SS 321 / 347 Flanges
Teshi Group manufactures SS 321 / 347 flanges (ASTM A182 F321 / F321H / F347 / F347H, stabilised stainless) as an OEM in India — forged, machined, marked and certified in-house to ASME B16.5, ASME B16.47, EN 1092-1 and customer drawings.
Austenitic stainless steels are the everyday choice for corrosive process lines, with grades tuned for low carbon (L), molybdenum for chlorides (316, 317L), stabilisation for high temperature (321, 347) and oxidation resistance (310).
SS 321 / 347 flanges at a glance
| Material | SS 321 / 347 |
|---|---|
| Specification | ASTM A182 F321 / F321H / ASTM A182 F347 / F347H |
| UNS / W.Nr. | S32100 / S32109 / 1.4541 · S34700 / S34709 / 1.4550 |
| Sizes | NPS ½"–24" (ASME B16.5), 26"–60" (ASME B16.47 A / B), DN 10–600 (EN 1092-1) |
| Pressure class | Class 150, 300, 600, 900, 1500, 2500 · PN 6–40 |
| Facing / ends | RF, FF, RTJ, tongue & groove, male-female; serrated or smooth finish |
| Certification | EN 10204 3.1 standard · 3.2 with third-party inspection · IBR on request |
| Testing | PMI, hardness, dimensional; UT, IGC, impact and ferrite as specified |
SS 321 / 347 chemistry and mechanical properties
Chemical composition of SS 321 / 347 (weight %, maximum unless a range)
| Grade | C | Mn | Si | Cr | Ni | Nb | Ti |
|---|---|---|---|---|---|---|---|
| 321 / 321H | 0.08 | 2.00 | 1.00 | 17.0–19.0 | 9.0–12.0 | — | 5×(C+N) – 0.70 |
| 347 / 347H | 0.08 | 2.00 | 1.00 | 17.0–20.0 | 9.0–13.0 | 10×C – 1.10 | — |
Mechanical properties of SS 321 / 347 (minimum, room temperature)
| Grade | Tensile strength | Yield strength (0.2 %) | Elongation | Note |
|---|---|---|---|---|
| 321 / 321H | 515 MPa (75 ksi) | 205 MPa (30 ksi) | 30 % | Ti-stabilised |
| 347 / 347H | 515 MPa (75 ksi) | 205 MPa (30 ksi) | 30 % | Nb-stabilised |
Matching specifications by product form
| Grade | Forged flanges & fittings | Butt weld fittings | Plate | Pipe |
|---|---|---|---|---|
| 321 / 321HUNS S32100 / S32109 · W.Nr. 1.4541 | ASTM A182 F321 / F321H | ASTM A403 WP321 | ASTM A240 | ASTM A312 |
| 347 / 347HUNS S34700 / S34709 · W.Nr. 1.4550 | ASTM A182 F347 / F347H | ASTM A403 WP347 | ASTM A240 | ASTM A312 |
Limits and minimums from the governing ASTM / ASME specifications, summarised for convenience; the current edition takes precedence.
Pressure rating
Rated under the ASME B16.5 material group for stabilised stainless steels. The applicable rating table is issued with every quotation, and flanges are marked with class, material and heat number.
Types we manufacture
Dimension charts
Where SS 321 / 347 is used
- Chemical, fertiliser and pharmaceutical process piping
- Food, water and utility lines
- Refinery hydrotreater and high-temperature lines (321, 347)
- Furnace and kiln piping (310S)
- Cryogenic service
Testing & certification
- Solution annealed
- Intergranular corrosion test to ASTM A262 Practice E when specified
- PMI and dimensional inspection
- EN 10204 3.1 certificate
Related materials
FAQ
SS 321 / 347 flanges: common questions
What specification covers SS 321 / 347 flanges?
SS 321 / 347 flanges are forged to ASTM A182 F321 / F321H / ASTM A182 F347 / F347H and dimensioned to ASME B16.5, ASME B16.47 or EN 1092-1.
What is the chemical composition of 321 / 321H?
321 / 321H (UNS S32100 / S32109): C 0.08, Mn 2.00, Si 1.00, Cr 17.0–19.0, Ni 9.0–12.0, Ti 5×(C+N) – 0.70 (weight %; single values are maximums).
What are the minimum mechanical properties of 321 / 321H?
Tensile strength 515 MPa (75 ksi), yield strength 205 MPa (30 ksi), elongation 30 %.
Is Teshi Group a manufacturer of SS 321 / 347 flanges in India?
Yes. Teshi Group has manufactured flanges and fittings in India since 1971 and is ISO 9001:2015 certified and IBR approved. Every SS 321 / 347 piece is hard-stamped with its heat number and supplied with an EN 10204 3.1 certificate; 3.2 with third-party inspection on request.
What does the L in 304L and 316L mean?
L grades have carbon limited to 0.030 % to avoid chromium carbide precipitation during welding, which protects the weld zone from intergranular corrosion.
When should 321 or 347 be used instead of 304L?
321 (titanium-stabilised) and 347 (niobium-stabilised) resist sensitisation during long service at roughly 425–850 °C, so they are used in refinery hydrotreaters and high-temperature lines.
Ready to build to spec?
Share your drawing, bill of materials or technical requirements with the Teshi team.