Stainless Steel 304 Tube: SS 304, 304L and 304H Seamless & Welded Tubes
Metinox Overseas supplies and exports stainless steel 304 tube from Mumbai: seamless tube to ASTM A213 and welded tube to ASTM A249, in 304, 304L and 304H. On a drawing you may see the same material written as TP304 or SUS 304. The grades differ in carbon. Pick 304L if the tube will be welded and not annealed afterwards, and 304H if it will sit at high temperature for long periods. Most of our tubes go into heat exchangers, boilers and instrument lines, as straight lengths, U-bends or coils. If your drawing gives nominal bore and schedule instead of OD and wall, you need our stainless steel pipes.
Tube is ordered by actual outside diameter and wall thickness, not by nominal bore and schedule. If your drawing uses NPS and schedule, our SS 304 pipes page is the one you want. If it gives millimetres and a tolerance, you are in the right place.
Table of content
- Stainless Steel 304 Tube Specification
- Chemical Composition of SS 304, 304L and 304H Tube
- Mechanical Properties of 304, 304L and 304H Stainless Steel Tube
- Physical Properties of SS 304 Tube
- Equivalent Grades for SS 304/304H/304L Tube
- SS 304 Tube Sizes: OD, Wall Thickness and Weight Chart
- 304 vs 304L vs 304H Tube: Which Grade to Order
- Seamless vs Welded SS 304 Tubes
- Where a 304 SS Tube Works, and Where It Does Not
- Applications of Stainless Steel 304 Tube by Industry
- Testing, Inspection and Certification of SS 304 Tube
- Packing, Delivery and Export of 304 Stainless Steel Tube
- Stainless Steel 304 Tube FAQs
- Related Stainless Tubes and Pipes
Stainless Steel 304 Tube Specification
| Specification | Details |
| Standards | ASTM A213, A249, A269, A270 (sanitary), A554 (mechanical/ornamental) / ASME SA equivalents |
| Types | Seamless, ERW, Welded, Drawn |
| Forms | Straight, U-bend, Coil, Square and Rectangular (A554) |
| Seamless size range | 6.35 mm to 101.6 mm OD (1/4" to 4" OD) |
| Welded size range | 6.35 mm to 101.6 mm OD (1/4" to 4" OD) |
| Length | Single Random, Double Random, Cut Length |
| Ends | Plain end; square cut and deburred; bevelled on request |
| Finish | AP (annealed & pickled), BA (bright annealed), MP (mechanically polished), EP (electropolished) |
| Testing | Hydrostatic or Eddy-Current, Flattening and Flaring, IGC (A262), PMI on request |
Chemical Composition of SS 304, 304L and 304H Tube
| Grade | C | Mn | Si | P | S | Cr | Ni |
| 304 (TP304) | 0.08 max | 2.00 max | 1.00 max | 0.045 max | 0.030 max | 18.0 to 20.0 | 8.0 to 11.0 |
| 304L (TP304L) | 0.035 max | 2.00 max | 1.00 max | 0.045 max | 0.030 max | 18.0 to 20.0 | 8.0 to 12.0 |
| 304H (TP304H) | 0.04 to 0.10 | 2.00 max | 1.00 max | 0.045 max | 0.030 max | 18.0 to 20.0 | 8.0 to 11.0 |
Mechanical Properties of 304, 304L and 304H Stainless Steel Tube
| Grade | Tensile strength, min | Yield strength 0.2%, min | Elongation in 50 mm, min | Hardness, max |
| 304 (TP304) | 515 MPa (75 ksi) | 205 MPa (30 ksi) | 35 % | 90 HRB / 192 HBW |
| 304L (TP304L) | 485 MPa (70 ksi) | 170 MPa (25 ksi) | 35 % | 90 HRB / 192 HBW |
| 304H (TP304H) | 515 MPa (75 ksi) | 205 MPa (30 ksi) | 35 % | 90 HRB / 192 HBW |
Physical Properties of SS 304 Tube
| Property | Typical value |
| Density | 7.93 g/cm³ |
| Elastic modulus | 193 GPa |
| Mean thermal expansion, 0 to 100 °C | 17.2 µm/m·°C |
| Thermal conductivity at 100 °C | 16.2 W/m·K |
| Specific heat | 500 J/kg·K |
| Electrical resistivity | 0.72 µΩ·m |
