70/30 Copper Nickel Flanges – UNS C71500
HC Aluminum manufactures and supplies 70/30 copper nickel flanges for seawater, marine, desalination, offshore and industrial piping systems. Based on UNS C71500 copper-nickel alloy, we provide machined and forged flange solutions according to required dimensions, pressure class, flange type, material specification and project documentation.
With more than 20 years of experience in copper nickel alloy products, our capabilities include copper nickel pipe production, forging, flange machining, material inspection and export preparation for complete piping projects.
What Is 70/30 Copper Nickel?
70/30 copper nickel is a copper-nickel alloy containing approximately 70% copper and 30% nickel. The alloy is commonly designated UNS C71500 and is widely associated with marine, seawater and other demanding water-service applications.
The 70/30 designation describes the principal copper and nickel balance of the alloy. C71500 also contains controlled additions of iron and manganese within the specified chemistry to support the material's mechanical and corrosion-related performance.
C71500 Flange Specifications
| Item | Product Details |
| Material | 70/30 copper nickel |
| UNS designation | C71500 |
| Related designation | CuNi30Mn1Fe; confirm the applicable specification before substitution |
| Flange types | Weld-neck, slip-on, socket weld, blind and threaded |
| Dimensions and drilling | To the specified flange standard or an approved project drawing |
| Bore | Matched to the pipe outside diameter and wall thickness where applicable |
| Facing | Specified to suit the mating flange, gasket and service requirements |
| Applications | Seawater cooling, desalination, shipbuilding and offshore piping |
| Inspection and documents | Scope agreed according to the purchase order and project requirements |
70/30 Copper Nickel Flange Types
HC Aluminum can supply common flange configurations in C71500 according to the required piping design, connection method, dimensions and project specification.
Weld Neck Flanges
Weld neck flanges have a long tapered hub and are designed for butt-welding to the pipe. They are commonly selected where an integrated welded connection is required.
Slip-On Flanges
Slip-on flanges fit over the pipe end and are welded into position. They can be considered where a relatively simple flange installation and fabrication arrangement is required.
Blind Flanges
Blind flanges close a pipe section, nozzle or equipment connection. They can also allow a piping system to be isolated or opened later for inspection and maintenance.
Socket Weld Flanges
Socket weld flanges are designed for compatible smaller-diameter piping applications where socket-weld construction is specified.
Threaded Flanges
Threaded flanges connect to matching threaded pipe where a threaded construction is appropriate and welding is not required by the piping design.
Why C71500 Is Used in Seawater Systems
Seawater corrosion resistance
Under suitable operating conditions, copper nickel develops a protective surface film that helps resist corrosion in seawater.
Higher strength than 90/10 copper nickel
The higher nickel content generally gives C71500 greater strength than C70600, supporting its use where the project calls for 70/30 CuNi.
Resistance to flowing seawater
C71500 is selected for many flowing-seawater applications, but there is no single allowable velocity that applies to every system. Turbulence, entrained air, solids, temperature and piping geometry all affect performance.
Good fabrication characteristics
The alloy can be formed and welded using suitable procedures, making it practical for fabricated marine piping assemblies.
If your specification also permits 90/10 alloy, compare our 90/10 C70600 copper nickel flanges before confirming the grade.
70/30 Copper Nickel Flanges Chemical Composition
| KME CuNi70/30 | DIN 176642.0882 | BS 2871 CN107 | ASTM B466C71500 | JIS H3300C7150T | |
| Ni% | 30.0-32.0 | 30.0-32.0 | 30.0-32.0 | 29.0-33.0 | 29.0-33.0 |
| Fe% | 0.47-0.7 | 0.4-1.0 | 0.4-1.0 | 0.4-1.0 | 0.4-1.0 |
| Mn% | 0.5-1.0 | 0.5-1.5 | 0.5-1.5 | max.1.0 | 0.2-1.0 |
| C% | max.0.04 | max.0.05 | max.0.06 | max.0.05 | |
| Pb% | max.0.01 | max.0.03 | max.0.01 | max.0.02 | max.0.05 |
| S% | max.0.01 | max.0.02 | max.0.08 | max.0.02 | |
| P% | max.0.02 | max.0.02 | max.0.02 | ||
| Zn% | max.0.20 | max.0.50 | max.0.50 | max.0.50 | |
| Other | max.0.30 | max.0.30 | |||
| Cu% | rem. | rem. | rem. | rem. | +Ni+Fe+Mn min99.5 |
C71500 Fabrication Properties
| Fabrication Property | Typical Suitability |
| Soldering | Excellent |
| Brazing | Excellent |
| Oxyacetylene Welding | Good |
| Gas Shielded Arc Welding | Excellent |
| Coated Metal Arc Welding | Excellent |
| Spot Welding | Excellent |
| Seam Welding | Excellent |
| Butt Welding | Excellent |
| Cold Working | Good |
| Hot Forming | Good |
| Machinability Rating | 20 |
Where Are 70/30 Copper Nickel Flanges Used?
C71500 flanges are selected for piping systems where copper-nickel material performance is required in marine, seawater and related industrial environments.
Marine Piping
Used in shipboard piping systems where seawater exposure, corrosion resistance and reliable pipe connections are important considerations.
Seawater Cooling Systems
Applied to seawater cooling and associated piping systems where the material specification calls for copper-nickel alloy components.
Desalination Plants
Suitable for selected seawater intake, process-water and related piping applications in desalination facilities.
Water Treatment
Used in piping sections exposed to saline or aggressive water conditions where copper-nickel material is specified.
