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MLTI Private Limited (Moonlight Tube Industries) is based in Gujarat, India, where Stainless Steel 347 Pipe has been produced since 2008 with an annual capacity of nearly 8,000 MT. Grade TP347 is the niobium-stabilised member of the 18/10 chromium-nickel family. ASME SA-312 ties its niobium limit to carbon content instead of fixing a band: not less than ten times the carbon content, capped at 1.00%. Niobium, which is also known as columbium, claims carbon before chromium can reach it. Around that addition sit 17.0 to 19.0% chromium and 9.0 to 13.0% nickel, with carbon held to 0.08% maximum.
Certified minimums are 515 MPa tensile strength, 205 MPa yield strength and 35% elongation. We produce SS 347 pipe to ASTM A312 / ASME SA-312, dimensioned to ASME B36.19, from 1/8" NB to 10" NB in SCH 5S through SCH 80S, in single random lengths of 4.6 to 7.3 metres and double random lengths up to 12 metres. We supply this grade in both seamless and welded A312 routes. 347 Stainless Steel seamless pipe suits high-pressure service, while welded pipe offers a cost-effective option for larger sizes. Refinery transfer piping, superheater connections and exhaust ducting are typical duties for this grade. UNS S34700 can also be called 1.4550 in Europe. Each length passes the A999/A999M hydrostatic test before release against an EN 10204 3.1 certificate. We hold ISO 14001:2015 and ISO 45001:2018 certifications, with BIS, EIL, IBR and PED 2014/68/EU approvals.
Every ordering variable for ASTM A312 TP347 pipe belongs in one place, from the governing specification through to the end type. Full data sits in the specification table beneath.
| Parameter | Value |
|---|---|
| Applicable standard | ASTM A312: Seamless, Welded, and Heavily Cold Worked Austenitic Stainless Steel Pipes / ASME SA-312 |
| Dimensional standard | ASME B36.19 |
| Size range | 1/8" NB to 10" NB |
| Schedule | SCH 5S, SCH 10S, SCH 40S, SCH 80S to ASME B36.19; SCH 20S available as a mill schedule outside ASME B36.19 |
| Wall thickness | 1.24 mm to 12.70 mm, by NB and schedule |
| Length | Single random 4.6 to 7.3 m; double random up to 12 m; cut lengths to order |
| Manufacturing form | Seamless, welded (ERW) |
| Section profile | Round, square, rectangular |
| Finish | Mill finish; solution annealed and pickled |
| End type | Plain end; bevelled to order |
Alloy 347 is an 18/10 austenitic stainless steel whose defining addition is niobium, stated by SA-312 as a multiple of carbon rather than a flat range. The table below lists element limits for UNS S34700 pipe.
| Element | Composition (%) |
|---|---|
| Carbon (C) | 0.08 max |
| Manganese (Mn) | 2.00 max |
| Phosphorus (P) | 0.045 max |
| Sulphur (S) | 0.030 max |
| Silicon (Si) | 1.00 max |
| Chromium (Cr) | 17.0 to 19.0 |
| Nickel (Ni) | 9.0 to 13.0 |
| Niobium (Nb) | 10 x C min, 1.00 max |
| Iron (Fe) | Balance |
The mechanical properties of TP347 are fixed by four requirements, established by ASTM A370 methods on material in the solution-annealed condition. ASME SA-312 requirements follow in the table below.
| Property | Requirement |
|---|---|
| Tensile strength, min | 515 MPa (75 ksi) |
| Yield strength, min | 205 MPa (30 ksi) |
| Elongation in 50 mm, min, longitudinal | 35% |
| Elongation in 50 mm, min, transverse | 25% |
No wall-thickness reduction applies to TP347, so 515 MPa holds across every schedule. SA-312 sets neither a hardness nor a grain size limit.
SS 347 equivalent material designations vary by country, and an export drawing rarely arrives written to the ASTM one. The table below matches each register to this grade.
| Country or System | Designation |
|---|---|
| USA (UNS) | UNS S34700 |
| Europe (EN / W.Nr) | X6CrNiNb18-10 / 1.4550 |
| Japan (JIS) | SUS 347 / SUS347TP |
| India (IS) | X07Cr18Ni11Nb |
| China (GB) | 06Cr18Ni11Nb |
| France (AFNOR) | Z6CNNb18-10 |
| United Kingdom (BS) | 347S31 |
Two corrections matter because competing pages get them wrong: Stainless Steel UNS S34700 Pipe isn't S30347, and 1.4961 is another grade.