| Magnetic response | Essentially non magnetic when annealed; light response possible after cold forming |
Equivalent Grades for SS 304/304H/304L Tube
| 304 | 304L | 304H | |
| ASTM type | TP304 | TP304L | TP304H |
| UNS | S30400 | S30403 | S30409 |
| EN number | 1.4301 | 1.4307 | 1.4948 |
| EN name | X5CrNi18-10 | X2CrNi18-9 | X6CrNi18-11 |
| JIS | SUS 304 | SUS 304L | SUS 304HTB |
SS 304 Tube Sizes: OD, Wall Thickness and Weight Chart
| OD mm | OD in | 0.89 mm (20 BWG) | 1.24 mm (18 BWG) | 1.65 mm (16 BWG) | 2.11 mm (14 BWG) | 2.77 mm (12 BWG) | 3.40 mm (10 BWG) | 4.19 mm (8 BWG) |
| 6.35 | 1/4 | 0.12 | 0.16 | |||||
| 9.53 | 3/8 | 0.19 | 0.26 | 0.32 | 0.39 | |||
| 12.70 | 1/2 | 0.26 | 0.35 | 0.45 | 0.56 | 0.69 | ||
| 15.88 | 5/8 | 0.33 | 0.45 | 0.58 | 0.72 | 0.90 | 1.06 | |
| 19.05 | 3/4 | 0.40 | 0.55 | 0.72 | 0.89 | 1.12 | 1.33 | 1.55 |
| 25.40 | 1 | 0.54 | 0.75 | 0.98 | 1.22 | 1.56 | 1.86 | 2.21 |
| 31.75 | 1 1/4 | 0.68 | 0.94 | 1.24 | 1.56 | 2.00 | 2.40 | 2.88 |
| 38.10 | 1 1/2 | 0.82 | 1.14 | 1.50 | 1.89 | 2.44 | 2.94 | 3.54 |
| 44.45 | 1 3/4 | 0.97 | 1.33 | 1.76 | 2.23 | 2.88 | 3.48 | 4.20 |
| 50.80 | 2 | 1.11 | 1.53 | 2.02 | 2.56 | 3.31 | 4.01 | 4.86 |
| 63.50 | 2 1/2 | 1.39 | 1.92 | 2.54 | 3.23 | 4.19 | 5.09 | 6.19 |
| 76.20 | 3 | 1.67 | 2.32 | 3.06 | 3.89 | 5.07 | 6.17 | 7.52 |
| 88.90 | 3 1/2 | 1.95 | 2.71 | 3.59 | 4.56 | 5.94 | 7.24 | 8.84 |
| 101.60 | 4 | 2.23 | 3.10 | 4.11 | 5.23 | 6.82 | 8.32 | 10.17 |
Note: Weights in kg per metre, calculated at 7.93 g/cm³.
Need a size that is not in the chart? Send OD, wall and length and we will confirm availability.
304 vs 304L vs 304H Tube: Which Grade to Order
Carbon is the real difference between the three versions, so choose by what happens to the tube after it leaves the mill.
| Version | UNS / EN | Carbon, % | Order it when |
| 304 (TP304) | S30400 / 1.4301 | 0.08 max | General exchanger, instrument, food and dairy service in fresh or treated water. |
| 304L (TP304L) | S30403 / 1.4307 | 0.035 max | The tube is welded into a tubesheet or system and will not be annealed afterwards. |
| 304H (TP304H) | S30409 / 1.4948 | 0.04 to 0.10 | Sustained service at high temperature, such as superheater and reheater tube. |
Note: Between roughly 425 and 850 °C, carbon can pull chromium out of the grain boundaries, a change called sensitisation. Low carbon 304L stays clear of it after welding, which is why a 304L SS tube is the usual pick for as welded bundles. 304H gives up that protection in exchange for strength under load at heat. A heat meeting both 304 and 304L can carry dual certification; ask when you enquire.
Seamless vs Welded SS 304 Tubes
| Seamless | Welded | |
| How it is made | Pierced hollow, then cold drawn to size | Strip formed, seam welded, then annealed and usually drawn |
| Standards | ASTM A213, A269 | ASTM A249, A269 |
| Choose for | Boilers, superheaters, high pressure, tight bundles | Instrumentation, sanitary lines, general exchangers, long single lengths |
| Cost and lead time | Higher | Usually lower |
Welded tube still carries a seam, but it is annealed and tested along the full length to the governing standard.
Where a 304 SS Tube Works, and Where It Does Not
304 tube earns its default status in most exchanger and instrument work. It also fails in predictable places, so here is the plain version.
- Works well in fresh and demineralised cooling water, steam and condensate, food, dairy and brewery lines, instrument air and gas, and low temperature duty.
