from the applicable code, not from this table.
Permissible Variations in Dimensions (A312)
Dimensional acceptance follows A999/A999M for A312 pipe and the corresponding tables of A790 for duplex. The bands below are representative; the edition cited on the purchase order governs, and measured values are recorded on the mill test certificate.
Outside diameter
| NPS | Permissible variation |
|---|---|
| 1/8 – 1 1/2 | + 0.4 / − 0.8 mm |
| 2 – 4 | + 0.4 / − 0.8 mm |
| 5 – 8 | + 0.8 / − 0.8 mm |
| 10 – 18 | + 1.6 / − 0.8 mm |
| 20 – 24 | + 2.4 / − 0.8 mm |
| > 24 – 40 | Agreed in writing |
The variation applies to the individual measurement. For bored pipe the wall is measured at the ends as well as mid-length.
Wall thickness
| Condition | Permissible variation |
|---|---|
| Seamless, t/D ≤ 5 % | + 20 % / − 12.5 % of nominal wall |
| Seamless, t/D > 5 % | + 22.5 % / − 12.5 % of nominal wall |
| Minimum wall ordered | No point below the ordered minimum |
Where the design uses a minimum wall, the order must say so; a nominal-wall order does not guarantee the minimum the calculation assumed.
Random lengths 5.8–7 m single random, 11–13 m double random, unless a fixed length is ordered. End squareness and bevel angle are inspected before packing.
Inspection, Testing and Mill Test Certificates
Three groups of evidence are separated here, because only the first is inside the base price. Anything in the second and third groups has to be written on the purchase order — it cannot be added after the mill test certificate has been issued.
| Group | Content | How it is triggered |
|---|---|---|
| 1 — Included | Chemical analysis, tensile test, flattening or bend test, hydrostatic or nondestructive electric test, dimensional check, EN 10204 3.1 certificate | Standard supply; no extra instruction needed |
| 2 — Written on the PO | Ultrasonic or eddy-current testing to a stated acceptance level, PMI on each heat, intergranular corrosion test, grain size, hardness survey, 3.2 certificate | Must appear on the purchase order; priced per order |
| 3 — Third party | TPI witness (SGS, BV, TÜV, Lloyd's), destructive sampling, third-party laboratory, packing inspection, pre-shipment photographs | Arranged per order; extends the lead time |
The test route is not interchangeable after the fact: if the certificate has to show ultrasonic testing, say so on the enquiry, because a hydrostatic-only pipe cannot be re-certified as ultrasonically tested.
What the mill test certificate records
| Heat number | The melt the item came from, traceable to the raw-material certificate |
| Grade and specification | Grade designation plus the standard and edition the order cites |
| Chemical analysis | Actual values for each element, not the range |
| Mechanical results | Tensile, yield, elongation and hardness as tested |
| Test route | Hydrostatic or nondestructive electric test, plus any agreed NDT with the method reference |
| Heat treatment | Solution-annealing temperature range and cooling method |
| Dimensions | Ordered OD, wall and length, with the measured values on request |
TP309 Pipe Applications and Points to Confirm
Each application below names the duty the grade is normally chosen for, and what should be settled before the order is placed — the third column decides whether this grade is the right one:
| Industry | Typical duty |
|---|---|
| Industrial furnaces | furnace and kiln duty |
| Power generation | boiler, superheater and feedwater duty |
| Petrochemical & refining | hydrocarbon and sour-service duty |
| Chemical processing | aggressive reaction and transfer duty |
| Cement & lime | dusty, alkaline kiln duty |
| Automotive | exhaust and thermal-cycle duty |
Points to confirm before ordering
- Medium, concentration and chloride content — the figures that decide whether this grade holds
- Design temperature and pressure, including upset and cleaning cycles
- Whether the joint is welded, and the post-weld condition required
- Inspection and document scope: NDT level, PMI, third-party witness
Send the medium, concentration, temperature, pressure and chloride level, and we will confirm the grade — or propose the next one up if the margin is narrow.
Grade Selection: TP309 vs TP310
| Property | TP309 | TP310 |
|---|---|---|
| PREN, typical | 22 | 25 |
| Molybdenum | — | — |
| Yield strength, min. | ≥ 205 MPa | ≥ 205 MPa |
| Service temperature | ≈ 1000 °C | ≈ 1100 °C |
| Choose when | General corrosion service, welded assemblies, cost-sensitive projects | Lower alloy content is enough for the duty |
PREN is indicative only and is calculated from the composition ranges above — it is not an acceptance value. Where the duty sits between two grades, the deciding factors are usually chloride content, temperature and whether the joint is welded.
Frequently Asked Questions
What sizes can be supplied in TP309 pipe?
The overall sourcing range is OD 6 – 1016 mm, wall 0.5 – 65 mm, length 18 m. The band table shows the wall range normally held or supplied for each OD band; the exact combination of standard, OD, wall, length and manufacturing condition is confirmed in the quotation. Sizes at the edge of a band are quoted after technical review.
Is this page a stock list?
In part. Stocked sizes are marked In stock and ship in 3–7 days; everything else is mill-direct with a 25–35 day lead time, confirmed per item in the quote.
Is TP309 pipe ordered by NPS or by outside diameter?
Either, but it must be clear. NPS with schedule is the usual purchase form for process piping; actual OD × wall is used when the line is dimensioned that way. The quotation restates the order in both notations so our desk and your buying team are working from the same numbers.
Which specification applies — A312 or A213?
ASTM A312 is the primary specification for this pipe and the one the page describes. ASTM A213 is the adjacent specification; whether it applies depends on the ordered form, the test regime and the design code. State the standard and edition on the enquiry and the certificate will cite the same one.
Which tests and documents are included?
Mandatory: one integrity test per length (hydrostatic or nondestructive electric), tensile test per lot, dimensional check and an EN 10204 3.1 mill test certificate. Optional and only when written on the order: ultrasonic or eddy-current testing to a stated level, PMI, intergranular corrosion test, grain size, third-party witness and 3.2 certification.
How does TP309 compare with TP310?
TP310 is the usual comparison grade. TP309 carries PREN of about 22 against 25 for TP310, with a minimum yield of 205 MPa. The change is normally made when the duty — chloride level, temperature or pressure — leaves TP310 without margin over the design life.
Request a TP309 Pipe Quotation
Send: specification and edition, OD or NPS, wall and wall basis, length, quantity, surface finish, inspection scope and documents, and destination port. The quotation will restate the confirmed size combination, delivery condition, documents included and lead time for TP309 Pipe.
Related Product Forms and Grades
Other forms and neighbouring grades, each with its own specification — confirm the applicable standard on every order:
- TP309 seamless tube — UNS S30908 · W-Nr 1.4833
- TP310 seamless pipe — TP310 — the grade normally compared with TP309 on this duty
- Contact the sales team — Sizes outside the range, non-standard lengths and third-party inspection
Technical data compiled from the ASTM/ASME specification tables cited above and from published mill data. Page reviewed by the Xinzhe technical team, 09–11-2026. All values must be confirmed against the edition current at the time of order and against the heat certificate.
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