Stainless Steel Seamless Pipes
Giriraj Impex stocks, supplies and exports stainless steel seamless pipes to ASTM A312 / ASME SA312 in grades TP304, TP304L, TP316, TP316L, TP321, TP347 and TP310S. Our stainless steel seamless pipes are sourced from approved mills in nominal sizes from ½" to 24" NB (DN 15 to DN 600) and in schedules from 5S to XXS, solution annealed and pickled, and supplied with mill test certificates.
Seamless stainless pipe is used for corrosive process fluids at high pressure and temperature – in refineries, chemical and pharmaceutical plants, fertiliser units, power stations and food processing lines – wherever a design code or client specification calls for pipe without a weld seam.
Specifications
| Item | Details |
|---|---|
| Product standard | ASTM A312 / ASME SA312 (seamless) |
| Dimensional standard | ASME B36.19M; heavier walls to ASME B36.10M |
| Size range | ½" to 24" NB (DN 15 to DN 600) |
| Schedules | 5S, 10S, 40S, 80S; SCH 10 to 160, STD, XS and XXS |
| Grades | TP304, TP304L, TP304H, TP316, TP316L, TP316Ti, TP321, TP347, TP310S |
| Production route | Hot finished or cold finished (cold drawn or pilgered) |
| Heat treatment and finish | Solution annealed; pickled and passivated; bright annealed on request |
| Lengths | Single random, double random and cut lengths |
| Ends | Plain end, bevelled end to ASME B16.25, threaded |
| Documents | Mill test certificate (MTC); third-party inspection on request |
Outside diameters and wall thicknesses for each size and schedule are listed in our pipe schedule chart.
Grades available
| Grade | UNS | When it is used |
|---|---|---|
| TP304 / 304L | S30400 / S30403 | General corrosion resistance, food, water and mild chemicals |
| TP316 / 316L | S31600 / S31603 | Chlorides, seawater, many acids and pharmaceutical service |
| TP321 | S32100 | Titanium stabilised for intermittent heating in the 425–815 °C range |
| TP347 | S34700 | Niobium stabilised alternative to 321 |
| TP304H | S30409 | Higher carbon for strength at high temperature |
| TP310S | S31008 | Oxidation resistance at high temperature |
For a full description of each grade see the stainless steel material page.
Chemical composition and mechanical properties
The tables below show the ASTM A312 requirements for the most frequently ordered grades. Actual values for each heat are given on the mill test certificate.
| 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.
Testing, marking and packing
ASTM A312 requires each length of pipe to pass either a hydrostatic test or a non-destructive electric test, together with tensile, flattening and chemical tests on samples from each lot. Supplementary tests such as intergranular corrosion testing to ASTM A262 Practice E, ultrasonic examination or a hydrostatic test in addition to the electric test can be added to the order. Pipes are marked along the length with the mill's name or brand, specification, grade, size, schedule, heat number and "SMLS". Ends are protected with plastic caps, and pipes are bundled or packed in wooden boxes for export.
Applications
Stainless steel seamless pipes carry corrosive and high-purity fluids in chemical and petrochemical plants, refineries, fertiliser and pharmaceutical units, dairy and food processing, power generation, desalination and marine systems. Smaller sizes are used for instrument, sampling and hydraulic lines, and larger sizes for process headers. For larger diameters or lower-pressure duties, stainless steel welded pipes are an alternative; for heat-exchanger and instrument service see stainless steel tubes.
Both seamless and welded options are quoted on request.
Hot finished or cold finished?
ASTM A312 seamless pipe can be hot finished or cold finished. Hot-finished pipe is rolled or extruded to size at high temperature and is common in larger diameters and heavy walls. Cold-finished pipe is cold drawn or pilgered after hot piercing, giving closer dimensional tolerances, a smoother surface and thinner walls, and is usual in small and medium sizes. Both are solution annealed. If your specification requires one route, state it on the order; otherwise the mill's standard route for the size is supplied.
Stainless steel in other product forms
To complete a stainless steel piping package, we also supply stainless steel flanges, pipe fittings and fasteners in the same grades, together with plates, sheets, coils, round bars, wires, circles, rings, angles, channels and flats. All seamless forms are listed on the seamless pipes and tubes page.
Frequently Asked Questions
ASTM A312 (ASME SA312 in the ASME Boiler and Pressure Vessel Code) covers seamless, welded and heavily cold-worked austenitic stainless steel pipe for high-temperature and general corrosive service. Dimensions follow ASME B36.19M.
We supply seamless pipes from ½" to 24" NB (DN 15 to DN 600) in schedules 5S, 10S, 40S and 80S, and heavier schedules up to XXS where required. Availability for each size and schedule is confirmed with the quotation.
Often, yes. Material meeting the low-carbon limit of TP316L and the strength requirements of TP316 can be certified to both grades, which is shown on the mill test certificate as TP316/316L.
Pickling removes the oxide scale formed during annealing, and passivation restores the protective chromium oxide film on the surface. Together they give the clean surface needed for full corrosion resistance.
Yes. Intergranular corrosion testing to ASTM A262 Practice E can be added as a supplementary requirement. Please state it in your enquiry along with any other tests and inspection required.
Yes. Pipes are supplied in single random, double random or cut lengths as ordered. Please state the required length and tolerance, and the end preparation, in your enquiry.
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