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Stainless steel grades
Request an SS 347H project quote with your standard, pipe schedule or tube wall, quantity and inspection requirements.
Request a quoteTechnical reference
| Field | Order reference |
|---|---|
| Standard | A312 TP347H pipe or A213 TP347H where specified |
| Product or route | High-temperature niobium-stabilised austenitic stainless, UNS S34709 |
| Critical dimensions and fit | Group lengths by boiler or hot-section equipment tag |
| Supply enquiry | Confirm sizes, lengths, route, documentation and lead time for your order |
Selected ASME B36.19 dimensions. Schedule columns give nominal wall thickness. Theoretical inside diameter and mass use nominal dimensions, with a reference density of 8,000 kg/m³. Actual mass varies by grade and tolerances.
| NPS | OD (mm) | 10S wall (mm) | 40S wall (mm) | 80S wall (mm) | 40S ID (mm) | 40S kg/m |
|---|---|---|---|---|---|---|
| 1 | 33.40 | 2.77 | 3.38 | 4.55 | 26.64 | 2.55 |
| 2 | 60.33 | 2.77 | 3.91 | 5.54 | 52.51 | 5.54 |
| 3 | 88.90 | 3.05 | 5.49 | 7.62 | 77.92 | 11.51 |
| 4 | 114.30 | 3.05 | 6.02 | 8.56 | 102.26 | 16.38 |
| 6 | 168.28 | 3.40 | 7.11 | 10.97 | 154.06 | 28.80 |
Reference ASME B36.19 dimensional standard · Tonkin stainless pipe dimensional chart
For tubing, order by actual outside diameter and wall. Drawing example: 38.1 × 3.2 mm tube by circuit and cut length.
Use the approved design code and service conditions. The applicable rating depends on material, temperature, minimum effective wall, joint details and the limits of the connected assembly. A schedule or a hydrostatic test result alone cannot establish an operating pressure.
Reference ASME process piping code B31.3
Selected chemistry by mass for the A312 pipe designations below. The ordered edition, full element limits and any applicable notes govern acceptance. A dash means the value is omitted here.
| Grade | UNS | C (%) | Cr (%) | Mo (%) | Grade feature |
|---|---|---|---|---|---|
| TP347H | S34709 | 0.04–0.10 | 17–19 | — | Niobium stabilised |
Reference ASTM A312/A312M scope · Centravis tubular product catalogue · Alleima high-temperature tubular grades
Selected minimum room-temperature tensile and yield strengths for A312 pipe. Elongation acceptance depends on the specimen orientation and applicable thickness basis. For tube orders, apply the nominated tube specification.
| Grade | Tensile minimum (MPa) | Yield minimum (MPa) |
|---|---|---|
| TP347H | 515 | 205 |
Reference ASTM A312/A312M scope · CTS A312 technical reference · Tioga A312 pipe grade reference
Check the heat-treatment and supplementary inspection scope before dispatch.
| When | What to check |
|---|---|
| Before ordering | Document the required test method, edition and any witness points |
| At delivery | Match the material report and heat or lot identification to the shipment |
A249 is a separate welded heat-transfer tube specification.
For the enquiry, group lengths by boiler or hot-section equipment tag.
A312 TP347H pipe or A213 TP347H where specified · 38.1 × 3.2 mm tube by circuit and cut length. Add quantity, lengths, delivery city and the required reports.
Ordering guidance
For 347H, quote the H grade, product form and order standard explicitly. Give either pipe NPS and schedule or actual tube OD and wall. A grade-only request leaves too much room for non-comparable offers.
For a project replacement, list any required supplementary testing and documentation alongside the dimension and quantity. Ask the quote to state exceptions before commercial approval.
Check pricing and availability →
Buyer’s guide
347H (UNS S34709) is the high-temperature variant of the niobium-stabilised 347 family. Record the exact grade for each equipment tag. If a maintenance order combines 347H hot sections with 347 or other material elsewhere, list them separately so receiving and fabrication teams can identify each line.
For boiler or exchanger tubing, check whether the drawing specifies a seamless or welded product standard and whether the ordered wall is minimum or nominal. For a pipe order, use the specified pipe standard and dimensional basis instead. A common chemistry family does not make these manufacturing routes and tolerances interchangeable.
Supply any mandatory reports or checks required by the order, including the delivery condition and traceability. Ask the supplier to indicate exceptions or additional inspection lead time in the offer. Where the order is cut into individual lengths, agree markings or bundle labels so the certificate can be traced back after cutting.
An outage list can identify each 347H tube by equipment tag, product standard, OD, wall basis and finished length. Add the number of pieces and any documented inspection hold point alongside the required arrival date.
Keep the designations distinguishable unless the plant’s approved material control system expressly addresses the intended use and traceability.
Technical references Alleima high-temperature tube grades · ASTM steel standards directory
Prepare your enquiry
| Item | What to send |
|---|---|
| Product details | 347H · nominated standard · size basis · wall · quantity · tests |
| Delivery | Quantity with units, delivery city and required date if known |
| Acceptance | Required certificates and inspection scope; attach the drawing revision where applicable |
UNS S34709 — 347H is a separate material designation from 347 (S34700).
They are different line items unless the project authority approves a substitution. Compare the exact grade and certificate evidence.
Technical reference: Grade designation reference
Project enquiries
Send your dimensions, quantities and delivery city. Include any inspection or material certificate requirements so they can be quoted against the same line items.
Request a quote → Call +91 99204 92715