Stainless steel seamless tubes are chosen wherever a tube wall must hold pressure and heat with no weld line to inspect. The reason is simple. Under ASTM A213 for boiler, superheater and heat exchanger tubes, and ASTM A269 for general corrosion and instrumentation tubing, a seamless tube is credited with its full wall strength, while a welded tube may carry a joint factor and extra weld examination. Metinox Overseas supplies SS seamless tubes in austenitic grades, cold drawn and annealed, to buyers in India, the GCC and other export markets.
Contact us today for Stainless Steel Tubes in seamless and welded form, supplied to ASTM A213, A269 and EN 10216-5 to suit your specific industrial requirements.
Table of Contents
- Seamless Stainless Steel Tubing Specifications
- SS Tube Grades: UNS, EN, DIN and JIS Equivalents
- Chemical Composition of SS Seamless Tubes
- Mechanical Properties of ASTM A312M Stainless Steel Seamless Tubing
- Physical Properties of Austenitic Stainless Steel Tubing
- Stainless Steel Round Tube Size and Weight Chart (OD, BWG, kg/m)
- SS Seamless Tube Sizes by Wall Thickness
- Seamless vs ERW Stainless Steel Tube: Which to Specify
- Where Seamless Stainless Steel Tubing Is Used: Industry Applications
- Inspection and Testing of Stainless Steel Seamless Tubes
- Request a Quotation for Stainless Steel Seamless Tubes
- Stainless Steel Seamless Tube by Grade and Matching Products
- SS Seamless Tube Frequently Asked Questions
Seamless Stainless Steel Tubing Specifications
| Item | Detail |
|---|---|
| Product | Stainless steel seamless tube, cold finished |
| General requirements | ASTM A1016 / A1016M (tolerances, testing, marking) |
| Grades | TP304, TP304L, TP304H, TP316, TP316L, TP316H, TP316Ti, TP317L, TP321, TP321H, TP347, TP347H, TP310S |
| Outside diameter | 1/16 in (1.59 mm) to 4 in (101.6 mm) OD; other sizes to specification |
| Wall thickness | Specified as minimum wall (MW) or average wall (AW); BWG or mm |
| Length | Single random, double random, fixed cut length, U bend to drawing |
| Condition | Solution annealed and pickled, or bright annealed |
| Ends | Plain, square cut, deburred |
| Testing to the standard | Tension, flattening, flaring, hardness, hydrostatic or electric NDE per A1016 |
| Supplementary tests | Available on request where your specification calls for them: intergranular corrosion (ASTM A262 Practice E), eddy current, ultrasonic, PMI |
| Certification | EN 10204 3.1 mill test certificate with full heat traceability |
SS Tube Grades: UNS, EN, DIN and JIS Equivalents
| ASTM grade | UNS | EN number | DIN | JIS (tube) |
|---|---|---|---|---|
| TP304 | S30400 | 1.4301 | X5CrNi18-10 | SUS304TB |
| TP304L | S30403 | 1.4307 / 1.4306 | X2CrNi18-9 | SUS304LTB |
| TP304H | S30409 | 1.4948 | X6CrNi18-10 | SUS304HTB |
