Copper Nickel Threaded Flange
A copper nickel threaded flange connects to an externally threaded pipe without a butt weld or slip-on attachment weld at the flange-to-pipe joint. Its internal thread screws onto the pipe end, while the bolted flange face connects to a matching flange, valve or equipment nozzle.
HC Aluminum supplies CuNi threaded flange configurations for marine, seawater and industrial piping projects, with material, dimensions, thread type, pressure class and face configuration produced according to the specified project requirements.
- C70600 CuNi 90/10
- C71500 CuNi 70/30
- ASME B16.5
- Class 150
- Class 300
- NPT
- BSPT
- FF
- RF
- Material
- UNS C70600 · C71500
- Alloy
- CuNi 90/10 · CuNi 70/30
- Dimension
- ASME B16.5
- Size
- NPS 1/2–24, as specified
- Thread
- NPT · BSPT
- Pressure Class
- Class 150 · Class 300
- Face
- Flat Face (FF) · Raised Face (RF)
- Manufacturing
- Forged · Machined · As specified
What Is a Copper Nickel Threaded Flange?
A copper nickel threaded flange is a flanged connection designed for pipe systems where the flange is joined to the pipe by threads rather than welding. The flange has an internal thread, while the pipe or threaded fitting has a matching external thread. During installation, the two parts are screwed together to form the connection.
This design can be useful where welding is restricted, hot work needs to be avoided, or the piping section may need to be dismantled for maintenance. Unlike a slip-on or weld neck flange, no flange-to-pipe weld is needed. The final connection still depends on accurate thread matching, proper bore dimensions, flange rating and sealing-face selection.
For a complete copper nickel piping system, the flange should be specified together with the pipe material, NPS or DN, pressure class and applicable standard. HC Aluminum supplies copper nickel flanges in C70600 CuNi 90/10 and C71500 CuNi 70/30, with configurations manufactured according to project requirements and drawings. Where pipe matching is required, the flange dimensions can also be checked against the corresponding copper nickel pipe specification.
Copper Nickel Threaded Flange Specifications
HC Aluminum supplies copper nickel threaded flanges in C70600 and C71500 for piping connections where a screwed, non-welded flange arrangement is required. Dimensions, thread form, pressure class and facing can be specified according to the mating pipe and project requirements.
| Product | Copper nickel threaded flange / CuNi screwed flange |
| Material | UNS C70600 CuNi 90/10 or UNS C71500 CuNi 70/30 |
| Material specification | ASTM B151/B151M where applicable to the specified copper nickel rod or bar starting material |
| Flange standard | ASME B16.5, with the applicable edition confirmed during order review |
| Nominal size | NPS 1/2–24 |
| Pressure class | ASME B16.5 Class 150 or Class 300 |
| Thread type | NPT to ASME B1.20.1 requirements; BSPT available with the applicable ISO 7-1 / EN 10226 designation confirmed before production |
| Flange facing | Flat Face (FF) or Raised Face (RF), according to the mating flange and piping specification |
| Manufacturing | Machined from specified copper nickel material, with bore, thread, face and dimensional requirements checked against the approved specification |
| Inspection | Dimensional inspection, thread gauging and material certification; additional inspection or testing can be arranged when required by the purchase order |
| Documentation | Material certificate and inspection documentation available according to the agreed order requirements |
| MOQ | MOQ: production quantities are confirmed according to size, alloy, machining requirements and order specification |
| Packaging | Export seaworthy packaging with individual surface protection, thread protection where required, and plywood cases or pallets selected according to flange size and shipment method |
| Custom requirements | Drawing-based dimensions, special thread requirements, facing details, marking, inspection plans and packing instructions can be reviewed before production |
C70600 vs C71500 Copper Nickel Threaded Flanges
HC Aluminum manufactures copper nickel threaded flanges in UNS C70600 and C71500. Both grades are used for copper nickel piping, but their nickel content and project requirements are different. The correct grade should be matched with the pipe material, design specification and applicable flange standard rather than selected by alloy name alone.
C70600 CuNi 90/10
UNS C70600 is a 90/10 copper nickel alloy with approximately 90% copper and 10% nickel. It is commonly specified for marine piping, seawater service and cooling-water systems where copper nickel's resistance to seawater corrosion is required.
- Alloy: CuNi 90/10
- UNS: C70600
- Typical service: marine, seawater and cooling-water piping
- Composition: copper-nickel alloy with applicable iron and manganese additions
- Flange supply: threaded configuration manufactured to the required size, face and piping specification
For a broader range of C70600 components, see our Copper Nickel 90/10 Flanges product range.
