Stainless Steel Flanges
Forged ASTM A182 stainless flanges from 1/2" to 60" in Class 150 to 2500 and PN 6 to PN 100 — weld neck, slip-on, blind, socket weld, lap joint and orifice in F304L, F316L, F321, F347, F51 and F53.
What is Stainless Steel Flange?
A stainless steel flange is a forged connecting component that bolts pipe, valves and equipment together with a gasketed joint, supplied to ASME B16.5 (1/2"–24"), ASME B16.47 Series A / B (26"–60") and EN 1092-1 (DN 10–DN 2000) in pressure classes 150, 300, 600, 900, 1500 and 2500 lb, or PN 6 to PN 100. Steelco supplies weld-neck, slip-on, blind, socket-weld, threaded, lap-joint, orifice, spectacle-blind and long weld-neck flanges forged to ASTM A182 in F304/304L, F316/316L, F321, F347, F44, F51 Duplex 2205 and F53 Super Duplex 2507.
All grades we stock in stainless steel flange.
Click any grade for its full chemical composition, mechanical properties, equivalents and typical applications. Every grade ships with EN 10204 3.1 / 3.2 certification from our Mumbai stockyard.
Why Choose Stainless Steel Flange
Forged, not cast or cut
ASTM A182 forgings have refined grain flow and no porosity, which is why pressure codes require forged flanges for hydrocarbon and steam service rather than plate-cut alternatives.
Complete flange type range
Weld-neck for high pressure and cyclic loading, slip-on for economy, blind for closures, socket-weld and threaded for small bore, lap-joint for frequent dismantling, orifice for metering.
Standard and custom facings
Raised face (RF) with 125–250 AARH serration, flat face (FF), ring-type joint (RTJ) with octagonal or oval grooves, tongue-and-groove and male-female facings.
Full class coverage
Class 150 through 2500 lb to ASME B16.5 / B16.47, and PN 6 to PN 100 to EN 1092-1, with dimensional inspection against the governing standard before dispatch.
Sour and seawater grades
F51 and F53 duplex flanges supplied to NACE MR0175 / ISO 15156 with ferrite count, impact testing and hardness records for subsea and sour-service duty.
Technical Specifications
| Attribute | Details |
|---|---|
| Standards | ASME B16.5 · B16.47 Series A / B · B16.36 (orifice) · B16.48 (spades) · EN 1092-1 · DIN 2573-2637 · JIS B2220 |
| Material Standard | ASTM A182 / ASME SA182 forged fittings and flanges |
| Size Range | 1/2" to 24" (B16.5) · 26" to 60" (B16.47) · DN 10 to DN 2000 (EN 1092-1) |
| Pressure Classes | 150 · 300 · 600 · 900 · 1500 · 2500 lb · PN 6 / 10 / 16 / 25 / 40 / 64 / 100 |
| Flange Types | Weld neck (WNRF), slip-on (SORF), blind (BLRF), socket weld (SWRF), threaded, lap joint, long weld neck, orifice, spectacle blind, ring spacer |
| Grades Stocked | F304 / F304L · F316 / F316L · F317L · F321 · F347 · F44 · F51 (2205) · F53 (2507) · F55 (Zeron 100) |
| Facings | RF (125–250 AARH), FF, RTJ (R & BX grooves), tongue & groove, male & female |
| Condition | Solution annealed and water quenched; hardness and ferrite tested for duplex grades |
| Testing | Ultrasonic per ASTM A388, dye penetrant, hardness, Charpy impact, IGC per ASTM A262, PMI, dimensional |
| Certification | EN 10204 3.1 / 3.2 · NACE MR0175 / ISO 15156 · PED 2014/68/EU · IBR on request |
Grade availability by pressure class
| Grade | UNS | 150 lb | 300 lb | 600 lb | 900 / 1500 lb | 2500 lb |
|---|---|---|---|---|---|---|
| F304 / F304L | S30400 / S30403 | |||||
| F316 / F316L | S31600 / S31603 | |||||
| F317L | S31703 | — | — | |||
| F321 | S32100 | — | ||||
| F347 | S34700 | — | — | |||
| F51 Duplex 2205 | S31803 | — | ||||
| F53 SDSS 2507 | S32750 | — |
Note: Sizes above 24" are supplied to ASME B16.47 Series A or B, or as plate-cut flanges where the code permits.