Offshore Oil and Gas
Applied to offshore seawater-handling and utility systems where C71500 is selected by the project engineering specification.
Shipbuilding and Marine Defense
Supplied for selected marine piping systems in commercial and defense-related shipbuilding projects according to applicable project requirements.
70/30 Copper Nickel vs 90/10 Copper Nickel
C71500 and C70600 are both copper-nickel alloy grades commonly associated with marine applications, but they have different copper-nickel compositions and should not be treated as interchangeable materials.
| Property | C71500 | C70600 |
| Copper-Nickel Ratio | 70/30 Copper-Nickel | 90/10 Copper-Nickel |
| Nickel Content | Higher | Lower |
| Common Positioning | 70/30 Copper-Nickel alloy | 90/10 Copper-Nickel alloy |
| Marine Service | Commonly used | Commonly used |
| Selection Basis | Project specification, corrosion conditions and design requirements | Project specification, corrosion conditions and design requirements |
Copper Nickel Flanges Quality Control
HC Aluminum applies a structured quality control process to 70/30 copper nickel flanges made from UNS C71500 copper nickel alloy. Each order is checked against applicable material specifications, dimensional requirements and project documentation before shipment.
- Material Verification Verify the copper nickel alloy grade, including UNS C71500, chemical composition and material certificates according to the agreed specification.
- Dimensional Inspection Check flange outside diameter, inside diameter, thickness, bolt hole diameter, bolt circle and overall dimensions against approved drawings.
- Surface Inspection Inspect flange faces, sealing surfaces, bolt holes and machined areas for visible defects, damage and surface quality requirements.
- Mechanical / Project Testing Arrange mechanical testing and additional project-specific inspections where required, with reports and documentation available according to the order requirements.
Why Source C71500 Flanges from HC Aluminum?
HC Aluminum has more than 20 years of experience in copper nickel products. With our own copper nickel pipe production facility, forging capability and in-house testing resources, we support the supply of 70/30 copper nickel flanges and related piping components for industrial and marine projects.
20+ Years of Copper Nickel Experience
HC Aluminum has produced and supplied copper nickel alloy pipes, marine flanges and related pipe fittings for more than 20 years. Our experience covers copper nickel materials used in seawater cooling, marine piping and industrial fluid-handling systems.
Own Copper Nickel Pipe Production Facility
Our own copper nickel pipe production facility supports material processing and coordination between pipes, flanges and other piping components. This helps us handle copper nickel piping requirements beyond a single flange order.
Forging Capability for Flange Blanks
Our forging capability supports the production of copper nickel flange blanks before machining. The forging route, material condition and subsequent processing can be arranged according to the required alloy, dimensions and applicable project specifications.
Flange Machining to Drawing Requirements
We support machining of key flange features, including bore diameter, outside diameter, thickness, bolt-hole arrangement and flange-facing details. Custom dimensions and drawing-based machining are available for approved requirements.
In-House Material Testing and Inspection
Our in-house testing resources support material verification and inspection of copper nickel products. Depending on the order requirements, inspection may cover chemical composition, mechanical properties, dimensions and surface condition, with relevant documentation supplied for review.
Export Packing and Project Documentation
HC Aluminum supports international orders with custom production, inspection documents and seaworthy export packing. We can coordinate flange supply with related copper nickel pipes and fittings when a project requires multiple piping components.
Need a complete copper nickel piping package? Explore our copper nickel pipe fittings alongside your required C71500 flanges, or contact HC Aluminum with your drawings, dimensions and inspection requirements.
FAQ – 70/30 Copper Nickel Flanges
Are 70/30 copper nickel and C71500 the same material?
UNS C71500 is commonly known as 70/30 copper nickel. However, “70/30” is a nominal alloy description. The purchase order should specify C71500 together with the applicable material standard and product requirements.
Is CuNi30Mn1Fe interchangeable with UNS C71500?
CuNi30Mn1Fe is commonly cross-referenced with 70/30 copper nickel. It should not be accepted as an automatic substitution based on the name alone. Compare the governing standards, chemistry, product form and mechanical requirements before approval.
Are C71500 flanges better than C70600 flanges?
C71500 generally offers higher strength, but it is not automatically the best choice for every seawater system. C70600 is also widely used in marine piping. The correct selection depends on service conditions, the piping specification, existing materials and cost.
Can C71500 flanges be welded to copper nickel pipe?
Yes, when the joint design, material combination and welding procedure are suitable. For weld-neck flanges, provide the pipe OD and wall thickness so the bore and weld end can be checked.
Can I order a flange from a drawing?
Send the drawing with the material grade, quantity, design requirements and inspection scope. HC Aluminum will review the dimensions and manufacturing requirements before confirming supply.
What flange types are available in C71500?
HC Aluminum can supply blind, slip-on, weld neck, socket weld and other flange configurations according to the required design, dimensions and application.
Are C71500 flanges suitable for seawater?
C71500 is commonly used in copper-nickel marine applications because of the alloy family's established seawater corrosion performance. Actual suitability depends on seawater chemistry, flow conditions, temperature and overall system design.
Can C71500 flanges be supplied with copper nickel pipes and fittings?
Yes. HC Aluminum can support related copper-nickel piping requirements with pipes, flanges and pipe fittings for marine, seawater and offshore projects.
What information should I provide when requesting a quotation?
The most useful information includes flange type, nominal size, pressure class, material designation, quantity, applicable standard, drawing and intended application. Providing a complete specification helps us review production and documentation requirements before quotation.
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