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SOLUTIONS: Copper and Copper Alloys Nickel bronzes (Cunifer) “Cunifer 10” (copper nickel) and “Cunifer 30” (cupro nickel) are supplementary alloys to Yorcalbro. These alloys are corrosion resistant – the higher the nickel content, the higher the resistance. Strength and hardness also increase in relation to nickel content.

port where the seawater is polluted by sulphides, the pipes may become coated with sulphide-containing sludge which can stimulate corrosion over a prolonged period even when the vessel moves to cleaner waters. In such cases the use of “Cunifer 10” or “Cunifer 30” piping is recom­

CUNIFER 10 (Copper nickel)

CUNIFER 30 (Cupro nickel)

(Alloy)

Ni 10%, Fe 2% Cu 87%, Mn 1%

Ni 30%, Fe 0.7% Cu 68.5%, Mn 0.8%

530–580 390–500 310–390

360–400

Tensile strength N/mm2 – Hard (untreated) – Heat treated – Annealed

630–700

2.08

Elongation %

– Hard (untreated)  10– 15   5– 10 – Heat treated   20– 35 – Annealed  40– 55  40– 55 – Hardness HB – Hard (untreated) 155–184

165–204

– Heat treated   97–126 – Annealed  78– 97  87–107 Specific weight

8.9

8.9

– Outside coefficient per °CV

0.000016

0.000015

These alloys which have special properties and are widely used on vessels in river and canal traffic, on lakes, or on vessels which regularly call at ports where the water is heavily polluted or contains, sand or sludge. They have excellent resistance against wear by erosion, corrosion and abrasion. When it is envisaged that the piping in a cooling system will be exposed to sulphide polluted seawater, material with good resistance against water of this type should be chosen. Industrial discharge may contain sulphides, and even during a short stay in a

mended. The use of 70/30 piping was previously limited due to high cost. However, the recommendation for the use of these pipes over the entire dimension range is based on the fact that 70/30 pipes have a considerably higher resistance to pitting corrosion than 90/10 pipes. Thermal power plants all over the world use 70/30 pipes to handle polluted cooling water. The same recommendation applies to vessels which are regularly subjected to polluted water in cooling systems. Brazing: AG60 and AG60/45 FLUX. TIG welding: ICUNI 30-239. Wire welding: ICUNI-W-239.

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