Use our free metal weight calculator — bars, sheets, plates, pipes and sections.
Grade chemistry and mechanical properties supplied in stainless steel flange.
Chemical composition and mechanical properties are grade properties, not form properties — the same grade keeps the same chemistry whether it is supplied as sheet, plate or coil. The tables below list the specified limits for each grade we stock in stainless steel flange, tested and certified to ASTM A182 / ASME SA182. Values are weight percent (maximum unless a range is shown); mechanical values are minima in the annealed condition.
Chemical composition (weight %)
| Grade | C | Mn | Si | P | S | Cr | Ni | N | Mo | Ti | Nb+Ta | Cu | Nb |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| SS 201UNS S20100 | 0.15 | 5.50–7.50 | 1.00 | 0.060 | 0.030 | 16.0–18.0 | 3.5–5.5 | 0.25 | — | — | — | — | — |
| SS 202UNS S20200 | 0.15 | 7.50–10.00 | 1.00 | 0.060 | 0.030 | 17.0–19.0 | 4.0–6.0 | 0.25 | — | — | — | — | — |
| SS 304 / 304LUNS S30400 / S30403 | 0.08 (304) / 0.030 (304L) | 2.00 | 0.75 | 0.045 | 0.030 | 18.0–20.0 | 8.0–10.5 | 0.10 | — | — | — | — | — |
| SS 316 / 316LUNS S31600 / S31603 | 0.08 (316) / 0.030 (316L) | 2.00 | 0.75 | 0.045 | 0.030 | 16.0–18.0 | 10.0–14.0 | 0.10 | 2.00–3.00 | — | — | — | — |
| SS 321 / 321HUNS S32100 / S32109 | 0.08 (321) / 0.04–0.10 (321H) | 2.00 | 0.75 | 0.045 | 0.030 | 17.0–19.0 | 9.0–12.0 | — | — | 5×C–0.70 | — | — | — |
| SS 310 / 310SUNS S31000 / S31008 | 0.25 (310) / 0.08 (310S) | 2.00 | 1.50 | 0.045 | 0.030 | 24.0–26.0 | 19.0–22.0 | — | — | — | — | — | — |
| SS 347 / 347HUNS S34700 / S34709 | 0.08 (347) / 0.04–0.10 (347H) | 2.00 | 0.75 | 0.045 | 0.030 | 17.0–19.0 | 9.0–13.0 | — | — | — | 10×C–1.00 | — | — |
| SS 317LUNS S31703 | 0.030 | 2.00 | 0.75 | 0.045 | 0.030 | 18.0–20.0 | 11.0–15.0 | — | 3.00–4.00 | — | — | — | — |
| SS 904LUNS N08904 | 0.020 | 2.00 | 1.00 | 0.045 | 0.035 | 19.0–23.0 | 23.0–28.0 | — | 4.00–5.00 | — | — | 1.00–2.00 | — |
| 17-4 PHUNS S17400 | 0.07 | 1.00 | 1.00 | 0.040 | 0.030 | 15.0–17.5 | 3.0–5.0 | — | — | — | 0.15–0.45 | 3.0–5.0 | — |
| SS 410 / 410SUNS S41000 / S41008 | 0.15 | 1.00 | 1.00 | 0.040 | 0.030 | 11.5–13.5 | 0.75 | — | — | — | — | — | — |
| SS 430UNS S43000 | 0.12 | 1.00 | 1.00 | 0.040 | 0.030 | 16.0–18.0 | 0.75 | — | — | — | — | — | — |
| SS 409 / 409MUNS S40900 / S40930 | 0.030 | 1.00 | 1.00 | 0.040 | 0.020 | 10.5–11.7 | 0.50 | — | — | 6×C–0.75 | — | — | — |
| SS 441UNS S44100 | 0.030 | 1.00 | 1.00 | 0.040 | 0.030 | 17.5–18.5 | 0.50 | — | — | 0.10–0.60 | — | — | 0.30–0.90 |
Balance iron. Single figures are maximum limits. Mill test certificates to EN 10204 3.1 are issued with every dispatch.
