Alu/Brass vs Cu/Ni

In the previous two blog posts, we covered the Copper-Nickel and Aluminum-Brass coolers individually. In those, we went into detail about the benefits and concerns of each material type. This post will compare the two material types and determine which situation is better than the other. We will compare them on material, fouling protection, purchase price, maintenance and operational costs.

Materials:

When you put the two types of boxcoolers next to each other, several things immediately stand out, such as the colour, thickness of the tubes, and different materials. The Copper-Nickel boxcoolers are not coated, so the bare pipe material is clearly visible. Copper naturally turns green over time as it reacts with (sea)water – a chemical reaction. The green colour is simply the patina’s natural shade that forms over the copper surface; the patina protects the copper from deterioration and creates a light bluish-green facade. This green layer will protect our Copper-Nickel boxcoolers from fouling marine growth.

The Coated Aluminum-Brass boxcooler is brown-orange due to the marine coating that protects the cooler from corrosion and stray currents. This coating protects the tubes well, allowing the cooler to resist chemicals and obstacles floating in the marine environment.

Also noteworthy is that the Copper-Nickel variant is equipped with a white Teflon support baffle that holds the tubes together and protects them from vibrations. In the case of the Aluminum-Brass box cooler, it is painted brown-orange by the coating just like the pipe bundles.

The tubes are also of different thicknesses. The Copper-Nickel variant is 10mm thick compared to the Aluminum-Brass variant, which is 8mm thick.

The Copper-Nickel boxcooler has a more robust (and environmental friendly) design to withstand harsh marine environments because of the thicker tubes.

With the thinner tubed on the Aluminum-Brass variant, the coating is creating a solid cooling unit.

Fouling protection:

The Copper-Nickel uncoated variant has natural anti-fouling capabilities. This alloy does not require a protective coating or ICAF (Impressed Current Anti-Fouling) system due to its inherent corrosion resistance to seawater and natural anti-fouling capabilities. To protect the uncoated boxcoolers against potential stray current and corrosion, a WEKA Guard™ and WEKA Protector™ system are applied.

The coated Aluminum-Brass variant has no natural anti-fouling capabilities and needs an additive system to protect the box cooler. Two types of systems can protect the boxcoolers from fouling: an ICAF (Impressed Current Anti-Fouling) and a USAF (Ultra Sonic Anti-Fouling).

ICAF systems use copper anodes connected to a compact control unit. An impressed current is sent to the anodes causing them to release a small number of copper ions to the water flowing through the seawater tubes or sea chests. This creates an environment in which microorganisms cannot attach themselves.

Ultrasonic systems produce multiple bursts of ultrasonic energy in a range of targeted pulse frequencies. These pulses are transmitted through the material to which the transducer is attached.

The ultrasound produces a pattern of increasing and decreasing pressure on the surface of the material. Microscopic bubbles are created during the negative cycle and are imploded during the positive cycle. This microscopic agitation has a cleansing effect that destroys surface algae.

Disrupting this first link in the food chain keeps the surface clean and makes it a much less inviting habitat for larger organisms that feed on the algae. The microscopic movement of water also prevents barnacle and mussel larvae from embedding on the surface.

The two differ most in terms of impact on the environment. Namely, ICAF is toxic to marine life and therefore bad for the environment. After five (5) years (depending on the intensity of use), the copper sacrificial anode must be replaced, a capital-intensive investment.

An ultrasonic system is non-toxic to the environment and is maintenance-free. After installation, it only needs to be checked that all the LED indicator lights are still on. This means that the transducers are doing their job correctly.

Purchase price:

The raw materials in the Copper-Nickel variant are of high quality. Also, as mentioned earlier, the tubes are thicker, which increases the weight of the cooler. The price per kilogram of Copper-Nickel tubes compared to Aliminium-Brass is almost one and a half times more expensive, which means that the price of a Copper-Nickel box cooler is higher than the Aluminum-Brass variant. The Teflon support plate is also more expensive than then its aluminum counterpart. The Aluminum-Brass variant costs for the protective marine coating are also taken into account. The real difference is made when purchasing fouling protection.

For the Copper-Nickel variant, the cost for fouling protection is only the Weka Guard and Weka Protector. For coated aluminum-brass boxcoolers, an ICAF or USAF system must be purchased, which can suddenly add up to high costs. It is often forgotten to take this into account when selecting the boxcoolers. However, an ICAF system, depending on the position of the boxcoolers in the sea chest, can easily cost 5000 Euros per boxcooler. Also, a USAF system is not cheap eighter and costs about 1750 Euros per boxcooler.

Maintenance/operational costs:

As already described in the purchase cost, the big difference is in the way of fouling protection. This has a significant impact on the maintenance and operating costs of the boxcooler. An ICAF bar must be replaced every five (5) years (depending on the intensity of use). This requires the vessel to go into the dry dock. If USAF is used, they do not need to be replaced or maintained. Using a Copper-Nickel box cooler, the Weka Protector should be replaced every five (5) years as the battery will run out. Further maintenance on these coolers is not necessary.

For the coated Aluminium-Brass boxcoolers, the coating should also be checked during dry-docking. If there is any fouling on the coating, it should be removed using a high-pressure hose. The coating should then be inspected for damage from hosing. This may otherwise lead to leaks at a later stage. If the coating is damaged, the entire boxcooler should be cleaned in an acid bath and then recoated.

Ideally designed for:

The Aluminum-Brass coated box cooler is ideal for use in conditions where water is contaminated or during dredging operations. The protective coating ensures that the tubes are not damaged and continue to do their work well.

The Copper-Nickel version is ideal for use in areas with a lot of marine life. For example, fishing boats can ideally use the Copper-Nickel version so that the fish are not poisoned by loose coating or copper ions from the ICAF system. Most of the floating fish farms in Scandinavia use our Copper-Nickel box coolers to cool their installations.

Points of attention and benefits:

To briefly summarize the comparison, the Points of attention and benefits will be listed.

Aluminium-Brass

Benefits:

• The coating has a protective effect, making it resistant to contaminated environments
• The cheapest option at purchase
• Applicable in any vessel

Points of attention:

• The additional system required for fouling protection
• Takes more space in the vessel
• Higher operational costs
• Environmentally harmful

Copper-Nickel

Benefits:

• Environmental friendly
• Low maintenance
• Long lifespan
• Natural anti-fouling capabilities

Points of attention:

• More expensive
• Vulnerable to polluted water as long as the ship is not sailing
• Must be installed fully insulated

Would you like to discuss the best suitable cooling solution for your vessel or installation? Please do not hesitate to request more information or discuss the possibilities with our Weka sales engineers. Tell us your cooling challenges, and we are ready to help you!

If you have any questions regarding (un)coated boxcoolers, please contact our sales department by email: sales@wekamarine.com or by phone: +31(0)180 516 588.