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Marine biofouling is resisted by the copper nickel alloy in a way in which neither stainless nor titanium alloys succeed in doing since the copper ions leaking out of the alloy prevent the organisms from attaching on to it which would obstruct the seawater system. That same surface sets the design limit, since flow above a few metres per second strips the protective film. Copper nickel 90/10 pipes and tubes to UNS C70600 carry about 10% nickel with iron and manganese additions. They are the standard choice for seawater cooling and firewater systems at plants across Oman. Related grades are on the copper nickel and titanium pipes and tubes hub.
Where Copper Nickel 90/10 Is Used
- Seawater cooling water lines and headers
- Firewater ring mains on offshore platforms and coastal plants
- Condenser and heat exchanger tubes in seawater service
- Desalination plant seawater piping
- Shipbuilding and marine service lines
Where flow velocity or erosion is higher, copper nickel 70/30 is specified instead. For very aggressive chlorides at high temperature, titanium grade 2 is the alternative.
Velocity, Film Formation and Commissioning
| Factor | Why it matters |
|---|---|
Flow velocity | Above the design limit for the alloy, the protective film is stripped and erosion corrosion begins. 90/10 has a lower limit than 70/30 |
Initial film formation | The protective layer forms over the first weeks in clean flowing seawater; commissioning practice affects long-term performance |
Stagnant polluted seawater | Sulphides in stagnant or polluted water attack copper nickel, so lines should not be left full and idle |
Entrained sand and solids | Accelerate erosion at bends and downstream of restrictions |
Biofouling | Copper ions discourage settlement, which is the alloy's main advantage over stainless in seawater |
Two practical rules follow. Size the line so velocity stays within the limit set for the grade, paying attention to bends, tees and pump suctions where local velocity rises. And commission with clean seawater flowing rather than leaving the system stagnant, so the protective film forms properly before the plant goes into service.
Seawater Performance and Limits
Copper nickel 90/10 resists seawater corrosion and biofouling well within its velocity limit, and it tolerates chlorides that would pit austenitic stainless. Its weaknesses are erosion corrosion above the velocity limit, attack in stagnant polluted water containing sulphides, and poor resistance to ammonia and to strongly oxidising conditions. It is not a sour service material for hydrocarbon systems. State your velocity, temperature and water quality in the RFQ; requirements are confirmed at quotation.
Copper Nickel 90/10 Price Factors
Each enquiry is quoted individually, since alloy surcharges move week to week. What changes the figure:
- Grade and alloy content
- Product form, size and wall
- Finish, cleaning and passivation
- Supplementary tests and PMI
- Order quantity against mill minimums
- Stock or mill order
- Certificate level and inspection scope
- Delivery terms and destination port
Quotations are available in USD, OMR, AED, SAR, QAR, KWD and BHD, on EXW, FOB, CFR or CIF terms.
What to send for a quotation:
grade, standard, seamless or welded, NPS or OD, schedule or wall, length, quantity, finish, testing, the design flow velocity, certification, inspection, destination port and required date.
Certification, PMI and Inspection
Material comes with EN 10204 3.1 certificates as standard, and EN 10204 3.2 certificates on request. Inspection by the buyer's nominated third-party agency can be arranged; state your requirement in the RFQ. For Copper Nickel 90/10, review the chemistry, annealing details and mechanical results, and specify PMI so each item is verified before it goes into the line. See the MTC and EN 10204 certification guide.
Handling Copper Nickel 90/10 on Site
Lead time is confirmed at quotation. Pipe and tube arrive capped, and wrapped where the finish requires it. Store on timber or plastic, not on carbon steel, and use dedicated slings, brushes and grinding discs. Salt-laden coastal air leaves deposits on stored material, so a rinse before welding is worth the time.
Fittings and Related Grades
Copper nickel fittings and flanges are supplied to matching standards for seawater systems.
- Copper nickel 70/30 pipes and tubes
- Copper nickel 95/5 pipes and tubes
- Titanium grade 2 pipes and tubes
Copper nickel 90/10 is used across desalination and water treatment, marine and offshore and power generation seawater systems.
Copper Nickel 90/10 FAQ
Why is copper nickel used for seawater?
It resists seawater corrosion and discourages biofouling, since copper ions at the surface deter organisms from settling.
What is the velocity limit?
Copper nickel systems are designed to a maximum seawater velocity for the grade, with 90/10 lower than 70/30. Exceeding it causes erosion corrosion.
What happens in stagnant seawater?
Sulphides in stagnant or polluted water attack copper nickel, so systems should not be left full and idle.
How strong is C70600?
Minimum tensile strength 262 MPa and minimum yield 90 MPa, so wall thickness is often governed by handling and erosion rather than pressure.
What is the EN equivalent?
CuNi10Fe1Mn, material CW352H.
What should I send for a quotation?
Send the UNS number, form, OD, wall, length, quantity, design velocity and water conditions, certification and destination port.
Request a Quote for Copper Nickel 90/10 Pipes and Tubes (UNS C70600)
Send the OD, wall, length and quantity, with the design velocity and water quality. Every enquiry is checked before the offer is prepared, so a line sized above the velocity limit is raised at the start.