What is C70600 Copper Nickel 90/10 (Cupronickel)?

C70600 Copper Nickel 90/10, also known as Cupronickel 90/10, is a copper alloy with a composition of approximately 90% copper and 10% nickel, along with trace amounts of iron and manganese. This alloy is extremely versatile and known for its high heat transfer, ductility, and corrosion resistance.

Cupronickel 90/10 is highly resistant to corrosion in seawater because its electrode potential is adjusted to be neutral with regard to seawater. It also has low macrofouling rates and good fabricability.

Copper-nickel alloys have provided reliable service for decades while offering effective solutions to today's technological challenges. C70600 is particularly desirable where high temperatures are encountered, as it has the property of forming protective films of corrosion products – making it especially desirable for service where water velocities are high.

C70600 exhibits excellent resistance to corrosion in various environments, especially:

Seawater

Brackish water

It is highly resistant to:

Biofouling (marine growth does not readily attach)

Erosion (can handle moderate water velocities)

Stress corrosion cracking (immune to chloride SCC)

Condenser tubes of C70600 are giving long and dependable service at sea. This alloy is also highly satisfactory for tubes in evaporators, inter-after condensers, air ejectors of steam condensers, and in boiler feedwater heaters.

Machinability: C70600 is known for its good machinability, allowing for ease of fabrication and machining processes. However, its high strength and work hardening characteristics may require appropriate machining techniques and tools.

Fabrication suitability for tube:

Bending: Good – annealed tube bends easily

Flaring / Expanding: Excellent – can be rolled into tube sheets

Welding: TIG, MIG, coated metal arc, butt, seam – all suitable

Annealing: 593 – 816°C (1100 – 1500°F)

C70600 is extensively used in the following industries and applications:

Q1: What is the difference between ASTM B111 C70600 tube and ASTM B466 C70600 pipe?
A: ASTM B111 C70600 tube is for heat exchangers and condensers – tighter tolerances, eddy current tested. ASTM B466 C70600 pipe is for general seawater piping – larger diameters, thicker walls, hydrostatic tested.

Q2: What is the melting point of C70600 copper nickel 90/10 tube?
A: C70600 tube has a melting point range of 1170 – 1240°C (2140 – 2260°F).

Q3: Can C70600 (90/10 cupronickel) tube be used for boiler feedwater heaters?
A: Yes, C70600 tube is highly satisfactory for tubes in boiler feedwater heaters, especially where high temperatures are encountered.

Q4: What is the typical elongation of annealed ASTM B111 C70600 tube?
A: Annealed C70600 tube typically has 25-35% elongation. This makes it suitable for bending, flaring, and expanding into tube sheets.

Q5: Is C70600 copper nickel 90/10 tube resistant to biofouling?
A: Yes, C70600 tube has excellent resistance to biofouling. Marine organisms do not readily attach to cupronickel surfaces, reducing maintenance costs.

Q6: What military specifications cover C70600 tube?
A: C70600 tube is covered by MIL-T-15005F and MIL-T-16420K (Classes 200, 700, 1650, 3300, and 6000).

Q7: Can C70600 (90/10 cupronickel) tube be used in desalination plants?
A: Yes, C70600 tube is extensively used in desalination plants for heat exchangers, tubing, and piping systems due to its resistance to both seawater corrosion and biofouling.

Q8: What is the yield strength of C70600 copper nickel 90/10 tube?
A: C70600 tube has a yield strength of 105 – 240 MPa (15,000 – 35,000 psi) depending on temper and manufacturing process.

Q9: Does C70600 tube require special welding techniques?
A: C70600 tube can be welded using standard TIG, MIG, or coated metal arc welding. Use AWS A5.7 ERCuNi filler metal for best corrosion resistance.

Q10: Is C70600 (90/10 cupronickel) tube suitable for offshore oil and gas platforms?
A: Yes, C70600 tube is suitable for offshore oil and gas applications including piping, tubing, and components in subsea systems, platforms, and pipelines.

Q11: What is the maximum operating temperature for ASTM B111 C70600 tube?
A: C70600 tube can operate continuously up to 300°C (572°F) in heat exchanger service.

Q12: How does C70600 copper nickel 90/10 tube compare to 316L stainless steel tube in seawater?
A: C70600 tube offers superior biofouling resistance and is immune to chloride stress corrosion cracking. 316L tube may pit and crack in seawater over time.

Q13: What forms of C70600 tube does GNEE supply?
A: GNEE supplies C70600 in seamless tube (ASTM B111), seamless pipe (ASTM B466), U-bend tubes, and straight cut lengths.

Q14: Is C70600 (90/10 cupronickel) tube used for automotive applications?
A: Yes, C70600 tube finds application in automotive cooling systems, specifically in radiators, heater cores, and oil coolers.

Q15: How is ASTM B111 C70600 tube inspected?
A: C70600 tube is inspected by chemical analysis, tensile testing, flattening test, expansion test, eddy current or hydrostatic testing, and dimensional inspection.

GNEE inspects C70600 tube through a 5-step process:

Chemical verification – Spectrometer checks Cu, Ni, Fe, Mn per ASTM B111

Mechanical testing – Tensile, yield, elongation, flattening, and expansion tests (sample basis)

Non-destructive testing (100%) – Eddy current (ASTM E243) or hydrostatic test per standard

Dimensional & visual check – OD, ID, wall thickness, length, surface finish, end condition

Documentation – Mill test report (MTR) with heat number traceability

Third-party inspection (SGS, BV, Lloyds) available upon request.

C70600 tube is packaged for export to prevent damage and corrosion:

Ends: Plastic caps on both ends

Protection: VCI paper wrap (for polished tubes) or rust-prevention oil

Bundling: Hexagonal bundles with steel strapping (3-5 straps)

Overwrap: Woven polypropylene or PE shrink film

Crating: Wooden crates or pallets (ISPM-15 compliant)

Labeling: Alloy, standard, dimensions, heat number, PO number

Bundle weight: 2000-2500 kg max | Tube length: 1m – 12m

GNEE manufactures C70600 tube using:

Certification: ISO 9001:2015 | Capacity: ~500 tons/month for C70600 tube

GNEE supplies all copper and copper alloy products across these categories:

All forms available: Seamless tube (2-219mm OD), pipe (1/8" – 12" NB), bar (2-300mm dia), plate (3-150mm thk), sheet, wire, strip, fittings, flanges, forgings, castings.

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