C71500 CuNi 70/30
UNS C71500 is a 70/30 copper nickel alloy containing approximately 70% copper and 30% nickel. It is used for marine, offshore and industrial piping systems where the project specification calls for CuNi 70/30 material.
- Alloy: CuNi 70/30
- UNS: C71500
- Typical service: marine, offshore and industrial piping
- Composition: higher nickel content than C70600, with applicable alloying additions
- Flange supply: threaded configuration produced according to the specified dimensions and piping requirements
See our Copper Nickel 70/30 Flanges page for additional C71500 flange information.
Material selection: C70600 and C71500 should not be treated as automatic substitutes for one another. HC Aluminum can manufacture the threaded flange according to the specified UNS grade, flange dimensions, pressure class, thread type and face configuration provided in the project requirements.
Copper Nickel Threaded Flange Size Chart
ASME B16.5 CL 150 Copper Nickel Threaded Flange Size Chart
| specification | d1 | A | H | C | X | R | E | G | N-Od2 | Weight |
| inch | mm | mm | mm | mm | mm | mm | mm | mm | kg | |
| 1/2" | 21.3 | 88.9 | 15.9 | 11.2 | 30.2 | 34.9 | 1/2"FNPT | 60.3 | 4-15.9 | 0.80 |
| 3/4" | 26.7 | 98.4 | 15.9 | 12.7 | 38.1 | 42.9 | 3/4"FNPT | 69.8 | 4-15.9 | 1.10 |
| 1" | 33.4 | 107.9 | 17.5 | 14.3 | 49.2 | 50.8 | 1"FNPT | 79.4 | 4-15.9 | 1.20 |
| 11/4" | 42.2 | 117.5 | 20.6 | 15.9 | 58.7 | 63.5 | 11/4"FNPT | 88.9 | 4-15.9 | 1.50 |
| 11/2" | 48.3 | 127 | 22.2 | 17.5 | 65.1 | 73 | 11/2"FNPT | 98.4 | 4-15.9 | 1.60 |
| 2" | 60.3 | 152.4 | 25.4 | 19.1 | 77.8 | 92.1 | 2"FNPT | 120.6 | 4-19 | 2.70 |
| 21/2" | 73 | 177.8 | 28.6 | 22.2 | 90.5 | 104.8 | 21/2"FNPT | 139.7 | 4-19 | 4.10 |
| 3" | 88.9 | 190.5 | 30.2 | 23.8 | 107.9 | 127 | 3"FNPT | 152.4 | 4-19 | 5.10 |
| 4" | 114.3 | 228.6 | 33.3 | 23.8 | 134.9 | 157.2 | 4"FNPT | 190.5 | 8-19 | 7.00 |
ASME B16.5 CL 300 Copper Nickel Threaded Flange Size Chart
| specification | d1 | A | H | C | X | R | E | G | N-Qd2 | Weight |
| inch | mm | mm | mm | mm | mm | mm | mm | mm | kg | |
| 1/2" | 21.3 | 95.2 | 22.2 | 14.3 | 38.1 | 34.9 | 1/2"FNPT | 66.7 | 4-15.9 | 0.90 |
| 3/4" | 26.7 | 117.5 | 25.4 | 15.9 | 47.6 | 42.9 | 3/4"FNPT | 82.5 | 4-19 | 1.40 |
| 1" | 33.4 | 123.8 | 27 | 17.5 | 54 | 50.8 | 1"FNPT | 88.9 | 4-19 | 1.70 |
| 11/4" | 42.2 | 133.3 | 27 | 19 | 63.5 | 63.5 | 11/4"FNPT | 98.4 | 4-19 | 2.00 |
| 11/2" | 48.3 | 155.6 | 30.2 | 20.6 | 69.8 | 73 | 11/2"FNPT | 114.3 | 4-22.2 | 3.00 |
| 2" | 60.3 | 165.1 | 33.3 | 22.2 | 84.1 | 92.1 | 2"FNPT | 127 | 8-19 | 3.40 |
| 21/2" | 73 | 190.5 | 38.1 | 25.4 | 100 | 104.8 | 21/2"FNPT | 149.2 | 8-22.2 | 5.10 |
| 3" | 88.9 | 209.5 | 42.9 | 28.6 | 117.5 | 127 | 3"FNPT | 168.3 | 8-22.2 | 6.80 |
| 4" | 114.3 | 254 | 47.6 | 31.8 | 146.1 | 157.2 | 4"FNPT | 200 | 8-22.2 | 11.30 |
Copper Nickel Flange Thread Options: NPT, BSPT and BSPP
- NPT: American National Standard Taper Pipe Thread with a 60° thread form. Specify the nominal pipe size, male or female thread, and the applicable ASME B1.20.1 requirements.
