In modern industry and marine engineering, seawater piping systems serve as vital links between offshore resources and onshore infrastructure. To ensure long-term, reliable operation in harsh seawater environments, selecting the right piping connection components is essential.

The C70600 Copper Nickel Welding Neck Flange PN16 DN100 is a high-performance connection component specifically designed for seawater piping systems. With outstanding corrosion resistance, mechanical strength, and dependable sealing performance, it is an ideal choice for marine engineering applications.

Product Overview

MC PiPE offers C70600 copper-nickel weld neck (WN) flanges—specifically the PN16 DN100 model—designed for copper-nickel seawater piping systems. The flange body is forged from a single piece of UNS C70600 (CuNi 90/10) alloy, with a chemical composition meeting specifications of 9.0–11.0% Ni, 1.0–1.8% Fe, and 0.5–1.0% Mn. This allows for butt-welding to C70600 piping using the same material, fundamentally eliminating the risk of galvanic corrosion associated with dissimilar metals. The weld neck design offers superior stress distribution compared to slip-on flanges, making it ideal for seawater pipeline connections subject to temperature fluctuations, pressure pulsations, and pipeline stresses.

The flange dimensions and pressure ratings strictly adhere to major international standards. The PN16 rating corresponds to a nominal pressure of 16 bar (approx. 232 psi), while the DN100 (4-inch) nominal bore is one of the most common sizes in seawater piping systems. The weld end outer diameter of 114.3 mm perfectly matches C70600 piping; connection dimensions and sealing face parameters comply with DIN 86037, ASME B16.5, or EN 1092 standards, supporting both Raised Face (RF) and Flat Face (FF) configurations.

Welding Neck Flange Structure and Advantages

A welding neck flange is a flange type designed for applications requiring high connection reliability. It features a long, tapered hub, and the flange neck is typically connected to the pipe by butt welding.

Compared with slip-on flanges, lap joint flanges, and other flange types, the C70600 welding neck flange offers the following advantages:

1. More Even Stress Distribution

The tapered hub of the welding neck flange allows a smoother stress transition between the flange and the pipe, helping reduce local stress concentration at the connection area.

For seawater transportation, pump outlet lines, seawater cooling circulation systems, and pipelines exposed to long-term vibration, this structure provides greater reliability.

2. Suitable for Long-Term Seawater Piping Service

Seawater systems often operate continuously and may be exposed to pressure fluctuations, temperature changes, and equipment vibration. Welding neck flanges offer good fatigue resistance and are suitable for piping locations that require high sealing performance and long-term operational stability.

3. Convenient for Non-Destructive Testing and Weld Quality Control

Welding neck flanges are generally connected by butt welding. Depending on project requirements, welds can be inspected by radiographic testing, ultrasonic testing, liquid penetrant testing, or other inspection methods.

This helps marine engineering projects achieve more stringent weld quality control.

4. Reduced Leakage Risk

When properly matched with suitable gaskets, bolts, and tightening procedures, welding neck flanges provide a stable and reliable sealed connection for seawater piping systems, reducing the risk of leakage during long-term operation.

C70600 Copper Nickel Flange Technical Specifications

To meet demanding marine engineering requirements, C70600 copper-nickel welding neck flanges are manufactured with strict control over dimensional tolerances, pressure capacity, and chemical composition in accordance with international standards such as DIN 86037, EN 1092-1, ASME B16.5, and EEMUA 145.

Key Advantages of C70600 Copper Nickel Welding Neck Flanges

Excellent Seawater Corrosion Resistance

Seawater contains chloride ions, dissolved oxygen, salts, and various microorganisms. Ordinary metal materials can corrode rapidly under such conditions.

C70600 copper-nickel alloy provides excellent resistance to natural seawater, flowing seawater, and marine atmospheric environments. It is especially suitable for seawater transfer pipelines and circulating cooling systems.

