C70600 copper-nickel pipe fittings—also known as 90/10 copper-nickel fittings or CuNi 90/10 fittings—are corrosion-resistant components designed for piping systems that transport seawater, brine, cooling water, or other corrosive media. Designated as UNS C70600 (often referred to as CuNi10Fe1Mn in European standards), this material consists primarily of copper with approximately 10% nickel, along with additions of iron and manganese. These elements enable the formation of a stable protective film when exposed to seawater environments. Common C70600 pipe fittings include 45°, 90° and 180° elbows; equal and reducing tees; concentric and eccentric reducers; as well as slip-on (plate-type) flanges, weld-neck flanges, socket-weld flanges, and 5K/10K slip-on flanges. Also available are pipe caps, hex-head plugs, BSP/NPT threaded fittings, and threaded nipples. Custom, non-standard dimensions and specific flange drilling patterns can also be produced according to your drawings.

Typical Chemical Composition of C70600

As a copper-nickel-iron alloy, C70600 typically features the following chemical composition range:

Ni (including Co): 9.0%–11.0%

Fe: 1.0%–1.8%

Mn: ~1.0% (maximum)

Cu: Balance

The inclusion of iron enhances the material's resistance to erosion-corrosion in high-velocity seawater flow. Specific chemical composition limits shall be governed by ASTM, EN, or MIL standards, project-specific material specifications, and the Material Test Certificate (MTC).

Why are 90/10 copper-nickel fittings chosen for seawater systems?

- Excellent resistance to seawater corrosion

C70600 exhibits superior corrosion resistance in natural seawater, marine atmospheres, brackish water, and circulating cooling seawater. It is well-suited for marine seawater cooling piping, seawater intake and discharge systems, desalination plants, and auxiliary systems on offshore platforms.

- Resistance to flow-induced corrosion and erosion

In seawater piping systems, components such as elbows, tees, and reducers are susceptible to localized erosion caused by flow velocity fluctuations, turbulence, or the presence of solid particles. When operated within appropriate flow velocity, fluid cleanliness, and system design parameters, C70600 demonstrates excellent resistance to erosion-corrosion, making it an ideal material for piping fittings.

- Good weldability and fabricability

C70600 can be joined using appropriate welding processes, such as TIG or MIG welding. It can also be fabricated into fittings through cold forming, hot forming, or machining. The selection of filler materials, preheating requirements, heat input, and post-weld cleaning must be determined in accordance with the Welding Procedure Specification (WPS) and Procedure Qualification Record (PQR) to minimize the risk of corrosion in the weld zone.

Common standards and manufacturing methods

Seamless and welded C70600 pipes are covered by material standards such as ASTM B466/B466M and ASTM B467/B467M. The dimensions of butt-weld fittings generally conform to ASME B16.9, while socket-weld or threaded fittings may be specified according to requirements such as those in ASME B16.11.

Fittings can be produced via cold-pushing or hot-pressing of seamless pipes, machining, or fabrication from plates or pipes. For seawater and critical fluid systems, the purchaser should clearly specify whether fabricated (welded) structures are permitted, as well as requirements for weld inspection, pickling and passivation, pressure testing, and non-destructive testing (NDT).

Key Considerations for Procuring C70600 Pipe Fittings

When requesting a quote, please provide the following details: nominal pipe size (NPS/DN), wall thickness (or Schedule), connection type, dimensional standard, pressure rating, quantity, and the nature of the medium. For seawater-related projects, it is also necessary to specify the design flow velocity, operating temperature, chlorine content, and the presence of any sediment or particulate matter. Additionally, please indicate requirements for Positive Material Identification (PMI), chemical composition reports, mechanical property reports, hydrostatic testing, and third-party inspection documentation.

Haomei primarily supplies C70600 pipe fittings with certification. If you are sourcing C70600 copper-nickel fittings for a seawater piping project, please provide your parts list and drawings; we will promptly respond with a quotation and samples.