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Corrosion Copper Pipes

Copper pipes are often used in newer properties. Until some time ago, copper pipes were considered the ultimate among water pipe materials. In the meantime, multilayer composite pipes or the cheaper variation normal plastic pipes have been installed.

Compared to the even older iron pipes, copper pipes have the advantage of having much smoother inner surfaces. As a result, they offer the lime considerably less attacking surface. This smooth surface results in significantly less incrustation in copper tubes.

Ideally, a thin film of lime will form on the inside of the pipe to protect the copper from corrosion. But if there is too much calcium carbonate in the water, copper pipes can also become clogged with lime over time.

Copper Pipes

Corrosion

If, on the other hand, there is too little lime in the water, i.e. the water is considered soft. Then a protective layer can only form to a much lesser extent. This can also lead to corrosion in copper pipes. If the water stay in the pipe for a longer period of time, the oxygen begins to gas out. This might be another reason for corrosion.

Copper oxide (CuO or more rarely Cu2O) is formed and the copper reacts with the oxygen dissolved in the water. If large quantities of copper oxide have formed in the pipes, this often leads to a slightly greenish discoloration of the water. Any limescale deposits, e.g. on aerators, may also have the greenish shimmer typical of copper.

Metal impurities in the water can lead to contact corrosion. This happens, for example, when rust particles from the public water network get into the water pipe. The rust particles and the copper form a galvanic element, which in the worst case leads to pitting. Nothing else then a leak in the pipe.
This form of galvanic corrosion can only be mitigated by Merus, since the galvanic element is usually too strong in the case of copper and iron (0.8V potential difference). The phenomenon of contact corrosion can be observed very well in copper gutters. If an iron nail lies in the gutter and it is damp, the nail eats through the copper and the gutter becomes leaky.
Same is true for pipes. The corrosion might lead in the end to so called pinhole leaks in the piping network. If there are pinhole leaks one have to do plumbing and repair the pipe. Either replace the piece of pipe with the leak, or close the leak. If one has access to the leak a plumber can solder the pipe. Shrink hoses are some times an option as well.

Results

Merus Ring on copper pipes

The Merus Ring is able to decompose existing lime. And second to slow down or completely stop corrosion due to soft or stagnant water. You can recognize it by that, after some time, the green discolorations disappear and the water flows again completely clear.
One can assume when a greensih looking water is clean again, the corrosion in the copper pipe is as well far less or stopped.
If the pipe dont corrode anymore, there will from no pinhole leaks either.
We anyhow recommend to use a particle filter at the entrance of the water in the piping network. If there are no metall particles the risk of galvanic corrosion is minimized. The cost of a filter is far less compared to the damage done when a pipe corrode.

One might think that the statements on lime and corrosion contradict each other. A thin layer of lime is desirable in copper pipes to prevent corrosion. Merus degrades the lime, thus theoretically contributing to a higher risk of corrosion. However, it is the case that a Merus ring in the same time is effective against corrosion and thus protects the copper.

Copper is also often used in heat exchangers because of its very good thermal conductivity. In particular, smaller, so-called brazed plate heat exchangers are often made entirely of copper. Such small exchangers are also frequently found in district heating systems.

If such heat exchangers are filled with water, Merus dissolves the lime into the water. There are results and figures under „Volume in heat exchanger„.

 

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