Why choose cupronickel over stainless steel for a marine heat exchanger?

For two reasons: notably higher thermal conductivity than stainless steel, which improves heat-transfer efficiency, and natural resistance to biological fouling that reduces maintenance. In return, mechanical strength and high-velocity erosion-corrosion resistance are lower than stainless steel.

What's the difference between 90/10 and 70/30?

70/30, richer in nickel, better resists high flow velocities and hot seawater, but costs more. 90/10 suits most moderate-velocity uses.

Is admiralty brass still used?

Less than before: cupronickels have largely replaced it for their better resistance to stress corrosion and dezincification. It remains present on some existing installations — send us your requirement to check availability.

Are these alloys available in welded tube?

No, generally: the cupronickels in this family are offered as seamless tube through our partners. An important difference from stainless steel to check ahead of a specification.

GRADE FAMILY

Copper alloys for heat exchangers

Cupronickel 90/10 and 70/30 are the reference for marine condensers and heat exchangers: good thermal conductivity, natural resistance to biological fouling, and solid seawater performance with no PREN to calculate. 70/30, richer in nickel, steps up in resistance for high flow velocities and hot seawater.

What is a copper alloy for piping?

A copper alloy for industrial piping is here, most often, a cupronickel: a copper-based alloy with 10 to 30% nickel depending on the grade, chosen for its thermal conductivity, its seawater resistance and its natural tendency to limit surface biofouling.

When to choose this family — and when not to?

Choose it for condensers and heat exchangers in seawater or marine cooling circuits, where thermal conductivity and fouling resistance matter as much as corrosion resistance. Avoid it in the presence of ammonia or high-concentration sulphur, which specifically attack copper.

Grades in this family

The grades listed are examples, never a closed catalogue — every grade belongs to one of the nine families, which is what makes this claim reliable.

Examples in the copper alloys for heat exchangers family (familles-nuances.json), EN and PREN filled in from nuances-inox.json when the entry exists — not a closed catalogue
Grade (example)	EN	Indicative PREN
CuNi 90/10	CW352H	does not apply to this family
CuNi 70/30	CW354H	does not apply to this family
Laiton amirauté	—	—
Bronze	—	—

Typical applications for this family: Heat exchangers · Condensers · Sugar refineries · Naval and defence.

My grade isn't listed →

Available forms and dimensions

Seamless tube, fittings, flanges and bars available in 90/10 and 70/30 through our partner mills — no welded tube in this family. Outer diameter from 6 to 168 mm — structured data available for CuNi 90/10 and CuNi 70/30 only. The other grades in this family don't yet have this in our structured reference data: send us your requirement via a quote request.

Applicable standards

ASTM B111
ASME SB111
EN 12451
BS 2871 Part 3
JIS H3300
NF A51-102

Frequently asked questions

Why choose cupronickel over stainless steel for a marine heat exchanger?: For two reasons: notably higher thermal conductivity than stainless steel, which improves heat-transfer efficiency, and natural resistance to biological fouling that reduces maintenance. In return, mechanical strength and high-velocity erosion-corrosion resistance are lower than stainless steel.
What's the difference between 90/10 and 70/30?: 70/30, richer in nickel, better resists high flow velocities and hot seawater, but costs more. 90/10 suits most moderate-velocity uses.
Is admiralty brass still used?: Less than before: cupronickels have largely replaced it for their better resistance to stress corrosion and dezincification. It remains present on some existing installations — send us your requirement to check availability.
Are these alloys available in welded tube?: No, generally: the cupronickels in this family are offered as seamless tube through our partners. An important difference from stainless steel to check ahead of a specification.