Stainless Steel, Duplex & Nickel Alloy Flanges
A flange is chosen by type, size, class and facing — and its pressure rating depends on the material group and temperature. Choose the family and grade, then the type. We supply forged flanges to ASME B16.5, B16.47 and EN 1092-1 with EN 10204 3.1 certificates.
- ASME B16.5
- ASME B16.47
- ASME B16.36
- ASME B16.48
- EN 1092-1
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is a pipe flange?
A flange is a forged ring or disc that bolts two pipe ends, a valve or a nozzle together with a gasket between the faces. Dimensions and pressure classes come from ASME B16.5 (NPS ½–24) or B16.47 (NPS 26–60); the material is a separate forging specification — ASTM A182 for stainless and duplex, B564 for nickel alloys, A105 or A350 for carbon steel.
How to order flanges: checklist
- Flange type — weld neck, slip-on, blind, socket weld, threaded, lap joint
- Size, pressure class and facing — e.g. 6" Class 300 RF
- Bore / schedule for weld neck flanges
- Material grade — e.g. ASTM A182 F316L or B564 N08825
- Dimensional standard — ASME B16.5, B16.47 Series A/B, EN 1092-1
- Certificate — EN 10204 3.1 or 3.2
Flanges by Material Family and Grade
Every flange page sits under its grade. Open it for the forging standard, B16.5 material group, facing and bolting.
Types of Flanges
Flange Pressure Ratings Explained
"Class 300" is not 300 psi. ASME B16.5 sorts forging materials into material groups and tabulates the allowable pressure for each class at each temperature; the rating falls as temperature rises. Two Class 300 flanges in different materials can have different ratings at the same temperature.
| Forging material | B16.5 group |
|---|---|
| A105 · A350 LF2 | 1.1 |
| A182 F11 Cl 2 | 1.9 |
| A182 F22 Cl 3 | 1.10 |
| A182 F304 | 2.1 |
| A182 F304L · F316L | 2.3 |
| A182 F321 | 2.4 |
| A182 F347 | 2.5 |
| A182 F51 · F53 · F55 (duplex) | 2.8 |
| B564 N04400 (Monel 400) | 3.4 |
| B564 N06600 (Alloy 600) | 3.5 |
| B564 N08825 · N06625 · B462 / B564 N10276 | 3.8 |
Read pressures from the B16.5 table for your group; your piping class governs.
Facing, Gasket & Bolting
| Facing | Gasket | Typical service |
|---|---|---|
| Raised face | Spiral-wound or sheet | Most service, Class 150–600 |
| Ring type joint | Metal ring, softer than the groove | High pressure / temperature |
| Flat face | Full-face gasket | Against cast-iron or non-metallic flanges |
Usual bolting: B7 studs with 2H nuts on carbon steel; B8 / B8M with 8 / 8M nuts on stainless; L7 with Gr 7L nuts for low temperature; project-specified alloy or coated bolting on duplex and nickel alloys. See fasteners.
Flanges Grades & Material Standards
| Grade | Material standard | Best for |
|---|---|---|
| Inconel 825 | ASTM B564 | Sulphuric and phosphoric acid service, chloride stress-corrosion cracking and sour gas |
| SS 904L | ASTM A182 F904L | Dilute sulphuric acid, phosphoric acid and chloride-bearing cooling water |
| SS 304 | ASTM A182 F304 | General corrosion resistance, food, water and architectural work |
| SS 304L | ASTM A182 F304L | Welded tanks, piping and vessels in general corrosive service |
| SS 310 / 310S | ASTM A182 F310 | Furnaces, burners and heat treatment at high temperature |
| SS 316 / 316L | ASTM A182 F316L | Chloride-bearing process fluids, marine air and pharmaceutical service |
| SS 321 | ASTM A182 F321 | High-temperature service between 425 and 815 °C |
| SS 347 | ASTM A182 F347 | Welded high-temperature piping in refineries and power plants |
| Duplex 2205 | ASTM A182 F51 / F60 | Strength with chloride resistance at a stainless-steel budget |
| Super Duplex 2507 | ASTM A182 F53 | Seawater and high-chloride service where strength also matters |
| Inconel 600 | ASTM B564 | High-temperature oxidation, caustic and nuclear service |
| Inconel 625 | ASTM B564 | Seawater, high strength and high temperature in one alloy |
| Inconel 718 | project / purchase specification dependent | Very high strength at temperatures up to about 650 °C |
| Incoloy 800 / 800H / 800HT | ASTM B564 | Furnaces, petrochemical heaters and high-temperature piping |
| Hastelloy C276 | ASTM B462 / B564 | The most aggressive mixed acids, wet chlorine and hypochlorite |
| Hastelloy C22 | ASTM B462 / B564 | Mixed oxidising and reducing acids, and weld overlays |
| Monel 400 | ASTM B564 | Seawater, hydrofluoric acid and marine service |
| Monel K500 | project / purchase specification dependent | High-strength pump shafts, bolting and springs in seawater |
| Super Duplex S32760 | ASTM A182 F55 | Seawater firewater, injection and offshore piping |
| ASTM A106 Gr B | ASTM A105 | High-temperature process and steam piping in refineries and power plants |
| ASTM A333 Gr 6 | ASTM A350 LF2 | Cold-climate and refrigerated piping down to −45 °C |
| ASTM A335 P11 | ASTM A182 F11 | Steam and hot-oil piping up to about 550 °C |
| ASTM A335 P22 | ASTM A182 F22 | High-pressure steam and hydrogen service up to about 580 °C |
Guides, tools & standards for flanges
Flanges for export
FOB / CIF · Nhava Sheva (JNPT), MumbaiFlanges — questions buyers ask
What does flange Class 300 mean?
It is a pressure class, not a pressure. The allowable pressure depends on the material group and temperature in ASME B16.5.
Which flange type should I use?
Weld neck for high pressure, temperature and cyclic loads; slip-on for low pressure and easy alignment; socket weld for small bore; blind to close a line; lap joint with stub end to save alloy.
What is the difference between B16.5 and B16.47?
B16.5 covers ½" to 24"; B16.47 covers 26" to 60" in Series A (heavier, MSS SP-44 pattern) and Series B (lighter, API 605 pattern), which do not interchange.
RF or RTJ?
Raised face with a spiral-wound gasket suits most service; RTJ with a metal ring is used for high pressure and temperature.