- BSPT: British Standard Pipe Taper thread with a 55° thread form. For a female tapered connection, confirm whether the required thread is Rc and identify the applicable standard before production.
- BSPP: Parallel pipe thread, normally identified as G. It is different from BSPT and should not be substituted unless the complete connection design permits a parallel-thread arrangement.
For flange and pipe matching, nominal size alone is not always enough. Check the actual outside diameter, wall thickness, thread designation, and mating connection of the copper nickel pipe. These details help confirm the required bore and thread configuration before the flange is manufactured.
Copper Nickel Flange Face Options: FF vs RF
Flat Face (FF)
A Flat Face flange keeps the sealing surface level with the full flange face. FF is used when the piping specification calls for a flat-face joint and the mating flange, gasket, and bolting arrangement are designed for it.
- Flat sealing surface across the flange face
- Used with a matching FF connection
- Gasket type and dimensions are determined by the piping specification
- Commonly specified for applications requiring a full flat-face arrangement
Raised Face (RF)
A Raised Face flange has a machined sealing area raised above the surrounding flange face. RF is a common configuration for ASME flange connections, with the face finish, gasket, and mating flange selected as one connection set.
- Raised sealing surface above the flange body
- Common configuration for ASME flange assemblies
- Mating flange face and dimensions must be properly matched
- Gasket selection should follow the applicable piping or project specification
Class 150 and Class 300 Copper Nickel Threaded Flanges
Class 150
Class 150 is used for piping systems designed around the corresponding ASME flange dimensions and pressure-temperature requirements. The final pressure capability depends on the specified material and service temperature.
- ASME B16.5 Class 150 dimensions
- NPT or BSPT thread configuration as specified
- FF or RF flange face options
- C70600 or C71500 material selection
Class 300
Class 300 follows the higher ASME pressure-class configuration and corresponding dimensional requirements. Material grade, temperature, thread form, and sealing arrangement still need to be defined for the actual service.
- ASME B16.5 Class 300 dimensions
- NPT or BSPT thread configuration as specified
- FF or RF flange face options
- C70600 or C71500 material selection
Inspection and Documentation for Copper Nickel Threaded Flanges
Material Verification
- C70600 or C71500 grade verification
- Chemical composition review
- PMI when required
- Heat number identification and traceability
Dimensional Inspection
- Outside diameter and flange thickness
- Bore diameter
- Bolt-hole diameter and quantity
- Bolt circle and key drawing dimensions
Thread Inspection
- NPT or BSPT thread identification
- Nominal thread size and pitch verification
- Go / No-Go gauge checking where applicable
- Internal thread profile and machined condition
Face and Surface Check
- FF or RF face configuration
- Sealing-face condition
- Machined surface appearance
- Visual inspection for surface defects
Additional NDT
- Liquid penetrant testing (PT) when specified
- Ultrasonic testing (UT) where required
- Other inspection methods according to the project requirement
- Third-party inspection support when arranged
Inspection Records
- EN 10204 3.1 MTC when specified
- Dimensional inspection records
- Material and heat-number traceability records
- Final inspection and release documentation
Applications of Copper Nickel Threaded Flanges
Copper nickel flange applications are generally associated with piping systems where the specified copper nickel alloy, connection method and project standards are suitable for the service conditions.
Marine Piping
Used in shipbuilding and marine piping systems such as seawater cooling, auxiliary seawater and related piping where copper nickel materials are specified.
Offshore Systems
Used for selected offshore seawater and utility piping applications where CuNi materials and threaded connections are included in the project design.
Desalination
Applied in selected seawater intake, treatment and cooling systems where the material and flange specification requires copper nickel.
Industrial Cooling
Used in specified seawater, brine or saline-water cooling arrangements in industrial facilities and power-related installations.
How Is a Threaded Copper Nickel Flange Connected to Pipe?
The flange bore is machined with an internal pipe thread, while the mating pipe is prepared with the corresponding external thread. During assembly, the pipe is screwed into the flange until the specified engagement and position are achieved.
Thread compatibility, engagement length, sealing method and pipe wall thickness should be checked before installation.
