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SS 347H Seamless Tube
347H seamless tube carries no longitudinal weld, so nothing in the wall initiates a creep crack. ASTM A213 / ASME SA-213 covers it, drafted around boiler and superheater duty.
Stainless Steel 347H Tube Manufacturer in India
We at MLTI Private Limited (Moonlight Tube Industries) produce stainless steel 347H tube in Gujarat, India. We have an annual capacity of roughly 8,000 MT. Grade 347H is the niobium-stabilised, controlled-carbon form of Type 347, registered as UNS S34709 and ordered as TP347H. ASME SA-213 fixes carbon between 0.04 and 0.10%, chromium at 17.0 to 19.0%, and nickel at 9.0 to 13.0%. Welded tube ordered to SA-249 carries a tighter nickel ceiling of 12.0%. Niobium locks carbon into a stable carbide before chromium can form one at the boundary.
Certified minima in the solution-annealed condition are 515 MPa (75 ksi) tensile, 205 MPa yield and 35% elongation, with hardness capped at 90 HRB. Grain size is held at ASTM No. 7 or coarser, which carries creep-rupture strength past plain 347. Export enquiries reach us as SUS 347HTB and as austenitic stainless steel 347H tube. We manufacture 347H seamless tube to ASTM A213 / ASME SA-213 and 347H welded tube, ERW included, to ASTM A249 / ASME SA-249. Round section spans 12.7 mm to 101.6 mm outside diameter on gauges from 19 to 10, in lengths up to 24 metres, with square and rectangular profiles to order. Superheater elements, reheater banks and exchanger bundles absorb most of the grade. Our company is ISO 14001 and 45001 certified and holds BIS, EIL, IBR, PED 2014/68/EU and AD 2000-Merkblatt W0 approval.
Stainless Steel 347H Tube Specifications
Every ordering parameter for SS 347H tube sits in the table below, from governing specification through section, wall gauge, grain size and delivery condition.
| Parameter | Value |
|---|---|
| Applicable standards | ASTM A213 / ASME SA-213: Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-Exchanger Tubes ASTM A249 / ASME SA-249: Welded Austenitic Steel Boiler, Superheater, Heat-Exchanger, and Condenser Tubes |
| Manufacturing route | Seamless, welded (ERW) |
| Section | Round, square, rectangular |
| Outside diameter, round | 12.7 mm to 101.6 mm (1/2" to 4") |
| Wall thickness, round | 1.02 mm to 3.4 mm (19 SWG to 10 SWG) |
| Square section | 12 x 12 mm to 100 x 100 mm, wall 1.0 mm to 6.0 mm |
| Rectangular section | 13 x 25 mm to 100 x 50 mm, wall 1.0 mm to 6.0 mm |
| Length | To 24 metres round; to 12 metres box section; cut to order |
| Delivery condition | Solution annealed |
| Grain size | ASTM E112 No. 7 or coarser |
| Finish | Mill finish; pickled and passivated; polished to order |
SS 347H Tube Chemical Composition
Three entries separate 347H from its base grade under SA-213: a carbon window with a floor, a tightened chromium ceiling of 19.0 %, and a niobium multiplier of eight rather than ten. Heat-analysis limits for TP347H are shown in the table below.
| Element | Composition, % by mass |
|---|---|
| Carbon (C) | 0.04 – 0.10 |
| Manganese (Mn) | 2.00 max |
| Phosphorus (P) | 0.045 max |
| Sulphur (S) | 0.030 max |
| Silicon (Si) | 1.00 max |
| Chromium (Cr) | 17.0 – 19.0 |
| Nickel (Ni) | 9.0 – 13.0 (A213 / SA-213); 9.0 – 12.0 (A249 / SA-249) |
| Niobium (Nb / Cb) | 8 x C min, 1.10 max |
| Iron (Fe) | Balance |
Niobium, still called columbium across much of the trade, is the key element here. Tantalum rides in with it through commercial ferro-niobium, and the pair fix carbon as a niobium carbide. Chromium then stays in solution at the boundary, so a niobium stabilised stainless steel tube resists intergranular attack in the 425 to 815 °C sensitising band.
Stainless Steel 347H Tube Mechanical Properties
Wall thickness is sized from a certified yield floor, not a typical figure, so acceptance for TP 347H rests on the minima in the table that follows.
| Property | Value |
|---|---|
| Tensile strength, min | 515 MPa (75 ksi) |
| Yield strength, 0.2% offset, min | 205MPa (30 ksi) |
| Elongation in 50 mm, min | 35% |
| Hardness, max | 192 HBW / 200 HV / 90 HRB |
| Grain size, ASTM E112 | No. 7 or coarser |
Room-temperature strength matches grades 347 and 321H exactly, since SA-213 lists one set of minima across all three. Separation shows at temperature, where coarse grain buys creep-rupture life 347 can't reach.
