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The main basis for the preference of copper nickel 70/30 over copper nickel 90/10 is not corrosion but flow. An example would be pumps, tight bends, or condenser inlets where a very local velocity exceeds the pipeline average, and the greater reliability of nickel is called for. So, it is erosion rather than chemistry that is responsible for that change. The extra nickel raises both strength and velocity tolerance. They serve condensers, high-flow seawater lines and marine systems at plants across Oman. Related grades are on the copper nickel and titanium pipes and tubes hub.
Where Copper Nickel 70/30 Is Used
- Condenser and heat exchanger tubes in seawater cooling
- High-velocity seawater lines and pump suction piping
- Desalination plant heat recovery and brine heater tubing
- Marine and naval service systems
- Sections of a 90/10 system exposed to higher local velocity
For general seawater service, copper nickel 90/10 is more economical. Where chlorides and temperature exceed copper nickel limits, titanium grade 2 is used.
Choosing Between 90/10 and 70/30
| Factor | 90/10 (C70600) | 70/30 (C71500) |
|---|---|---|
Nickel | 9 to 11% | 29 to 33% |
Tolerance of flow velocity | Lower | Higher, which is the usual reason for specifying it |
Strength | 262 MPa tensile, 90 MPa yield | 372 MPa tensile, 138 MPa yield |
Resistance to erosion at bends and inlets | Good within its limit | Better, particularly where sand or entrained air is present |
Relative cost | Lower | Higher, from the nickel content |
Biofouling resistance | Good | Good |
Many seawater systems use both: 90/10 for the main runs and 70/30 at condenser inlets, pump suctions and other high-velocity features. Where sand or entrained air is expected, the case for 70/30 strengthens, since both accelerate erosion of the protective film.
Seawater Performance and Limits
Copper nickel 70/30 tolerates higher seawater velocity than 90/10 and resists erosion corrosion better, particularly where sand or entrained air is present. It shares the family's weaknesses: attack in stagnant polluted water containing sulphides, sensitivity to ammonia, and poor performance in strongly oxidising conditions. It is not a sour service material for hydrocarbon systems. State your velocity, water quality and temperature in the RFQ; requirements are confirmed at quotation.
Pricing Copper Nickel 70/30 Pipe and Tube
- Raw material surcharges for the alloying elements in this grade
- Seamless or welded construction
- Diameter, wall thickness and cut lengths
- Required finish and cleanliness
- Testing, certification level and witness requirements
- Quantity and availability
- Incoterm and port of discharge
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 and local flow velocities, certification, inspection, destination port and required date.
Mill Certificates and Verification
Copper Nickel 70/30 is supplied 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. The certificate should record chemistry, heat treatment, tensile properties and any additional testing ordered. Positive material identification is worth specifying wherever several stainless grades share a fabrication shop. See the MTC and EN 10204 certification guide.
Storage and Contamination Control
Lead time is confirmed at quotation. Material is capped and, where specified, wrapped to protect the surface. Iron contamination is the main storage risk: carbon steel tools, slings and airborne grinding dust all leave particles that rust and can trigger pitting, so segregation on the Gulf laydown yard matters as much as the original grade choice.
Fittings and Related Grades
- Copper nickel 90/10 pipes and tubes
- Copper nickel 95/5 pipes and tubes
- Titanium grade 2 pipes and tubes
Copper nickel 70/30 is used across desalination and water treatment, power generation condensers and marine and offshore systems.
Copper Nickel 70/30 FAQ
When should 70/30 be used instead of 90/10?
Where flow velocity is higher, particularly at pump suctions, bends and condenser inlets, or where sand or entrained air accelerates erosion.
How much stronger is 70/30?
Minimum tensile strength 372 MPa against 262 MPa, and minimum yield 138 MPa against 90 MPa.
Can both alloys be used in one system?
Yes. Many seawater systems use 90/10 for the main runs with 70/30 at high-velocity features.
Does 70/30 resist biofouling?
Yes, like other copper nickel alloys, through copper ions at the surface.
What is the EN equivalent?
CuNi30Mn1Fe, material CW354H.
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 70/30 Pipes and Tubes (UNS C71500)
Send the OD, wall, length and quantity, with the local velocities at bends and inlets rather than the average alone. Every enquiry is checked before the offer is prepared, so the grade matches where the erosion risk actually is.