Route and section profile are separate choices on a 347 order, and both move the price. Two routes come first below: seamless and welded (ERW). Three profiles then close it out.
347 SMLS Pipe starts life as a solid billet, hot-pierced and drawn down to size, so the finished wall carries no joint along it. Boiler circuits and high-pressure refinery lines take this route, since there's no seam to radiograph.
347 Welded Pipe and 347 ERW Pipe are made from coil stock on welded routes. Forming rolls shape the pipe, the edges are joined, and the result is solution annealed. Above 4 inch NB, welded pipe is usually cheaper than seamless.
Round section carries the entire A312 range, and ASME B36.19 covers no other profile. Ordering data is normally nominal bore and schedule, though A312 also permits outside diameter and wall thickness.
Square
Square 347 pipe is made to order on our box section plant, from 12 x 12 mm to 100 x 100 mm, with walls from 1.0 mm to 6.0 mm, up to 12 metres long.
Rectangular
Rectangular section runs from 13 x 25 mm to 100 x 50 mm on the same wall range, again stopping at 12 metres. Frame and support work absorbs most of it.
Our rolling envelope for 347 stainless steel pipe runs 1/8" NB to 10" NB across five schedules. Outside diameters and nominal walls to ASME B36.19 fill the dimension chart below.
| Nominal Bore (mm) | Nominal Bore (INCH) | Outside Diameter (mm) | Sch-5S Thickness (mm) | Sch-10S Thickness (mm) | Sch-20S Thickness (mm) | Sch-40S Thickness (mm) | Sch-80S Thickness (mm) |
|---|---|---|---|---|---|---|---|
| 6 | 1/8 | 10.30 | 1.24 | 1.24 | 1.50 | 1.73 | 2.41 |
| 8 | 1/4 | 13.70 | 1.24 | 1.65 | 2.00 | 2.24 | 3.02 |
| 10 | 3/8 | 17.10 | 1.24 | 1.65 | 2.00 | 2.31 | 3.2 |
| 15 | 1/2 | 21.34 | 1.65 | 2.11 | 2.30 | 2.77 | 3.75 |
| 20 | 3/4 | 26.70 | 1.65 | 2.11 | 2.55 | 2.87 | 3.91 |
| 25 | 1 | 33.40 | 1.65 | 2.77 | 3.00 | 3.38 | 4.55 |
| 32 | 1 1/4 | 42.20 | 1.65 | 2.77 | 3.00 | 3.56 | 4.85 |
| 40 | 1 1/2 | 48.30 | 1.65 | 2.77 | 3.00 | 3.68 | 5.08 |
| 50 | 2 | 60.30 | 1.65 | 2.77 | 3.00 | 3.91 | 5.54 |
| 65 | 2 1/2 | 73 | 2.11 | 3.05 | 4.00 | 5.16 | 7.01 |
| 80 | 3 | 88.9 | 2.11 | 3.05 | 4.00 | 5.49 | 7.62 |
| 100 | 4 | 114.3 | 2.11 | 3.05 | 4.50 | 6.02 | 8.56 |
| 125 | 5 | 141.3 | 2.77 | 3.4 | 5.00 | 6.55 | 9.53 |
| 150 | 6 | 168.3 | 2.77 | 3.4 | 6.35 | 7.11 | 10.97 |
| 200 | 8 | 219.1 | 2.77 | 3.76 | 6.35 | 8.18 | 12.7 |
| 250 | 10 | 273.1 | 3.4 | 4.19 | 6.35 | 9.27 | 12.7 |
B36.19 defines no SCH 5S wall at 1/8" NB, so that size starts at SCH 10S. We despatch in single and double random lengths.