Stainless Steel 347H Tube Equivalent Grades
The international designations equivalent to Stainless Steel 347H Tube are listed in the table below, along with the country and standards
| Country / Standard | Designation |
|---|---|
| USA (UNS) | UNS S34709 |
| Europe (EN) | EN 1.4912 |
| Japan (JIS) | SUS 347HTB |
| Russia (GOST) | 08Kh18N12B |
| China (GB/T) | 07Cr18Ni11Nb |
Stainless Steel 347H Tube Forms and Types
Two construction routes and three cross-sections cover what leaves our mill: seamless first, then welded (ERW), then the round, square and rectangular profiles.
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SS 347H Welded and ERW Tube
Welded tube starts as a slit strip, roll-formed and seam-welded without filler, then solution annealed to ASTM A249 / ASME SA-249. Electric resistance welding meets that no-filler condition, so 347H ERW tube is the lowest-cost route.
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SS 347H Round Tube
Eleven outside diameters, 12.7 mm through 101.6 mm, make up the round line, and it carries our highest volume. Exchanger bundles and instrument runs all take 347H stainless steel tubing in round form.
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SS 347H Square Tube
Our SS 347H square tube is a welded box section, 12 x 12 mm through 100 x 100 mm, with walls of 1.0 mm to 6.0 mm. Furnace framing uses most of it.
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SS 347H Rectangular Tube
Rectangular box section runs 13 x 25 mm to 100 x 50 mm on that same wall band, and fabricators need it where a member carries a bending load about one axis.
Stainless Steel 347H Tube Sizes
The SS 347H tube size chart covers common tube diameters with various BWG wall thicknesses and corresponding weights per metre.
TP347H Seamless Tube Size Chart
| Size | OD (mm) | 10 BWG (3.40 mm) Weight/MTR | 12 BWG (2.77 mm) Weight/MTR | 14 BWG (2.11 mm) Weight/MTR | 16 BWG (1.65 mm) Weight/MTR | 18 BWG (1.25 mm) Weight/MTR | 19 BWG (1.07 mm) Weight/MTR |
|---|---|---|---|---|---|---|---|
| 1/2" | 12.7 | 0.78 | 0.68 | 0.55 | 0.45 | 0.35 | 0.31 |
| 5/8" | 15.875 | 1.05 | 0.89 | 0.72 | 0.58 | 0.45 | 0.39 |
| 3/4" | 19.05 | 1.31 | 1.11 | 0.88 | 0.71 | 0.55 | 0.47 |
| 1" | 25.4 | 1.85 | 1.55 | 1.21 | 0.97 | 0.74 | 0.64 |
| 1 1/4" | 31.75 | 2.38 | 1.98 | 1.54 | 1.23 | 0.92 | 0.81 |
| 1 1/2" | 38.1 | 2.91 | 2.41 | 1.87 | 1.48 | 1.13 | 0.97 |
| 2" | 50.8 | 3.98 | 3.28 | 2.53 | 2.00 | 1.52 | 1.31 |
| 2 1/2" | 63.5 | 5.04 | 4.15 | 3.19 | 2.52 | 1.91 | 1.64 |
| 3" | 76.2 | 6.11 | 5.01 | 3.85 | 3.04 | 2.30 | 1.98 |
| 3 1/2" | 88.9 | 7.18 | 5.88 | 4.51 | 3.55 | 2.69 | 2.31 |
| 4" | 101.6 | 8.24 | 6.75 | 5.17 | 4.07 | 3.08 | 2.65 |
SS 347H ERW Tube Size Chart
| Size | OD (mm) | 10 SWG (3.25 mm) Weight/Mtr | 12 SWG (2.64 mm) Weight/Mtr | 14 SWG (2.03 mm) Weight/Mtr | 16 SWG (1.63 mm) Weight/Mtr | 18 SWG (1.22 mm) Weight/Mtr | 19 SWG (1.02 mm) Weight/Mtr |
|---|---|---|---|---|---|---|---|
| 1/2" | 12.7 | 0.75 | 0.65 | 0.55 | 0.45 | 0.34 | 0.29 |
| 5/8" | 15.875 | 1.01 | 0.86 | 0.72 | 0.58 | 0.44 | 0.37 |
| 3/4" | 19.05 | 1.26 | 1.06 | 0.88 | 0.71 | 0.53 | 0.45 |
| 1" | 25.4 | 1.76 | 1.47 | 1.21 | 0.97 | 0.72 | 0.61 |
| 1 1/4" | 31.75 | 2.27 | 1.88 | 1.54 | 1.23 | 0.91 | 0.76 |
| 1 1/2" | 38.1 | 2.77 | 2.29 | 1.88 | 1.49 | 1.10 | 0.92 |
| 2" | 50.8 | 3.78 | 3.11 | 2.54 | 2.01 | 1.48 | 1.24 |
| 2 1/2" | 63.5 | 4.79 | 3.93 | 3.20 | 2.53 | 1.85 | 1.55 |
| 3" | 76.2 | 5.79 | 4.75 | 3.86 | 3.05 | 2.23 | 1.87 |
| 3 1/2" | 88.9 | 6.80 | 5.57 | 4.52 | 3.57 | 2.61 | 2.18 |
| 4" | 101.6 | 7.81 | 6.39 | 5.18 | 4.09 | 2.99 | 2.50 |
Tolerance follows the ordering specification: A213 allows wall above the specified minimum and nothing under; A249 permits plus 18% and nothing under.
