Inconel Flanges
Giriraj Impex is a manufacturer, stockist, supplier and exporter of Inconel flanges in alloys 600 (UNS N06600), 625 (UNS N06625) and other Inconel grades on request. We manufacture Inconel flanges from forgings to ASTM B564 / ASME SB564, to ASME B16.5 from ½" to 24" NB in Class 150 to 2500, ASME B16.47 Series A and B and EN 1092-1, in weld neck, slip-on, blind, socket weld, threaded, lap joint and orifice types.
Inconel flanges join Inconel pipe, fittings and equipment in high-temperature, seawater, sour-gas and aggressive chemical service, so that the bolted joint has the same resistance to corrosion and heat as the rest of the system.
Specifications
| Item | Details |
|---|---|
| Material standard | ASTM B564 / ASME SB564 (nickel alloy forgings) |
| Alloys | Inconel 600 (N06600), Inconel 625 (N06625); 601 and 718 on request |
| Dimensional standards | ASME B16.5, B16.47 Series A and B, B16.36, B16.48, EN 1092-1 |
| Sizes | ½" to 24" NB (B16.5); 26" to 60" NB (B16.47) |
| Classes | 150, 300, 600, 900, 1500, 2500 |
| Facings | Raised face, flat face, ring type joint |
| Condition | Annealed (625) or as the alloy specification requires |
| Documents | Mill test certificate (MTC); third-party inspection on request |
Composition
Flanges have the composition of the alloy specified; ASTM B564 forgings in alloy 625 have strength comparable to annealed 625 pipe and plate.
| Alloy | Ni | Cr | Fe | Mo | Nb + Ta | C | Mn | Si | S | Other elements |
|---|---|---|---|---|---|---|---|---|---|---|
| 600 (N06600) | 72.0 min | 14.0–17.0 | 6.0–10.0 | – | – | 0.15 | 1.00 | 0.50 | 0.015 | Cu 0.50 |
| 625 (N06625) | 58.0 min | 20.0–23.0 | 5.0 | 8.0–10.0 | 3.15–4.15 | 0.10 | 0.50 | 0.50 | 0.015 | P 0.015, Al 0.40, Ti 0.40, Co 1.0 |
Nickel includes cobalt where stated in the standard. Footnotes as given in each ASTM specification.
Flange types
- Weld neck flanges – for high-pressure, high-temperature and cyclic service.
- Blind flanges – to close nozzles and line ends.
- Slip-on flanges and socket weld flanges where the specification allows.
- Lap joint flanges – an economical option: an Inconel stub end carries the fluid and a stainless or carbon steel backing flange carries the bolt load.
- Orifice, reducing and special flanges, and spectacle blinds.
Lap joint or solid Inconel?
Solid Inconel flanges give full corrosion resistance on every surface, including the bolt holes and outer edges, which matters in seawater, splash zones and external chemical exposure. Where only the wetted face needs the alloy and the outside environment is mild, a lap joint arrangement with an Inconel stub end and a less expensive backing flange can reduce cost, and also makes bolt-hole alignment easier during installation. For large or heavy-class flanges, carbon steel flanges with an alloy 625 weld overlay on the face and bore are another option. The choice is made in the piping specification.
Manufacturing and inspection
Inconel flanges are made from B564 forgings of the specified alloy, heat treated as required, and machined to the dimensional standard with the bore matched to the pipe schedule. Each flange is dimensionally inspected and marked with the manufacturer's identification, alloy and specification, size, class, bore schedule and heat number. Ultrasonic testing, liquid penetrant examination and third-party inspection can be added, and flanges can be supplied to NACE MR0175 / ISO 15156 on request.
Ordering
Please state the flange type, standard, size, class, facing, bore schedule, alloy and UNS number, quantity and any supplementary tests or inspection required.
Bolting and gaskets
Inconel flanges in seawater and sour service are often bolted with Inconel 625 or 718 studs and nuts, or with other corrosion-resistant bolting allowed by the project, to avoid galvanic or crevice attack on the bolting. Gaskets are chosen for temperature and chemical compatibility – spiral wound gaskets with Inconel windings are common in high-temperature service. See Inconel fasteners.
Pressure ratings for Inconel flanges
ASME B16.5 assigns nickel alloy forgings to material groups with their own pressure-temperature ratings. Alloy 625 has high strength and therefore high ratings for its class at moderate temperatures, while alloy 600 has lower strength but good high-temperature properties. Designers should use the B16.5 ratings for the specific material group and temperature rather than assume those of stainless or carbon steel flanges. For non-standard flanges, the rating comes from design calculations to the applicable code.
For high-temperature service, flange joints also need gaskets and bolting rated for the temperature, and allowance for relaxation of bolt load as the joint heats up.
Applications and related products
Inconel flanges are used in chemical and petrochemical plants, offshore and subsea oil and gas, flare systems, pollution control, power generation and heat-treatment equipment. They connect Inconel pipes and tubes and Inconel pipe fittings. Flanges and blinds can also be machined from Inconel plates and Inconel round bars where the specification allows; thin sections are supplied as Inconel wires. See all flange materials on the flanges page and alloy guidance on the Inconel page.
Frequently Asked Questions
ASTM B564 (ASME SB564) covers nickel alloy forgings, including Inconel 600 and 625 flanges. Dimensions follow ASME B16.5, B16.47 or EN 1092-1.
Inconel 625 is the usual choice for seawater and sour service because of its resistance to pitting and crevice corrosion and its high strength.
Yes. An Inconel stub end with a stainless or carbon steel backing flange is a lower-cost option where only the wetted surface needs the alloy and the external environment is mild.
Inconel 625 or 718 studs and nuts are common in seawater and sour service. Other corrosion-resistant bolting may be used where the project specification allows.
Yes. Inconel blind flanges are supplied to ASME B16.5 and B16.47 in all standard classes, as well as to drawings.
Yes. All Inconel flanges are supplied with mill test certificates, and third-party inspection can be arranged on request.
Request a Quote for Inconel Flanges
Tell us the product, grade, size, standard, quantity and delivery location, and our sales team will reply with a quotation.
Inconel® is a trademark of Special Metals Corporation.