What copper nickel flanges are
Copper nickel flanges, also written Cu-Ni or CuNi flanges, are pipe flanges made from copper-nickel alloys. They are chosen for seawater and other chloride-bearing water, where carbon steel corrodes quickly and where a metallic, weldable, fabricable alloy is needed.
For US industrial buyers, the practical points are the alloy, the flange type, the dimensional standard and the documentation. This page links each of them.
The two alloys
| Alloy | UNS (wrought) | Where it fits |
|---|---|---|
| <a href="/materials/copper-nickel-90-10/">Copper Nickel 90/10</a> | C70600 | General seawater piping, cooling water, firewater, ballast |
| <a href="/materials/copper-nickel-70-30/">Copper Nickel 70/30</a> | C71500 | Demanding duty, higher velocity, desalination, heat exchangers |
Chemistry and mechanical properties are set by the applicable ASTM or ASME material specification. Our alloy comparison helps you choose.
Flange types we manufacture
- Copper nickel weld neck flange: Tapered hub, butt-welded to the pipe, for demanding seawater and high-integrity service.
- Copper nickel slip-on flange: Slides over the pipe and is fillet welded; quick to fit for lower-demand seawater lines.
- Copper nickel blind flange: Solid closure for pipe ends, nozzles and headers, with a machined sealing face.
- Copper nickel socket weld flange: Pipe seats in a counterbore and is fillet welded; used on small-bore lines.
- Copper nickel threaded flange: Internally threaded for joints made without welding.
- Copper nickel lap joint flange: Loose backing flange used with a stub end; easy bolt-hole alignment.
- Copper nickel composite flange: Copper nickel wetted component combined with a backing flange, built to your drawing.
- Copper nickel orifice flange: Paired flanges with pressure taps for orifice-plate flow measurement.
- Copper nickel spectacle blind flange: Figure-8 isolation device: one solid disc, one open ring, rotated to open or close the line.
- Copper nickel rtj flange: Ring-groove facing for metal ring gaskets in higher-pressure joints.
- Copper nickel expander flange: Combines a flange with a bore step-up, replacing a separate reducer and flange.
- Copper nickel custom manufacturing flange: Non-standard copper nickel flanges made to your drawing.
Standards: keep four things separate
- Dimensional standard: for example ASME B16.5 (NPS 1/2 to 24) or ASME B16.47 (larger sizes)
- Material standard: for example ASTM B151 bar or ASTM B122 plate for the alloy
- Testing and inspection: from your purchase order or project specification
- Project requirements: drawings, marking, documentation and class-society additions
Manufactured to applicable ASME/ASTM requirements based on project specification. Pressure class availability depends on flange type, size, material and standard, and the rating basis for copper nickel comes from your governing code. See NPS and pressure classes.
Supplying USA buyers from India
Sunflex Metalloy Pvt. Ltd. was established in 2010 and operates three manufacturing units in Gujarat, India. We provide technical information in USA terminology (NPS, ASME, ASTM) and can arrange documentation according to project requirements. Certifications and documentation are available upon request; see certifications.
What to include in an enquiry
- Alloy and material specification
- Flange type, NPS, class and facing
- Quantity and delivery date
- Drawings or specifications
- Documents needed: MTC, dimensional report, certificate of conformity, PMI, third-party inspection
Copper nickel flange FAQs
What are copper nickel flanges used for?
They join copper-nickel piping in seawater, cooling-water, firewater, ballast and other chloride-bearing water systems on ships, offshore facilities, desalination plants and coastal industrial sites.
Which copper nickel alloys do you supply?
Copper-Nickel 90/10 (UNS C70600) and Copper-Nickel 70/30 (UNS C71500), to the ASTM or ASME material specification stated in your order.
Where is Sunflex Metalloy located?
We are an India-based manufacturer with three manufacturing units in Gujarat, and we supply industrial buyers in the USA and international markets.
Which flange standards do you work to?
Dimensions are typically referenced to ASME B16.5 and B16.47, with other standards per project specification. Manufactured to applicable ASME/ASTM requirements based on project specification.
Can I send a drawing?
Yes. The enquiry form accepts PDF, DWG, DXF and STEP files, and we can quote non-standard flanges to drawing.