347H Tube Stainless Steel Industrial Applications
Four sectors specify most of the 347H stainless steel tube dispatched, and the equipment behind each follows.
Thermal Power Generation
Radiant and pendant superheater elements sit at the hottest metal temperature in a utility boiler, and coarse-grained TP347H holds creep strength there.
Petroleum Refining and Petrochemicals
Refinery circuits above 500 °C carry hot hydrocarbons through stabilised austenitic sections. A 347H heat exchanger tube holds out against polythionic acid cracking in shutdown conditions, and that failure mode decides grade on hydrotreater duty.
Heat Exchangers and Condensers
Shell-and-tube bundles and surface condensers take 347H condenser tube, where welding without post-weld annealing cuts retubing time. ASTM A249 names condenser service in its scope, so welded material qualifies directly.
Chemical Processing
Nitric acid concentrators, ammonia-plant waste-heat boilers and reformer convection banks pass hot process gas through 347H SS tubes. Thermal cycling would sensitise an unstabilised grade in that duty.
Welding and Machining SS 347H Tube
347H tube welds by all standard fusion and resistance processes without post-weld annealing, because niobium suppresses chromium-carbide precipitation in the heat-affected zone. Machining tracks 304, though the grade work-hardens fast: sharp tooling and steady feed beat spindle speed.
Heat Treatment and Testing of 347H Tube
For seamless tube to SA-213, solution treatment runs at 1100 °C minimum for cold-worked material and 1050 °C minimum for hot-rolled. Welded tube to SA-249 is solution treated at 1100 °C minimum. In each case the tube is water-quenched or rapidly cooled by other means. Annealing above 1065 °C can impair resistance to intergranular attack, so a lower-temperature stabilisation anneal follows where the order specifies one. Our laboratory covers PMI, tensile, hardness and dimensional inspection.
Stainless Steel 347H Tube Shipping and Packaging
The shipping and packaging process of ASTM A213 TP347H Tubes is given below.
- Round tube despatches to 24 metres and box section to 12 metres, cut to order.
- Bundles are strapped, end-capped, and stencilled with the heat number and specification, and every lot carries its own mill test certificate.
- Export cargo clears on FOB or CFR terms under Star Export House registration.
- Brazil, Vietnam and Turkey take regular consignments of SS 347H tube.
ASTM A213 TP 347H Tube Price
Stainless steel 347H tube price is approximately ₹385–₹1,500/kg and US$4.53–US$17.65/kg. The nickel and niobium input costs move week to week, so we'd rather quote the day's rate than publish a list that ages inside a month. Six variables set the figure: diameter, wall gauge, cut length, construction route, finish and order quantity.
Why Buy Stainless Steel 347H Tube From MLTI?
Buyers return to Moonlight Tubes for certified material, approved grades and stock that ships on schedule. Every order is backed by documented quality, a wide size range and delivery commitments we hold to.
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Stainless Steel 347H Tube: Frequently Asked Questions
SS 347H tube holds carbon at 0.04 to 0.10% against a 0.08% ceiling for SS 347, and its grain size must be ASTM No. 7 or coarser. Both changes lift creep-rupture strength.
Stainless Steel 347H tube is used for superheater, reheater, boiler, heat-exchanger and condenser service above 500 °C, plus refinery circuits exposed to shutdown sensitisation.
TP347H is a niobium-stabilised austenitic grade. Carbon runs 0.04 to 0.10%, chromium 17.0 to 19.0%, and niobium eight times the carbon content to 1.10% maximum, with manganese, phosphorus, sulphur and silicon held to standard limits. Nickel is 9.0 to 13.0% for seamless tube and 9.0 to 12.0% for welded.
347H SS tube performs better in dry high-temperature service; 316 performs better in chloride or dilute sulphuric media. Molybdenum explains the split.
No. 347H SS tube stays fully austenitic in the solution-annealed condition and reads non-magnetic under a pull test. Heavy cold work induces a faint response.
Both. Seamless 347H tube ships against ASTM A213 / ASME SA-213, welded and ERW 347H tube against ASTM A249 / ASME SA-249.
Yes. Niobium fixes carbon before chromium carbide forms in the heat-affected zone, so a stabilisation anneal is needed only where the design code calls for one.
Price is quoted at approximately ₹385–₹1,500/kg and US$4.53–US$17.65/kg. Then adjusted for diameter, wall gauge, length, route and quantity. Seamless costs more than ERW.