- U bends carry residual stress from forming. Stress plus hot chlorides, above roughly 60 °C, is the recipe for stress corrosion cracking. Stress relieving helps. A change of grade helps more.
- Brackish water or seawater pits 304, sometimes within a season. It is the wrong tube for that water.
Where the water or process stream carries chlorides, describe the duty and we will price SS 316/316L tube alongside. For seawater condensers, where pitting resistance is the deciding factor, see super duplex UNS S32750 tube. The full comparison is in our guide to SS 304 versus SS 316.
Applications of Stainless Steel 304 Tube by Industry
| Sector | Typical use | Common form |
| Power and boilers | Condenser, feedwater heater and economiser tube in fresh water; superheater tube in 304H | Seamless straight and U bend |
| Sugar, distillery and brewery | Evaporator, heater and process tube | Welded and seamless straight |
| Food and dairy | Product and utility lines, clean in place circuits | A270 sanitary, polished bore |
| Chemical and fertiliser plants | Exchanger tube in mild, chloride free streams | Seamless and welded |
| Water treatment | Potable and treated water exchangers and lines | Welded straight |
| Pharmaceutical | Utility and purified water lines | Welded, bright annealed or polished |
| Instrumentation, refining and process plants | Impulse, sampling and instrument air tube | Coil and straight, A269 |
Testing, Inspection and Certification of SS 304 Tube
Every tube is tested to ASTM A1016 general requirements. The programme follows the governing product standard, and extra tests are added when you state them in the enquiry. The quality programme is set out on our Quality Policy page.
| Check | Detail |
| Pressure integrity | Hydrostatic or eddy current examination on each length |
| Formability | Flattening and flaring tests per the governing standard |
| Hardness and tensile | Per the governing standard, reported on the MTC |
| Intergranular corrosion | ASTM A262 on request |
| Material identification | PMI on request, useful where 304, 304L and 316 stock could be mixed |
| Mill test certificate | EN 10204 3.1 with every order |
| Witnessed certification | EN 10204 3.2 through BV, SGS or TUV, arranged at order stage on request |
Packing, Delivery and Export of 304 Stainless Steel Tube
- Tubes are end capped and bundled, with U bend sets crated per bundle and thin wall or polished tube packed in wooden crates.
- Grade, size and heat number are marked on the tube so traceability survives breaking down a bundle.
- Bundles do not rest on carbon steel, because iron contamination is where rust staining on new stainless starts.
- Lengths can be cut to 5.8 m for a 20 ft container; longer lengths are agreed at order.
- Lead time is confirmed at quotation.
On arrival, store the tube covered and off the ground, away from carbon steel and from salt laden air. The full routine is on our Packing and Dispatch page.
Stainless Steel 304 Tube FAQs
Seamless stainless tube is generally classified under HS 7304 41 (cold drawn) and welded stainless tube under HS 7306 40. Confirm the exact code with your customs broker for your product form.
Amount of carbon content in the metal. 304 permits a maximum carbon percentage of 0.08, whereas 304L and 304H allow for maximum carbon contents of 0.035 and 0.10, respectively. On account of lower level of carbon content in 304L, the metal is appropriate for welded tubes that are not subsequently annealed. On the contrary, the higher carbon content in 304H permits higher creep resistance at very high temperatures.
Seamless tube to ASTM A213 is usual for boilers, superheaters, high pressure and tight tube bundles. Welded tube to ASTM A249 or A269 is annealed and tested along its length, and suits instrumentation, sanitary lines and general exchangers, often at lower cost.
Choose 304H when the tube runs for long periods at high temperature under load, such as superheater and reheater duty, because its controlled carbon gives creep strength. For ordinary fresh water and process duty, 304 or 304L is enough. Check the temperature limit in your design code.
An EN 10204 3.1 mill test certificate is supplied with every order. EN 10204 3.2 certification witnessed by BV, SGS or TUV can be arranged on request. PMI and intergranular corrosion testing to ASTM A262 are also available on request.
Send the grade, standard, outside diameter, wall thickness, length, quantity, end finish, certification, inspection requirement, destination port and required date. Add your own material specification if the project has one.
Related Stainless Tubes and Pipes
- Stainless steel tubes: the full tube range and chloride ladder
- SS 316/316L tube: the step up for chlorides
- Super duplex UNS S32750 tube: seawater and desalination exchangers
- SS 310S tube: higher temperature oxidation duty
- SS 304 pipes: when your drawing uses NPS and schedule
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