Stainless Steel Flanges
Giriraj Impex is a manufacturer, stockist, supplier and exporter of stainless steel flanges to ASTM A182 in grades F304, F304L, F316, F316L, F321, F347 and F310. We manufacture stainless steel flanges to ASME B16.5 from ½" to 24" NB in Class 150 to 2500, large-diameter flanges to ASME B16.47 Series A and B, and EN 1092-1 flanges, in weld neck, slip-on, blind, socket weld, threaded, lap joint and orifice types.
Stainless flanges are used to make bolted, removable joints in corrosive and hygienic piping systems, matching stainless steel pipes and fittings of the same grade.
Specifications
| Item | Details |
|---|---|
| Material standard | ASTM A182 / ASME SA182 (forged); ASTM A240 for plate flanges where specified |
| Grades | F304, F304L, F304H, F316, F316L, F316Ti, F321, F347, F310; dual certified F304/304L and F316/316L |
| Dimensional standards | ASME B16.5, B16.47 Series A and B, B16.36 (orifice), B16.48 (line blanks), EN 1092-1, MSS SP-44 |
| Sizes | ½" to 24" NB to ASME B16.5; 26" to 60" NB to ASME B16.47 |
| Pressure ratings | Class 150, 300, 400, 600, 900, 1500, 2500; PN 6 to PN 100 and above to EN 1092-1 |
| Facings | Raised face, flat face, ring type joint, tongue and groove |
| Documents | Mill test certificate (MTC); third-party inspection on request |
Flange types
- Weld neck flanges for high-pressure and high-temperature stainless lines.
- Slip-on flanges for lower-pressure utility and water lines.
- Blind flanges to close line ends and nozzles.
- Socket weld flanges for small-bore, high-pressure lines.
- Lap joint flanges with stainless stub ends – a cost-saving option where only the stub end contacts the fluid.
- Threaded, orifice and reducing flanges, and spectacle blinds.
Grades and properties
The most frequently ordered grades are F304/304L for general corrosion resistance and F316/316L for chloride and acid service; SS 316 flanges have their own page. The ASTM A182 requirements are shown below; the mill test certificate gives the actual values for each heat.
| Grade | UNS | C | Mn | P | S | Si | Cr | Ni | Mo |
|---|---|---|---|---|---|---|---|---|---|
| F304 | S30400 | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 18.0–20.0 | 8.0–11.0 | – |
| F316 | S31600 | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 16.0–18.0 | 10.0–14.0 | 2.00–3.00 |
Low-carbon grades F304L and F316L have a lower carbon limit; nitrogen and other elements as given in the standard.
| Grade | Tensile strength, MPa (ksi) | Yield strength, MPa (ksi) | Elongation in 50 mm, % | Reduction of area, % |
|---|---|---|---|---|
| F304 | 515 (75) | 205 (30) | 30 | 50 |
| F304L | 485 (70) | 170 (25) | 30 | 50 |
| F316 | 515 (75) | 205 (30) | 30 | 50 |
| F316L | 485 (70) | 170 (25) | 30 | 50 |
Values for solution-annealed forgings.
Manufacturing, testing and marking
Stainless flanges are forged from A182 material, solution annealed, then machined to the dimensional standard, with the bore matched to the pipe schedule and the facing finish to suit the gasket. Each flange is dimensionally inspected and marked with the manufacturer's identification, ASTM A182 grade, size, class, bore schedule and heat number. Optional tests include intergranular corrosion testing to ASTM A262 Practice E, ultrasonic examination and hardness testing. Faces are protected with covers and flanges are packed in wooden cases for transport. Flanges can be supplied to NACE MR0175 / ISO 15156 on request.
Applications
Stainless steel flanges are used in chemical and petrochemical plants, refineries, pharmaceutical and food processing, water treatment and desalination, pulp and paper mills, power plants and marine systems. They are matched with stainless steel seamless pipes, welded pipes, tubes and pipe fittings, and bolted with stainless steel fasteners such as B8M studs and 8M nuts. See all flange materials on the flanges page.
In hygienic plants, stainless flanges are often specified with smooth bores and polished faces so that no crevices are left at the joint.
Flanges can be supplied loose or as part of a full pipe, fitting and bolting package.
Choosing the flange grade
The flange grade normally follows the pipe: F304L with TP304L pipe, F316L with TP316L pipe, and so on, so that corrosion resistance and weldability are consistent across the joint. F321 and F347 are used with matching pipe in high-temperature service, and F304H where high-temperature strength is required. For cost-sensitive large lines, a lap joint arrangement uses a stainless stub end with a carbon steel backing flange, so that only the stub end is wetted.
Ordering stainless flanges
Please state the flange type, standard, size, class or PN, facing, bore schedule, grade, quantity and any supplementary tests or inspection required.
Other stainless steel forms
Flange blanks, special flanges and machined parts can also be made from stainless plates, circles, rings and round bars. We also supply stainless sheets, coils, wires, angles, channels and flats. For grade details see the stainless steel page.
Frequently Asked Questions
ASTM A182 (ASME SA182) covers forged or rolled stainless and alloy steel pipe flanges, forged fittings and valves for high-temperature service. Stainless grades include F304, F304L, F316, F316L, F321 and F347.
F316L has a lower maximum carbon content than F316, which reduces the risk of sensitisation during welding. Flanges are often dual certified F316/F316L, meeting the low carbon of 316L and the strength of 316.
ASTM A193 B8 or B8M studs with A194 Grade 8 or 8M nuts are common for stainless flanges. Where higher strength is needed, Class 2 (strain hardened) studs or B7 bolting may be specified.
Yes. Flanges above 24" NB are supplied to ASME B16.47 Series A or Series B, or to MSS SP-44 or customer drawings. Please state the series, as the two have different dimensions.
Yes. Intergranular corrosion testing to ASTM A262 Practice E can be added to the order, along with other supplementary tests and third-party inspection.
Raised face is standard for most stainless lines with spiral wound or PTFE gaskets. Flat face is used against non-metallic or lined equipment, and ring type joint for high-pressure service.
Request a Quote for Stainless Steel Flanges
Tell us the product, grade, size, standard, quantity and delivery location, and our sales team will reply with a quotation.