Strong Erosion-Corrosion Resistance

At pump outlets, bends, throttling sections, and higher-velocity pipeline areas, materials are exposed not only to chemical corrosion but also to fluid erosion.

C70600 copper-nickel alloy has excellent resistance to erosion-corrosion and is suitable for seawater piping systems operating within properly designed flow velocity ranges.

Resistance to Marine Biofouling

Copper-nickel alloys have a natural ability to resist marine organism attachment in seawater environments. This can help reduce biofouling caused by barnacles, mussels, algae, and other marine organisms.

As a result, C70600 flange connections can help lower maintenance costs and reduce the risk of pipeline blockage.

Good Weldability and Fabrication Performance

C70600 offers good weldability and is suitable for the manufacture of welding neck flanges, pipe fittings, pipes, and heat exchanger components.

Actual welding procedures should be performed according to material thickness, approved welding procedure specifications, matching filler materials, and project standards.

Long Service Life and Lower Lifecycle Cost

Although the initial material cost of copper-nickel alloys is generally higher than carbon steel, C70600 flanges can reduce the total cost associated with frequent maintenance, replacement, and unplanned shutdowns in high-salinity, high-humidity, and long-term seawater service environments.

From a lifecycle cost perspective, copper-nickel flanges offer strong engineering value.

Typical Applications

Marine Seawater Cooling Systems

Used with copper-nickel piping in seawater cooling circuits for main engines and auxiliary engines, connecting coolers, pumps, valves, and heat exchange equipment.

Seawater Desalination Plants

Suitable for pretreatment piping and concentrated brine discharge lines in reverse osmosis and thermal desalination systems, where long-term resistance to highly saline water is required.

Offshore Platforms and FPSO Systems

Used in firewater systems, ballast water systems, and seawater injection pipelines on offshore oil and gas platforms and floating production storage and offloading vessels.

Coastal Power Plants

Used as a reliable connection component between pipelines, condensers, and circulating water pumps in seawater cooling lines for power plant condensers.

Installation Recommendations

To ensure the long-term performance and reliability of C70600 copper-nickel welding neck flanges, the following installation guidelines are recommended:

1.Surface Preparation

Before welding, clean oil, grease, dirt, and oxide layers from the flange and pipe surfaces to ensure weld quality.

2.Welding Procedure

Use appropriate welding current, travel speed, and welding parameters. Avoid excessive heat input or overly rapid cooling to ensure the integrity of the welded joint.

3.Sealing

Use suitable ring gaskets or soft sealing gaskets, and ensure that the flange faces are properly aligned without gaps or damage.

4.Inspection

After welding, use non-destructive testing methods, such as ultrasonic testing, radiographic testing, or other specified inspection methods, to verify weld quality.

Why Choose Our C70600 Copper Nickel Flanges?

Reliable and Genuine Material

We use certified C70600 copper-nickel alloy billets from qualified mills. Chemical composition and mechanical properties are verified through spectrometer analysis and tensile testing, preventing the use of low-nickel or inferior copper alloys as substitutes.

Comprehensive Standards Coverage

Our flanges can be manufactured in accordance with major standards including DIN, ASME, EN, and JIS. Custom manufacturing based on drawings and non-standard dimensions is also available.

Complete Range of Specifications

In addition to PN16 DN100, we supply C70600 welding neck flanges, slip-on flanges, and blind flanges in sizes from DN15 to DN600, supporting one-stop procurement for marine and seawater piping projects.

Controlled Delivery Lead Time

Common sizes can be supplied from stock, while special specifications can be scheduled for fast production to support your project timeline.

Professional Technical Support

We provide technical support for flange-to-pipe welding procedures, installation guidance, and material selection. Our technical team can assist in resolving on-site engineering issues.

We supply a complete range of C70600 (CuNi 90/10) copper-nickel flanges, pipe fittings, and matching pipes.

Contact our engineering and sales team today for detailed product drawings, real-time quotations, and volume purchase discounts.