| TP316 | S31600 | 1.4401 | X5CrNiMo17-12-2 | SUS316TB |
| TP316L | S31603 | 1.4404 | X2CrNiMo17-12-2 | SUS316LTB |
| TP316Ti | S31635 | 1.4571 | X6CrNiMoTi17-12-2 | n/a |
| TP317L | S31703 | 1.4438 | X2CrNiMo18-15-4 | SUS317LTB |
| TP321 | S32100 | 1.4541 | X6CrNiTi18-10 | SUS321TB |
| TP347 | S34700 | 1.4550 | X6CrNiNb18-10 | SUS347TB |
| TP310S | S31008 | 1.4845 | X8CrNi25-21 | SUS310STB |
Chemical Composition of SS Seamless Tubes
| Grade | C | Mn | P | S | Si | Cr | Ni | Mo |
|---|---|---|---|---|---|---|---|---|
| TP304 | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 18.0 to 20.0 | 8.0 to 11.0 | - |
| TP304L | 0.035 | 2.00 | 0.045 | 0.030 | 1.00 | 18.0 to 20.0 | 8.0 to 12.0 | - |
| TP304H | 0.04 to 0.10 | 2.00 | 0.045 | 0.030 | 1.00 | 18.0 to 20.0 | 8.0 to 11.0 | - |
| TP316 | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 16.0 to 18.0 | 10.0 to 14.0 | 2.00 to 3.00 |
| TP316L | 0.035 | 2.00 | 0.045 | 0.030 | 1.00 | 16.0 to 18.0 | 10.0 to 14.0 | 2.00 to 3.00 |
| TP317L | 0.035 | 2.00 | 0.045 | 0.030 | 1.00 | 18.0 to 20.0 | 11.0 to 15.0 | 3.0 to 4.0 |
| TP321 | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 17.0 to 19.0 | 9.0 to 12.0 | - |
| TP347 | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 17.0 to 19.0 | 9.0 to 12.0 | - |
| TP310S | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 24.0 to 26.0 | 19.0 to 22.0 | 0.75 max |
Mechanical Properties of ASTM A312M Stainless Steel Seamless Tubing
| Grade | Tensile strength min, MPa (ksi) | Yield strength 0.2% min, MPa (ksi) | Elongation in 50 mm min, % | Hardness max |
|---|---|---|---|---|
| TP304, TP304H | 515 (75) | 205 (30) | 35 | 192 HBW / 90 HRB |
| TP304L | 485 (70) | 170 (25) | 35 | 192 HBW / 90 HRB |
| TP316, TP316H, TP316Ti | 515 (75) | 205 (30) | 35 | 192 HBW / 90 HRB |
| TP316L, TP317L | 485 (70) | 170 (25) | 35 | 192 HBW / 90 HRB |
| TP321, TP321H | 515 (75) | 205 (30) | 35 | 192 HBW / 90 HRB |
| TP347, TP347H | 515 (75) | 205 (30) | 35 | 192 HBW / 90 HRB |
| TP310S | 515 (75) | 205 (30) | 35 | 192 HBW / 90 HRB |
Physical Properties of Austenitic Stainless Steel Tubing
| Property | 304 / 304L | 316 / 316L | 321 | Unit |
|---|---|---|---|---|
| Density | 8.00 | 8.00 | 7.92 | g/cm³ |
| Elastic modulus | 193 | 193 | 193 | GPa |
| Mean thermal expansion, 20 to 100°C | 17.2 | 15.9 | 16.6 | µm/m·°C |
| Thermal conductivity at 100°C | 16.2 | 16.3 | 16.1 | W/m·K |
| Specific heat, 0 to 100°C | 500 | 500 | 500 | J/kg·K |
| Electrical resistivity | 0.72 | 0.74 | 0.72 | µΩ·m |
| Melting range | 1400 to 1450 | 1375 to 1400 | 1400 to 1425 | °C |
Stainless Steel Round Tube Size and Weight Chart (OD, BWG, kg/m)
Weight (kg/m) = 0.02491 x wall x (OD minus wall), both in mm, based on 304 density. 316 runs about 0.6% heavier.
