Monel Flanges
Giriraj Impex is a manufacturer, stockist, supplier and exporter of Monel flanges in Monel 400 (UNS N04400), with Monel K-500 on request. We manufacture Monel flanges from ASTM B564 / ASME SB564 forgings to ASME B16.5 from ½" to 24" NB in Class 150 to 2500, to ASME B16.47 for larger sizes, and to EN 1092-1, in weld neck, slip-on, blind, socket weld, threaded, lap joint and orifice types, with mill test certificates.
Monel flanges connect Monel pipe, fittings and equipment in seawater, HF alkylation, caustic and chemical service, where flanges in other materials would corrode or set up galvanic corrosion with the piping.
Specifications
| Item | Details |
|---|---|
| Material | ASTM B564 / ASME SB564 – Monel 400 (N04400); K-500 (N05500) to ASTM B865 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); larger to B16.47 |
| Classes | 150, 300, 600, 900, 1500, 2500; PN ratings to EN 1092-1 |
| Types | Weld neck, slip-on, blind, socket weld, threaded, lap joint, long weld neck, orifice, reducing, spectacle blind |
| Facings | RF, FF, RTJ |
| Condition | Annealed |
| Documents | Mill test certificate (MTC); third-party inspection on request |
Chemical composition and mechanical properties
| Alloy | Ni | Cu | Fe | Mn | C | Si | S | Al | Ti |
|---|---|---|---|---|---|---|---|---|---|
| 400 (N04400) | 63.0 min | 28.0–34.0 | 2.5 | 2.0 | 0.3 | 0.5 | 0.024 | – | – |
| K-500 (N05500) | 63.0 min | 27.0–33.0 | 2.0 | 1.5 | 0.25 | 0.5 | 0.01 | 2.30–3.15 | 0.35–0.85 |
Nickel includes cobalt. Limits as given in ASTM B127, B164 and B165 (alloy 400) and B865 (alloy K-500).
| Product | Tensile strength, MPa (ksi) | Yield strength 0.2%, MPa (ksi) | Elongation, % |
|---|---|---|---|
| Plate and sheet – ASTM B127 | 483 (70) | 193 (28) | 35 |
| Seamless pipe and tube – ASTM B165 | 483 (70) | 193 (28) | 35 |
| Rod and bar – ASTM B164 | 483 (70) | 172 (25) | 35 |
| Forgings – ASTM B564 | 483 (70) | 172 (25) | 35 |
Annealed condition. Hot-rolled, cold-worked and stress-relieved conditions have higher strength, with size limits as given in each standard.
Flanges are made from B564 forgings, whose properties are shown in the last row of the table. Background on the alloy is on the Monel page.
Pressure ratings
ASME B16.5 includes Monel 400 forgings in its nickel alloy material groups, with pressure-temperature ratings for each class. Because annealed Monel 400 has a lower yield strength than carbon steel, its ratings in a given class are lower than those of A105 flanges, especially at higher temperatures. The rating should always be taken from the B16.5 table for the actual material group and design temperature. Where a higher rating is needed, a higher class is selected.
Lap joint flanges with Monel stub ends
For large or low-pressure Monel piping, a common economical arrangement is a Monel stub end welded to the pipe, with a loose lap joint flange in carbon or stainless steel behind it. Only the stub end is wetted by the process fluid, so the more expensive Monel is used only where it is needed, and the loose flange rotates to make bolt-hole alignment easy. Solid Monel flanges are used where the whole flange may be exposed to the environment, such as seawater spray, or where the specification requires them.
How we manufacture Monel flanges
Monel flanges are machined from forged blanks or rings of certified Monel 400 that have been forged to shape and annealed. Machining covers the bore, facing, hub, flange thickness and bolt holes to ASME B16.5 or the specified standard, with a serrated or smooth face finish as ordered. Nickel alloys work-harden, so machining uses rigid set-ups and sharp tools. Every flange is marked with alloy, specification, size, class, facing and heat number and inspected for dimensions and finish before dispatch.
Bolting and gaskets
Monel flanges in seawater are often bolted with Monel K-500 studs, which are strong enough for most joints and avoid galvanic attack on the bolts. Alloy steel studs, if used, should be coated and kept dry. Gaskets must suit the service: PTFE-based gaskets for HF and chemical duty, and spiral-wound gaskets with Monel windings and suitable filler for higher pressures and temperatures. For RTJ flanges, ring gaskets in Monel or a softer material than the flange groove are used.
Ordering Monel flanges
Please give the alloy, flange type, size, class, facing and face finish, bore or pipe schedule for weld neck and socket weld flanges, quantity and any testing such as ultrasonic, dye penetrant or positive material identification, or third-party inspection. Flanges are packed in wooden boxes with faces protected.
Applications and related products
Monel flanges are used in seawater cooling and ballast systems, HF alkylation units, caustic soda and brine plants, crude overhead systems, chemical processing and marine engineering. Matching products include Monel pipes and tubes, Monel pipe fittings, Monel sheets and plates, Monel round bars and Monel fasteners. Flanges in other materials are on the flanges page.
Frequently Asked Questions
Monel 400 flanges are made from forgings to ASTM B564 (ASME SB564), with dimensions to ASME B16.5, B16.47 or EN 1092-1.
No. Annealed Monel 400 has a lower yield strength than A105, so its ASME B16.5 pressure ratings in each class are lower, particularly at higher temperatures.
Monel K-500 studs are often used in seawater service to match the flange material and avoid galvanic corrosion. Coated alloy steel studs are an alternative in dry conditions.
A Monel stub end is welded to the pipe and a loose carbon or stainless steel lap joint flange is fitted behind it, so only the wetted stub end is Monel.
Weld neck, slip-on, blind, socket weld, threaded, lap joint, long weld neck, orifice, reducing flanges and spectacle blinds.
Yes, on request. K-500 flanges are made from forgings to ASTM B865 where higher strength is required.
Request a Quote for Monel Flanges
Tell us the product, grade, size, standard, quantity and delivery location, and our sales team will reply with a quotation.
Monel® is a trademark of Special Metals Corporation.