If you’re sourcing materials for marine, energy, or chemical processing systems, you’ve probably worked with copper nickel alloys before. But when it comes down to choosing between 90/10 and 70/30, the decision can have real consequences — from corrosion resistance to cost and long-term durability.

At PM International, we help procurement teams, engineers, and project managers make the right call based on how these alloys perform in the field. Let’s break it down.

The Basics: What Are 90/10 and 70/30 Copper Nickel Alloys?

Both are copper-nickel alloys known for their excellent corrosion resistance, particularly in saltwater and other aggressive environments. Here’s what sets them apart chemically:

• 90/10 Copper Nickel (UNS C70600)
  
  • 90% copper, 10% nickel
    
  • Small amounts of iron and manganese improve corrosion resistance
    
  • Widely used in marine piping and HVAC systems
• 70/30 Copper Nickel (UNS C71500)
  
  • 70% copper, 30% nickel
    
  • Higher strength and better resistance to high-velocity seawater erosion
    
  • Often used in condensers, heat exchangers, and offshore platforms
    

Comparison Chart: Key Differences That Matter

Property	90/10 Copper Nickel	70/30 Copper Nickel
Nickel Content	10%	30%
Corrosion Resistance	Excellent	Superior
Strength	Good	Higher
Erosion Resistance	Moderate	Excellent
Cost	Lower	Higher
Pipe Pressure Rating	Up to ~300 PSI	Often exceeds 600 PSI
Weldability	Excellent	Excellent
Availability	Widely available	More specialized

When to Use 90/10

• Ideal for general seawater piping, fire mains, HVAC systems, and water distribution
  
• Great choice when fluid velocity is low to moderate
  
• Cost-effective for large-scale installations like shipbuilding or cooling systems

Best Fit For:

• Shipyards
  
• Marine engine rooms
  
• Pulp & paper water systems
  
• Chemical process water loops
  

When to Use 70/30

• Designed for high-velocity seawater and aggressive fluids
  
• Offers greater mechanical strength and erosion resistance
  
• Perfect for high-performance systems that demand longer lifespans under stress
  

Best Fit For:

• Offshore platforms and risers
  
• Power plant condensers
  
• Desalination facilities
  
• High-pressure cooling systems
  

Real-World Example

A U.S.-based shipyard recently upgraded to 70/30 copper nickel for its cooling system retrofit across several high-speed vessels. With flow rates exceeding 3.5 m/s, the team needed extra protection against erosion-corrosion. PM International helped spec out and deliver ASTM B466-compliant pipe cut to length — all on a tight turnaround.

Common Questions We Hear from Buyers

“Is 70/30 always better?”
Not necessarily. Unless your system handles high-velocity flow or you need added strength, 90/10 often performs just as well and is more cost-effective.

“Can I mix both alloys in the same system?”
While technically possible, we recommend using a consistent alloy in each system or zone to reduce galvanic corrosion risk.

“What’s the cost difference?”
Pricing fluctuates, but 70/30 can run 15–30% higher than 90/10, which adds up quickly on large orders.

Why Medium and Large Teams Work With PM International

At PM International, we stock both 90/10 and 70/30 copper nickel in:

• Pipe and tubing
  
• Fittings and flanges
  
• Valves and custom-engineered products
  

We work closely with engineering and procurement teams across the marine, power, chemical, and mining sectors to meet project specs, ensure compliance, and move quickly when timelines are tight.

Let’s Find the Right Alloy for Your Next Job

Not sure which alloy is right? Our team will help you weigh the technical factors, cost implications, and lead time considerations.

👉 Request a Quote Now or call PM International to speak with a materials expert today.