Marine and Shipbuilding
C71500 is the most common copper nickel alloy for shipboard seawater systems.
| Ship application | Why C71500 is used | Typical sizes |
|---|---|---|
| Firewater mains | Impact resistance, reliability | 4-8″ SCH 40 |
| Sea chests and intakes | Biofouling prevention | 6-12″ SCH 40 |
| Cooling water to heat exchangers | Corrosion resistance up to 80°C | 2-6″ 13 BWG |
| Propeller shaft liners | Wear resistance in seawater | Custom seamless tube |
| Deck wash systems | No pitting from salt spray | 1-2″ 14 BWG |
Why not stainless? Shipboard piping has many stagnant zones (valves closed for weeks), crevices (flange gaskets), and biofouling. 316L fails in these conditions. C71500 does not.
Power Plants
C71500 is used in circulating water systems and heat exchanger tubes in coastal power plants.
| Power plant application | Why C71500 is used | Typical operating conditions |
|---|---|---|
| Main condenser tubes | Seawater cooling, biofouling resistance | Velocity 2-3 m/s, temp 25-40°C |
| Auxiliary cooling water | Long life without replacement | Intermittent operation |
| Intake screens and piping | Debris and sand resistance | Low velocity, high debris |
| Turbine lube oil coolers | No SCC risk like stainless | Temperature up to 60°C |
Real example: A 500 MW coastal power plant replaced 316L condenser tubes with C71500 after two failures in five years. The C71500 tubes have run for 12 years with no tube leaks.
Desalination Plants
C71500 is widely used in multi-stage flash (MSF) and reverse osmosis (RO) desalination plants.
| Desalination application | Why C71500 is used | Challenging conditions |
|---|---|---|
| Brine heaters (MSF) | High temperature resistance (up to 120°C) | Hot brine, 60-100°C |
| Heat recovery sections | Corrosion resistance in high-chloride brine | Salinity 2x seawater |
| Reject brine lines | Pitting resistance in stagnant zones | Low flow, high solids |
| Evaporator tubes | Long service life between replacements | Temperature cycling |
Why not 316L? Desalination brine has double the chloride of normal seawater. 316L pitts rapidly. C71500 handles it.
Most MSF desalination plants built in the Middle East use C71500 for brine heater tubes. C70600 is sometimes used in lower-temperature stages, but C71500 is required for hot brine.
Offshore Oil and Gas Platforms
C71500 is standard for firewater and cooling systems on offshore platforms.
| Offshore application | Why C71500 is used | Typical sizes |
|---|---|---|
| Firewater ring mains | Impact resistance, no SCC risk | 6-12″ SCH 40 |
| Seawater lift pumps (risers) | Sand and debris tolerance | 8-16″ SCH 80 |
| Cooling water to topside exchangers | Reliable in splash zone | 4-8″ SCH 40 |
| Hydraulic control lines | Small diameter, no pitting | 1/2-1″ 14 BWG |
Real example: North Sea platforms use C71500 for all seawater-wetted piping down to 100+ meters. 316L is not permitted on many platforms due to SCC risk in warm chloride environments.
Chemical and Petrochemical Plants
C71500 is used in cooling water and heat exchanger applications where chlorides are present.
| Chemical plant application | Why C71500 is used | Typical service |
|---|---|---|
| Cooling water heat exchangers | Chloride resistance | Treated or raw seawater |
| Quench water coolers | Good thermal conductivity | 40-80°C range |
| Brine coolers (refrigeration) | No pitting in chlorides | Low temperature |
| Desalter effluent coolers | Hydrocarbon + water service | 30-70°C |
Where C71500 is NOT used in chemical plants:
Ammonia service (any copper alloy fails)
High-velocity clean water (316L is cheaper)
Acidic service (pH below 4)
Smaller Applications for C71500 Copper Nickel Pipe
| Small application | Why C71500 is used | Typical quantity |
|---|---|---|
| Shipboard laboratory cooling lines | Low flow, no pitting | 50-200 ft |
| Fishing vessel seawater systems | Reliable in remote ports | 200-500 ft |
| Private yacht air conditioning cooling | Biofouling prevention | 100-300 ft |
| Marine aquarium water circulation | Non-toxic, no rust | 50-100 ft |
| Desalination units on lifeboats | Long storage without corrosion | 10-50 ft |
FAQ
Q1: Which application uses the most C71500 pipe?
Shipbuilding and offshore platforms. A single large vessel or platform can have 5-20 tons of C71500 pipe in seawater systems. Power plants and LNG terminals are also large-volume users.
Q2: Can I use C70600 instead of C71500 in these applications to save cost?
Yes, but with compromises. C70600 works in power plant condensers and desalination lower-temperature sections. For offshore firewater or ship fire mains, C71500 is required by many specifications because of higher velocity capability.
Q3: Is C71500 used in potable (drinking) water systems on ships?
Yes, it is certified for potable water. Both C71500 and C70600 are approved for drinking water. But it is expensive for that use. Many vessels use C70600 or other copper alloys for potable water.
Q4: Do you have case studies of C71500 pipe in your applications?
Yes, for all applications above. We have supplied to shipyards in Korea, China, and Europe; power plants in the US and Middle East; and LNG terminals in Australia and Qatar. Ask us for project references.
Q5: What is the typical service life of C71500 in a power plant condenser?
20-30 years minimum. Some C71500 condenser tubes from the 1980s are still running. Failure is usually from mechanical damage or debris impact, not corrosion.
Q6: Can C71500 be used in wastewater treatment plants?
Yes, but usually not needed. Wastewater is less corrosive than seawater. 304 or 316 stainless is often sufficient and cheaper. C71500 is over-specified for most wastewater applications.
Q7: Is C71500 used in fish farms or aquaculture?
Yes, for seawater intake and circulation. Copper nickel is naturally antifouling, so it reduces cleaning labor. Some fish farms use C70600 instead to save cost.
Q8: Which standard do most offshore projects require – ASTM, BS, or EN?
ASTM B111 is the most common for offshore globally. Even European offshore projects often accept ASTM. US Gulf of Mexico and Middle East projects almost always specify ASTM.
Q9: Can you provide references from shipyards that use your C71500 pipe?
Yes, on request with customer permission. We have supplied to major shipyards including Hyundai, DSME, and Fincantieri. Contact us for reference letters.