Mechanical properties (annealed, minimum)
| Grade | Tensile Strength (min) | Yield Strength (0.2%) | Elongation in 50 mm | Hardness (Rockwell B) | Tensile Strength (H900) | Yield Strength (H900) | Hardness (Rockwell C) | Tensile Strength (annealed) | Hardness (Rockwell B, annealed) |
|---|---|---|---|---|---|---|---|---|---|
| SS 201 | 515 MPa (75 ksi) | 275 MPa (40 ksi) | 40% min | 95 max | — | — | — | — | — |
| SS 202 | 515 MPa (75 ksi) | 275 MPa (40 ksi) | 40% min | 95 max | — | — | — | — | — |
| SS 304 / 304L | 515 MPa (75 ksi) | 205 MPa (30 ksi) | 40% min | 92 max | — | — | — | — | — |
| SS 316 / 316L | 515 MPa (75 ksi) | 205 MPa (30 ksi) | 40% min | 95 max | — | — | — | — | — |
| SS 321 / 321H | 515 MPa (75 ksi) | 205 MPa (30 ksi) | 40% min | 95 max | — | — | — | — | — |
| SS 310 / 310S | 515 MPa (75 ksi) | 205 MPa (30 ksi) | 40% min | 95 max | — | — | — | — | — |
| SS 347 / 347H | 515 MPa (75 ksi) | 205 MPa (30 ksi) | 40% min | 92 max | — | — | — | — | — |
| SS 317L | 515 MPa (75 ksi) | 205 MPa (30 ksi) | 40% min | 95 max | — | — | — | — | — |
| SS 904L | 490 MPa (71 ksi) | 215 MPa (31 ksi) | 35% min | 90 max | — | — | — | — | — |
| 17-4 PH | — | — | 10% min | — | 1310 MPa (190 ksi) | 1170 MPa (170 ksi) | 40–48 | — | — |
| SS 410 / 410S | — | 275 MPa (40 ksi) | 20% min | — | — | — | — | 480 MPa (70 ksi) | 96 max |
| SS 430 | 450 MPa (65 ksi) | 205 MPa (30 ksi) | 22% min | 89 max | — | — | — | — | — |
| SS 409 / 409M | 380 MPa (55 ksi) | 205 MPa (30 ksi) | 20% min | 88 max | — | — | — | — | — |
| SS 441 | 415 MPa (60 ksi) | 205 MPa (30 ksi) | 18% min | 89 max | — | — | — | — | — |
Typical annealed values; actual results are stated on the heat-specific mill test certificate.
Application Sectors
Oil & Gas
Wellhead, manifold and process flanges in F316L, F51 and F53 to NACE MR0175.
Refineries
High-temperature and high-pressure flanged joints in F321, F347 and F316H.
Chemical Plants
Corrosive-service flanged connections in F316L, F317L and F904L.
Power Generation
Steam and feedwater flanges in F304H and F321H, IBR certified.
Water & Desalination
Seawater and brine line flanges in F51 and F53 duplex.
Pharma & Food
Sanitary and utility flanges in polished F316L.
Shipbuilding & Marine
Deck and engine-room piping flanges in F316L to class approval.
Instrumentation
Orifice flanges, spectacle blinds and spacer rings for metering runs.
Cut, finished and certified to your drawing.
Material leaves our Mumbai facility finished to your specification — not as raw stock.
Why buy from Steelco.
Steelco Metal & Alloys is a Mumbai-based stockist, importer and exporter of stainless steel and nickel alloys, shipping certified material worldwide.
