Stainless Steel 347 / 347H Tubes are a niobium stabilised austenitic stainless steel tubing supplied by Metinox Overseas. They are available in seamless and weld form in accordance with ASTM A213, A269 and A312 as boiler, superheater, heat exchanger and process tubes. Niobium is used as a stabiliser and forms niobium carbide with carbon, helping to retain chromium at the grain boundaries when the tubes are exposed to temperatures between approx 425-815°C. This prevents sensitisation and cracking in moist acidic environments that unstabilised 304 may suffer from. 347H is chosen in the GCC and other export markets when creep strength determines the wall thickness. Browse the full range on our stainless steel tubes page.
Table of Contents
- ASTM A213 TP 347 Stainless Steel Seamless Tubes Specification
- SS 347/347H Tubes Chemical Composition
- Stainless Steel 347/347H Tubes Mechanical & Physical Properties
- Stainless Steel 347/347H Tubes Equivalent Grades
- SS 347 Pipes & Tubes Size Chart
- SS 347 ERW Tubes, SS EFW 347 Tubes and Stainless Steel 347 Capillary Tubes
- Stainless Steel 347/347H Tube Application
- What Affects the Price of Stainless Steel 347 & 347H Tubes
- Request a Quote for Stainless Steel 347 & 347H Tubes
- Complete the System: SS 347 Fittings and Flanges
- Stainless Steel 347 Pipes & Tubes: Buyer Questions
ASTM A213 TP 347 Stainless Steel Seamless Tubes Specification
| Item | Detail |
|---|---|
| Standards | ASTM A213 / ASME SA213 (seamless), ASTM A249 / ASME SA249 (welded), ASTM A269 (seamless and welded, general service |
| Dimensional tolerances | ASTM A1016 (A213, A249); ASTM A1016 / A269 Table for A269 tube |
| Welded Tube Size | 3.2 mm to 127 mm OD |
| Seamless Tube Size | 3.2 mm to 127 mm OD (1/8" to 5" OD) |
| Thickness | 0.4 mm to 12.7 mm, specified as minimum or average wall |
| Length | Single Random, Double Random & Required Length |
| Forms | Round, U bend, coiled, capillary (square and rectangular to A554, non-pressure only) |
| Types | Seamless (cold drawn, hot finished), welded, ERW, EFW |
| Ends | Plain, bevelled, threaded |
| Finish | Annealed and pickled, bright annealed, polished |
Note: A213 TP347H requires solution treatment at a minimum temperature and a grain size requirement for H grades.
SS 347/347H Tubes Chemical Composition
Weight %, maximum unless a range is shown. Values per ASTM A213 / A312.
| Element | TP347 (S34700) | TP347H (S34709) |
|---|---|---|
| C | 0.08 | 0.04 to 0.10 |
| Mn | 2.00 | 2.00 |
| P | 0.045 | 0.045 |
| S | 0.030 | 0.030 |
| Si | 1.00 | 1.00 |
| Cr | 17.0 to 19.0 | 17.0 to 19.0 |
| Ni | 9.0 to 13.0 | 9.0 to 13.0 |
| Nb | 10 × C min, 1.10 max | 8 × C min, 1.10 max |
Stainless Steel 347/347H Tubes Mechanical & Physical Properties
| Property | Metric | Imperial |
|---|---|---|
| Tensile strength, min | 515 MPa | 75 ksi |
| Yield strength (0.2 % offset), min | 205 MPa | 30 ksi |
| Elongation in 50 mm, min | 35 % | 35 % |
| Hardness, max (A213 tube) | 192 HBW / 90 HRB | 192 HBW / 90 HRB |
| Density | 8.0 g/cm³ | 0.289 lb/in³ |
| Melting range | 1400 to 1425 °C | 2550 to 2600 °F |
| Modulus of elasticity | 193 GPa | 28 × 10⁶ psi |
| Mean thermal expansion, 20 to 100 °C | 16.6 µm/m·°C | 9.2 µin/in·°F |
| Thermal conductivity at 100 °C | 16.2 W/m·K | 9.4 BTU/h·ft·°F |
| Electrical resistivity | 0.73 µΩ·m | 28.7 µΩ·in |
Stainless Steel 347/347H Tubes Equivalent Grades
| Grade | UNS | EN / Werkstoff Nr | EN name | JIS | BS (old) |
|---|---|---|---|---|---|
| 347 | S34700 | 1.4550 | X6CrNiNb18 10 | SUS 347 | 347S31 |
| 347H | S34709 | 1.4961 | X8CrNiNb16 13 | SUS 347H | 347S51 |
SS 347 Pipes & Tubes Size Chart
| OD (mm) | OD (in) | Common wall range (mm) | Common wall range (in) |
|---|---|---|---|
| 6.35 | 1/4 | 0.89 to 1.65 | 0.035 to 0.065 |
| 9.53 | 3/8 | 0.89 to 1.65 | 0.035 to 0.065 |
| 12.70 | 1/2 | 0.89 to 2.11 | 0.035 to 0.083 |
| 19.05 | 3/4 | 1.24 to 2.77 | 0.049 to 0.109 |
| 25.40 | 1 | 1.65 to 3.40 | 0.065 to 0.134 |
| 38.10 | 1 1/2 | 1.65 to 3.40 | 0.065 to 0.134 |
| 50.80 | 2 | 1.65 to 4.19 | 0.065 to 0.165 |
Pipe sizes to ASME B36.19M (ASTM A312 TP 347 pipes).