Copper Nickel Threaded Flange vs. Slip-On Flange
The main difference is how the flange attaches to the pipe. A threaded flange uses an internal screw thread; a slip-on flange passes over the pipe and is attached by welding.
| Comparison | Threaded Flange | Slip-On Flange |
| Pipe attachment | Screws onto an externally threaded pipe end | Slides over the pipe and is normally secured with fillet welds |
| Welding at attachment joint | Not normally required for the basic screwed connection | Required |
| Pipe preparation | Correct external thread and adequate remaining wall | Suitable pipe end preparation and weld fit-up |
| Attachment sealing | Depends on thread fit and the approved sealing method | Depends on the specified weld detail and weld quality |
| Installation constraint | Requires controlled thread engagement and make-up | Requires welding access and an approved welding procedure |
| Reuse or modification | May be unscrewed if condition and access permit | Changes usually involve cutting and rewelding |
| Selection concerns | Thread-root wall thickness, vibration, cycling and leakage risk | Weld integrity, inspection access and service requirements |
Choose a threaded design only when screwed joints are permitted by the piping specification. For welded pipework, compare the connection requirements on our Copper Nickel Slip-On Flange page.
For other joint arrangements, see the Copper Nickel Flanges range.
How to Match Copper Nickel Pipe with a Threaded Flange
A threaded flange should be selected from the actual pipe connection details, not from flange size alone. The pipe size, copper nickel grade, pipe dimensions, thread form, pressure class and flange face all need to correspond before the connection is released for fabrication or installation.
Pipe Size
Start with the pipe NPS or DN and select the threaded flange with the same nominal size. The nominal size identifies the connection size; it does not by itself confirm that the pipe and flange are compatible.
Copper Nickel Grade
Match the flange material with the pipe grade specified for the system. For C70600 CuNi 90/10 piping, see our 90/10 copper nickel pipe. Projects using C71500 CuNi 70/30 can be matched with our 70/30 copper nickel pipe.
Thread and Pipe Dimensions
The flange bore and pipe thread must use the specified thread system, such as NPT or BSPT. Pipe outside diameter, wall thickness and available thread engagement should also be checked so the threaded section is suitable for the selected flange.
Class and Flange Face
Verify the required ASME pressure class and flange face before ordering. Class 150 and Class 300 are different flange ratings, while FF and RF define different facing arrangements. The pipe, flange and mating connection should be specified as one complete assembly.
When additional threaded components are required, the matching pipe connection can also be reviewed together with our copper nickel threaded pipe fittings. This is useful when the piping package includes elbows, tees, adapters or other threaded CuNi components that need to follow the same alloy and thread requirements.
Copper Nickel Flanges, Pipe and Fittings
A threaded flange is only one part of a copper nickel piping connection. HC Aluminum also supplies matching CuNi flanges, seamless and welded pipe, and threaded fittings in the grades commonly used for marine and industrial piping.
Copper Nickel Flanges
See the full copper nickel flange range, including threaded, slip-on, blind and other flange configurations.
Copper Nickel 90/10 Flanges
C70600 CuNi 90/10 flanges for piping systems using 90/10 copper nickel components.
Copper Nickel 70/30 Flanges
C71500 CuNi 70/30 flanges for applications where the 70/30 alloy is specified.
90/10 Copper Nickel Pipe
C70600 pipe for use with matching 90/10 copper nickel flanges and fittings.
70/30 Copper Nickel Pipe
C71500 pipe for piping systems specified with CuNi 70/30 components.
CuNi Threaded Pipe Fittings
Related threaded fittings for connecting copper nickel pipe with compatible threaded components.
FAQ – Copper Nickel Threaded Flanges
Does a copper nickel threaded flange need welding?
The basic flange-to-pipe connection is made by threading rather than welding. Whether this arrangement is permitted depends on the applicable piping code and project specification. A seal weld should not be added as an informal remedy for an unsuitable threaded joint.
Can I use a threaded flange on thin-wall copper nickel pipe?
Not without checking the remaining wall thickness after threading and the applicable design requirements. Pipe suitable for a welded connection is not necessarily suitable for an external pipe thread.
Are NPT and BSPT copper nickel flanges interchangeable?
No. NPT and BSPT have different thread forms and must match the specified mating pipe connection. Do not rely on partial engagement as proof of compatibility.
Should I select a flat-face or raised-face flange?
Match the flange facing to the mating component, gasket arrangement and applicable specification. In particular, do not assume an RF flange can be bolted to an FF component without checking the permitted joint arrangement.
Does ASTM B151 certify the finished flange?
ASTM B151/B151M can define applicable rod or bar material requirements. Finished-flange conformity also involves dimensions, manufacturing requirements, inspection and the relevant service or design requirements.
The following copper nickel products may interest you
Further reading: Copper Nickel PipesCopper Nickel ElbowsCopper Nickel TeesCopper Nickel ReducerCopper Nickel Pipe CapCopper Nickel FlangesCopper Nickel Threaded Pipe Fittings