SS347 Tube Sheet
Niobium-stabilized rather than titanium-stabilized — the practical choice over 321 whenever post-weld heat treatment isn't part of the fabrication plan, since niobium carbides hold up better through the as-welded condition.
Chemical Composition
| Element | Min % | Max % |
|---|---|---|
| Chromium (Cr) | 17.0 | 19.0 |
| Nickel (Ni) | 9.0 | 13.0 |
| Niobium + Tantalum (Nb+Ta) | 10×%C | 1.0 |
| Carbon (C) | — | 0.08 |
Mechanical Properties
| Property | Typical Value |
|---|---|
| Tensile Strength | 515 MPa min |
| Yield Strength (0.2% offset) | 205 MPa min |
| Elongation | 40% min |
| Max. Practical Service Temp. | ~870°C (oxidation-limited) |
Equivalent Grades
| Standard | Designation |
|---|---|
| ASTM / UNS | S34700 |
| EN / DIN | 1.4550 |
| JIS | SUS347 |
SA-965 / F347 Specification
When a drawing or RFQ cites SA-965 / F347 (or ASTM A965 Grade F347) with UNS S34700, it is pointing at an austenitic stainless-steel forging path — not a universal “tube sheet standard.” Confirm the ordered product form, grade designation and purchaser requirements against the drawing before procurement.
| Element | Reference |
|---|---|
| Specification | ASTM A965 / A965M |
| ASME designation | SA-965 / SA-965M where applicable (edition-dependent; confirm Code context) |
| Grade designation | F347 |
| UNS | S34700 |
| Product form | Austenitic stainless-steel forging |
| Application context | Pressure and high-temperature parts, subject to project requirements |
A965/SA-965 covers austenitic stainless-steel forgings for boilers, pressure vessels, high-temperature parts and associated equipment. F347 is the listed grade designation that corresponds to UNS S34700 (SS347). The finished tube-sheet geometry, machining, hole pattern and inspection scope remain purchaser / drawing requirements — they are not defined by naming A965 or SA-965 alone.
Do not treat A240, A182 and A965 as interchangeable. A practical procurement path when SS347 / F347 / S34700 appears on a drawing:
| Specification | Product form / role | How to read it for tube sheets |
|---|---|---|
| ASTM A240 / SA-240 | Plate, sheet and strip | Common plate path when the blank is machined from flat product |
| ASTM A182 / SA-182 | Forged / rolled piping components (F347 context) | Relevant when the callout is piping-component forging scope; confirm against the ordered part |
| ASTM A965 / SA-965 | Austenitic stainless-steel forgings (F347) | Investigate when the material is specified as a forging for pressure/high-temperature parts |
Continue from grade identity into product form and machining:
- Material specifications for tube sheets — ASTM/ASME education on the Standards hub
- Forged tube sheets by material specification — forging product-form path
- Specification-driven CNC tube sheet drilling — drawing-led machining / RFQ entry
- Grade designation and product-form reference — related designations across systems
- Tube sheet manufacturer in India — commercial manufacturer / enquiry path
347 vs. 321 — Which Stabilizer
See the full SS321 datasheet for the titanium-stabilized counterpart.
Available Product Forms
SS347 is most often specified as a U-Tube Tube Sheet for high-temperature process heater and boiler service where field welding without PWHT is common.
Applications
High-temperature process equipment fabricated or repaired in the field, where post-weld heat treatment is impractical — refinery furnace tubesheets, exhaust systems, and similar high-temperature welded assemblies.
Advantages & Limitations
Advantages
- Superior as-welded carbide stability vs. titanium stabilization
- Good high-temperature oxidation resistance
- No PWHT required for most applications
Limitations
- No molybdenum — same chloride limits as 304/321
- Cost premium over standard 304/316
- Less widely stocked than 321 in some markets
FAQ
Not universally "better" — if your fabrication process reliably includes post-weld heat treatment, 321 performs equivalently at typically lower cost. 347 earns its place specifically when PWHT isn't part of the plan.
No more than standard 304 or 321 — none of the stabilized grades add molybdenum, so chloride resistance is unchanged. For chloride service, 316/316L or duplex remains the correct choice regardless of stabilization needs.
Typically sourced to order given its specialist demand — send your specification and quantity for a confirmed schedule.