| NPS | DN | OD (mm) | OD (in) | Sch 10S (mm) | Sch 40S (mm) | Sch 80S (mm) |
|---|---|---|---|---|---|---|
| 1/2 | 15 | 21.3 | 0.840 | 2.11 | 2.77 | 3.73 |
| 3/4 | 20 | 26.7 | 1.050 | 2.11 | 2.87 | 3.91 |
| 1 | 25 | 33.4 | 1.315 | 2.77 | 3.38 | 4.55 |
| 2 | 50 | 60.3 | 2.375 | 2.77 | 3.91 | 5.54 |
| 4 | 100 | 114.3 | 4.500 | 3.05 | 6.02 | 8.56 |
| 6 | 150 | 168.3 | 6.625 | 3.40 | 7.11 | 10.97 |
| 8 | 200 | 219.1 | 8.625 | 3.76 | 8.18 | 12.70 |
For more pipe dimensions and pressure ratings, see SS 347 / 347H pipe.
Sizes outside these ranges can be made to order: send your size, schedule or class and quantity. Request a quote for 347 / 347H tubes
SS 347 ERW Tubes, SS EFW 347 Tubes and Stainless Steel 347 Capillary Tubes
Stainless steel 347 tubing comes in several forms, and the right one depends on pressure, diameter and service. The table below shows the standard each form is made to and where it is normally used.
| Form | Standard | Typical use |
|---|---|---|
| Seamless tube | ASTM A213, A269 | Superheaters, reheaters, high pressure exchangers |
| Welded tube | ASTM A249, A269 | Feedwater heaters, general heat exchangers |
| ERW tube | ASTM A249, A269 | Exchanger and condenser bundles, utility lines |
| EFW pipe | ASTM A358 | Large diameter, high temperature transfer lines |
| Capillary tube | ASTM A269, A213 | Instrument, sampling and impulse lines |
| Rectangular / square tube | ASTM A554 | Structural and ornamental parts, not pressure service |
For pipe forms in this grade, see 347/347H seamless pipes, 347/347H welded pipes and ASTM A358 TP 347 Stainless Steel EFW Pipes. The seamless vs welded stainless steel pipe guide explains the trade off.
Stainless Steel 347/347H Tube Application
| Sector | Where 347 / 347H tubes are used |
|---|---|
| Refining | Fired heater and reformer tubes, hydrotreater and hydrocracker effluent exchangers, where polythionic acid stress corrosion cracking during shutdown is a known risk |
| Petrochemicals | Ethylene and aromatics plant exchangers, high temperature transfer lines |
| Power | Superheater and reheater tubing in boilers and HRSGs |
| Gas processing and LNG | High temperature regeneration and heater circuits |
| Fertilizer | Ammonia plant waste heat and process exchangers |
| Instrumentation | Capillary and small bore tubing for sampling and impulse lines |
Related reading: Refinery pipes and tubes, Petrochemical pipes and tubes, Oil and gas pipes and tubes.
What Affects the Price of Stainless Steel 347 & 347H Tubes
Prices move with nickel and niobium markets, so every quote is made to order. Price depends on:
- Grade and heat: 347 against 347H, or dual certified heats
- Size, wall and form: seamless costs more than welded, and capillary and U bend add processing
- Quantity and length
- Stock against mill order
- Certification level: EN 10204 3.1 or 3.2
- Third party inspection and extra testing (hydrostatic, eddy current, IGC, grain size)
- Sour service hardness testing
- Incoterm and destination port
For a fast quotation, send: grade, standard, OD, wall (minimum or average), length, quantity, end finish, certification, inspection, destination port and required date.
Request a Quote for Stainless Steel 347 & 347H Tubes
Send your tube schedule or material requisition with the details listed above, plus any end user specification that applies. We will check it against the governing ASTM standard and reply with a priced offer.
Request a QuotationComplete the System: SS 347 Fittings and Flanges
- SS 347 pipe fittings (ASTM A403 WP347 butt weld, ASTM A182 F347 forged)
- SS 347 flanges (ASTM A182 F347)
- SS 347H flanges (ASTM A182 F347H)
Sister stabilised grade: Stainless steel 321 / 321H tubes. Other high carbon grades: 304H tubes and 316H tubes. Compare all grades in the stainless steel pipe grades chart.
Stainless Steel 347 Pipes & Tubes: Buyer Questions
347H holds carbon between 0.04 and 0.10 %, while 347 allows up to 0.08 % with no minimum. The controlled higher carbon gives 347H better creep strength above about 540 °C, which is why boiler and heater codes call for it.
Both are stabilised grades. 347 uses niobium, and 321 uses titanium. Niobium carbides are more stable, and niobium carries across a welding arc better than titanium, so 347 is often preferred for welded assemblies and for the hottest service.
Yes, within the limits of ISO 15156 Part 3: solution annealed, 22 HRC maximum, and inside the chloride, temperature and H₂S limits set for austenitic stainless steels. For hot, high chloride sour service, specify a higher alloy.
Lengths of 5.8 m and 11.8 m fit 20 ft and 40 ft containers. Other cut lengths, U bends and coils are made to drawing.
Grade, standard, OD, wall (minimum or average), length, quantity, end finish, certification, inspection, destination port and required date.
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