SS 347 pipe weight depends on nominal bore and schedule, supporting accurate material estimation, handling planning, and piping system weight calculations.
| Nominal Bore (mm) | Nominal Bore (INCH) | Sch-5S Weight (Kg/mt) | Sch-10S Weight (Kg/mt) | Sch-20S Weight (Kg/mt) | Sch-40S Weight (Kg/mt) | Sch-80S Weight (Kg/mt) |
|---|---|---|---|---|---|---|
| 6 | 1/8 | 0.276 | 0.28 | 0.33 | 0.37 | 0.47 |
| 8 | 1/4 | 0.39 | 0.49 | 0.58 | 0.631 | 0.8 |
| 10 | 3/8 | 0.49 | 0.63 | 0.74 | 0.845 | 1.1 |
| 15 | 1/2 | 0.8 | 1 | 1.08 | 1.27 | 1.62 |
| 20 | 3/4 | 1.03 | 1.28 | 1.52 | 1.68 | 2.2 |
| 25 | 1 | 1.3 | 2.09 | 1.94 | 2.5 | 3.24 |
| 32 | 1 1/4 | 1.65 | 2.7 | 2.90 | 3.38 | 4.47 |
| 40 | 1 1/2 | 1.91 | 3.11 | 3.35 | 4.05 | 5.41 |
| 50 | 2 | 2.4 | 3.93 | 4.24 | 5.44 | 7.48 |
| 65 | 2 1/2 | 3.69 | 5.26 | 6.81 | 8.63 | 11.4 |
| 80 | 3 | 4.51 | 6.45 | 8.37 | 11.3 | 15.2 |
| 100 | 4 | 5.84 | 8.36 | 12.18 | 16.07 | 22.3 |
| 125 | 5 | 9.47 | 11.57 | 16.81 | 21.8 | 31.97 |
| 150 | 6 | 11.32 | 13.84 | 25.36 | 28.3 | 42.7 |
| 200 | 8 | 14.79 | 19.96 | 33.31 | 42.6 | 64.6 |
| 250 | 10 | 22.63 | 27.78 | 41.77 | 60.5 | 96 |
Four sectors specify 347 pipes: refining, power generation, chemical processing and exhaust work. All four weld assemblies then sit inside the carbide precipitation range.
SS 347 Pipe serves reformer circuits, hydrocracker lines and hot product transfer inside a refinery. Field welds on that duty are rarely solution treated, so niobium stabilisation protects the heat affected zone.
Radiant superheater connections, reheater links and high-pressure steam pipes take this grade. Metal temperature there sits above the point where an unstabilised austenitic pipe would sensitise at every welded joint.
Chemical plants specify 347 pipe for hot process headers, cracked gas lines and jacketed runs passing repeatedly through the carbide range. Nitric acid duty is a different matter, since the grade holds up in oxidising media.
Heavy-duty exhaust manifolds, aircraft exhaust stacks and ring collectors are thin-section work under severe thermal cycling. Scaling resistance and weld integrity determine life.
SA-312 requires solution annealing at 1900°F (1040°C) minimum, followed by a water quench or equally rapid cooling. A stabilising treatment is available under supplementary requirement S6.
Post-weld annealing isn't usually specified, since niobium has already bound the carbon that would otherwise precipitate. ER347 is the matching filler classification. Intergranular corrosion testing to ASTM A262 Practice E can be added under S7.
TP347 is among the grades accepted by ASME B31.3 for service down to −425 °F [−250 °C] without qualification by impact tests. Cryogenic line work loses a testing step.
347 Stainless Steel Pipe ships in container and break-bulk consignments.
Stainless steel 347 pipe price can range from ₹200–₹552/kg in India and US$2.35–US$6.49/kg. Nickel and niobium each track their own index. Eight variables set the figure: nominal bore, wall, schedule, cut length, quantity, route, finish, and certification. A seamless length normally prices above an equivalent ERW one.
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.
Our range runs 1/8" NB to 10" NB to ASME B36.19, in single random and double random lengths, up to 12 metres.
Price per kilogram is ₹200–₹552/kg in India and US$2.35–US$6.49/kg. Prices may vary, since nickel and niobium move daily.
SS 347 pipe is UNS S34700, 1.4550 in Europe, SUS 347 in Japan and 347S31 in the UK.
Stabiliser choice is the whole difference: 347 SS uses niobium and 321 uses titanium.
316 pipe carries molybdenum and no stabiliser: it wins on chloride pitting, loses on welded hot service.
Five schedules are rolled: SCH 5S, 10S, 20S, 40S, and 80S, on walls of 1.24 mm to 12.70 mm.
Both forms are produced to ASTM A312 / ASME SA-312, and the welded output includes ERW.
Annealing after welding isn't normally required because niobium leaves no free carbon to precipitate.
Every consignment carries an EN 10204 3.1 mill certificate covering the heat analysis, tensile results, and hydrostatic test.
Cut lengths and non-standard quantities run through our own works.