| OD (mm) | OD (in) | Wall (mm) | BWG (wall, in) | Weight (kg/m) |
|---|---|---|---|---|
| 6.35 | 1/4 | 0.89 | 20 (0.035) | 0.12 |
| 6.35 | 1/4 | 1.24 | 18 (0.049) | 0.16 |
| 9.53 | 3/8 | 0.89 | 20 (0.035) | 0.19 |
| 9.53 | 3/8 | 1.24 | 18 (0.049) | 0.26 |
| 9.53 | 3/8 | 1.65 | 16 (0.065) | 0.32 |
| 12.70 | 1/2 | 0.89 | 20 (0.035) | 0.26 |
| 12.70 | 1/2 | 1.24 | 18 (0.049) | 0.35 |
| 12.70 | 1/2 | 1.65 | 16 (0.065) | 0.45 |
| 12.70 | 1/2 | 2.11 | 14 (0.083) | 0.56 |
| 15.88 | 5/8 | 1.24 | 18 (0.049) | 0.45 |
| 15.88 | 5/8 | 1.65 | 16 (0.065) | 0.58 |
| 15.88 | 5/8 | 2.11 | 14 (0.083) | 0.72 |
| 19.05 | 3/4 | 1.24 | 18 (0.049) | 0.55 |
| 19.05 | 3/4 | 1.65 | 16 (0.065) | 0.72 |
| 19.05 | 3/4 | 2.11 | 14 (0.083) | 0.89 |
| 19.05 | 3/4 | 2.77 | 12 (0.109) | 1.12 |
| 25.40 | 1 | 1.65 | 16 (0.065) | 0.98 |
| 25.40 | 1 | 2.11 | 14 (0.083) | 1.22 |
| 25.40 | 1 | 2.77 | 12 (0.109) | 1.56 |
| 25.40 | 1 | 3.40 | 10 (0.134) | 1.86 |
| 31.75 | 1 1/4 | 1.65 | 16 (0.065) | 1.24 |
| 31.75 | 1 1/4 | 2.11 | 14 (0.083) | 1.56 |
| 31.75 | 1 1/4 | 2.77 | 12 (0.109) | 2.00 |
| 38.10 | 1 1/2 | 1.65 | 16 (0.065) | 1.50 |
| 38.10 | 1 1/2 | 2.11 | 14 (0.083) | 1.89 |
| 38.10 | 1 1/2 | 2.77 | 12 (0.109) | 2.44 |
| 38.10 | 1 1/2 | 3.40 | 10 (0.134) | 2.94 |
| 50.80 | 2 | 1.65 | 16 (0.065) | 2.02 |
| 50.80 | 2 | 2.77 | 12 (0.109) | 3.31 |
| 50.80 | 2 | 4.19 | 8 (0.165) | 4.86 |
| 63.50 | 2 1/2 | 2.77 | 12 (0.109) | 4.19 |
| 63.50 | 2 1/2 | 4.57 | 7 (0.180) | 6.71 |
| 76.20 | 3 | 2.77 | 12 (0.109) | 5.07 |
| 76.20 | 3 | 4.57 | 7 (0.180) | 8.15 |
| 101.60 | 4 | 3.40 | 10 (0.134) | 8.32 |
| 101.60 | 4 | 6.35 | (0.250) | 15.07 |
Sizes outside these ranges can be made to order: send your size, schedule or class and quantity. Request a quote for Seamless SS Tubes
SS Seamless Tube Sizes by Wall Thickness
Instrument and heat exchanger tube sizes we quote most often, grouped by wall. Walls are BWG-aligned; metric walls are supplied to the same tolerance class.
| Wall thickness (mm) | Wall thickness (in) | Outside diameters available (in) |
|---|---|---|
| 0.25 | 0.010 | 1/16, 1/8, 3/16 |
| 0.51 | 0.020 | 1/16, 1/8, 3/16, 1/4, 5/16, 3/8 |
| 0.71 | 0.028 | 1/8, 3/16, 1/4, 5/16, 3/8, 1/2, 3/4, 1, 1 1/2, 2 |
| 0.89 | 0.035 | 1/8, 3/16, 1/4, 5/16, 3/8, 7/16, 1/2, 5/8, 3/4, 7/8, 1, 1 1/4, 1 1/2, 1 5/8, 2, 2 1/4 |
| 1.24 | 0.049 | 3/16, 1/4, 5/16, 3/8, 1/2, 5/8, 3/4, 7/8, 1, 1 1/8, 1 1/4, 1 1/2, 1 5/8, 2, 2 1/4 |
| 1.65 | 0.065 | 1/4, 5/16, 3/8, 1/2, 5/8, 3/4, 7/8, 1, 1 1/4, 1 1/2, 1 5/8, 1 3/4, 2, 2 1/2, 3 |
| 2.11 | 0.083 | 1/4, 3/8, 1/2, 5/8, 3/4, 7/8, 1, 1 1/4, 1 1/2, 1 5/8, 1 7/8, 2, 2 1/2, 3 |
| 2.41 | 0.095 | 1/2, 5/8, 1, 1 1/4, 1 1/2, 2 |
Seamless vs ERW Stainless Steel Tube: Which to Specify
| Point | Seamless round tube | ERW / welded round tube | Rectangular or square tube |
|---|---|---|---|
| Route | Pierced billet, cold drawn | Strip formed and welded, then annealed | Welded and shaped |
| Typical standards | A213, A269 SMLS, EN 10216-5 | A249, A269 WLD | A554 |
| Weld joint factor in design | None | Applies under pressure codes | Not for pressure service |
| Best fit | High pressure, high temperature, sour or critical lines | Moderate pressure, large volume, cost sensitive | Frames, handrails, architectural work |
For welded options, see the stainless steel welded tubes.