Quality & testing on every dispatch
- EN 10204 3.1 mill test certificate on every dispatch
- 3.2 certification with TÜV / SGS / BV / Lloyd's / IRS / IBR witness on request
- Positive Material Identification (PMI) with portable XRF / OES
- Dye-penetrant (DPT), ultrasonic (UT) and hydro testing on request
- NACE MR0175 / ISO 15156 compliance for sour service
- PED 2014/68/EU compliance for pressure equipment
- Heat-number stencilling and marking for full traceability
Deep ready stock
Flanges held from 1/2" to 24" in Class 150–2500 across F304L, F316L, F321, F347, F51 and F53 — standard classes dispatch in 24–72 hours, larger B16.47 sizes forged to order in 3–4 weeks.
Mill-direct sourcing
Approved supply from Jindal, JSL, Outokumpu, Aperam, Acerinox, Sandvik and leading Japanese and Korean mills — every item traceable to a named producer.
Full certification
EN 10204 3.1 mill test certificate as standard, 3.2 with TÜV, SGS, BV, Lloyd's, IRS or IBR witness, plus PMI, DPT and UT reports on request.
On-time worldwide delivery
Regular export shipments to the GCC, Africa, Southeast Asia, Europe, Latin America and the USA via Nhava Sheva (JNPT), Mundra and Mumbai ports.
How your material is packed and shipped.
Every consignment leaves our Mumbai facility protected for transit and documented for customs, whether it moves by road within India or by sea to an overseas port.
Domestic & export packing
- Flanges palletised face-to-face with plywood separators
- Sealing faces coated with rust preventive and covered with face protectors
- Steel banding and shrink wrap over each pallet
- Wooden cases for high-class and large-diameter flanges
Global shipments
- HS Code: 7307 21 00 (stainless steel flanges)
- FOB / CFR / CIF terms via Nhava Sheva (JNPT), Mundra and Mumbai ports
- Documentation: commercial invoice, packing list, MTC, bill of lading, COO, insurance
- Regular exports to the GCC, Africa, Southeast Asia, Europe, Latin America and the USA
Ready to price your requirement?
Share grade, size and quantity — our Mumbai desk responds with pricing, stock position and lead time, usually the same working day.
Frequently asked questions.
Answers to the questions our Mumbai desk is asked most often.
What is the difference between a weld-neck and a slip-on flange?
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A weld-neck flange has a tapered hub butt-welded to the pipe, transferring stress smoothly and performing best under high pressure, cyclic loading and temperature swings. A slip-on flange slides over the pipe and is fillet-welded inside and out; it is cheaper and easier to align, but carries a lower fatigue rating and is normally limited to lower-pressure classes.
How do I choose the pressure class?
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The class is selected from the design pressure and temperature using the pressure-temperature rating tables in ASME B16.5 for the specific material group. Ratings drop as temperature rises, so a Class 150 F316L flange rated 19 bar at ambient carries only about 10 bar at 300 °C. Send us the design conditions and we will confirm the class.
What does RF, FF and RTJ mean?
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They are flange facings. RF (raised face) is the most common, with a raised gasket seating area, usually serrated to 125–250 AARH. FF (flat face) mates full-face against cast-iron or GRP equipment. RTJ (ring-type joint) uses a machined groove and a metal ring gasket for high-pressure and high-temperature service, typically Class 600 and above.
Are your flanges forged or cut from plate?
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Our standard flanges are forged to ASTM A182, which pressure codes require for hydrocarbon and steam service because forging gives refined grain flow and no porosity. Plate-cut flanges are supplied only for low-pressure, non-code applications where the customer specifies them.
Can you supply duplex flanges to NACE MR0175?
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Yes. F51 Duplex 2205 and F53 Super Duplex 2507 flanges are supplied with NACE MR0175 / ISO 15156 certification, solution-annealing records, hardness capped at 32 HRC, ferrite count between 35 and 65%, and Charpy impact testing at −46 °C where the specification requires it.
What flange sizes above 24 inch can you supply?
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Sizes from 26" to 60" are supplied to ASME B16.47 Series A (MSS SP-44) or Series B (API 605), forged to order on a 3–4 week cycle, with dimensional inspection reports and ultrasonic testing to ASTM A388.