Where Seamless Stainless Steel Tubing Is Used: Industry Applications
| Sector | Typical seamless tube duty | Usual grades |
|---|---|---|
| Upstream oil and gas, offshore | Instrument and impulse lines, chemical injection, hydraulic control | 316L |
| Gas processing and LNG | Exchanger bundles, cryogenic instrument lines | 304L, 316L |
| Refining and petrochemicals | Shell and tube exchangers, heater and furnace tubing | 316L, 321, 347 |
| Power generation | Superheater and reheater tubes, feedwater heaters | 304H, 321H, 347H |
| Fertilizer | Urea and ammonia plant exchangers | 316L, 317L, 310S grades per licensor spec |
| Desalination and water | Exchanger and instrument tubing in low chloride sections | 316L; higher chloride duty moves to duplex |
| Chemical processing | Corrosive fluid transfer and heat recovery | 316L, 317L, 904L |
Related sector pages: oil and gas, refinery, petrochemical, chemical processing, marine and offshore.
Inspection and Testing of Stainless Steel Seamless Tubes
Every tube length ordered to ASTM A213 or A269 passes the checks set out in ASTM A1016 before it leaves the mill. Buyers can add further tests on the purchase order where the service calls for them.
Tests the standard requires
- Heat and product analysis to confirm the chemistry matches the ordered grade
- Tension, flattening, flaring and hardness tests on samples from each lot
- A hydrostatic test or an electric non-destructive test on every tube
- Dimensional checks on OD, wall and length against A1016 tolerances, plus visual inspection of the inside and outside surfaces
Tests buyers can add to the order
- Eddy current or ultrasonic examination for critical exchanger and instrument service
- Intergranular corrosion testing to ASTM A262 Practice E
- Positive material identification (PMI) on each tube or lot
Documentation: each lot is traceable to its heat number through the EN 10204 certificate.
Request a Quotation for Stainless Steel Seamless Tubes
Send your tube list with grade, standard, OD, wall, length and quantity, along with your certification and inspection requirements and the destination port. If your project carries an operator material specification, attach it so the quotation answers it line by line.
Request a QuotationStainless Steel Seamless Tube by Grade and Matching Products
Seamless tube by grade
- SS 304/304H/304L tube
- SS 316/316L/316Ti/316H tube
- SS 317/317L tube
- SS 321/321H tube
- SS 347/347H tube
- SS 310S/310H tube
- SS 904L tube
- Stainless steel welded tubes
- Bright annealed tubes
- Condenser tubes
SS Seamless Tube Frequently Asked Questions
Solution annealed austenitic grades such as 316L can be used within the environmental limits of ISO 15156-3, with hardness not above 22 HRC. Outside those limits, duplex or nickel alloys are normally specified. Send your operator's specification and we will confirm what can be certified.
ASTM A213 covers seamless tubes for boilers, superheaters and heat exchangers. ASTM A269 covers seamless and welded tubing for general corrosive service, so an A269 order should state seamless if seamless is required.
Minimum wall tube has all its tolerance on the plus side, so it is heavier and safer for pressure design. Average wall tube is lighter and cheaper. Check which one your datasheet calls for before requesting a price.
Cut lengths of 5.8 m and 11.8 m fit 20 ft and 40 ft containers. Random, fixed and U bend lengths are quoted to your drawing.
Grade, standard, OD, wall (MW or AW), length, quantity, end finish, condition, certification level, inspection agency, destination port and required date.
Metinox Overseas supplies stainless steel seamless tubes from approved Indian and international mills, with mill test certificates traceable to the producing mill. Tell us if your project requires a named mill or an approved manufacturer list.
Choose seamless where the design code applies a weld joint factor, where service is high pressure or above about 400°C, or where the client specification bans welded tube. Welded (A249, A269 WLD) is the lower-cost choice for moderate-pressure exchanger and process duty.
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