Magnetite forming in iron pipes

Magnetite, with chemical formula: Fe3O4, is an iron ore found in igneous, metamorphic rocks. It belongs in the same group of iron ore as the hematite or the maghemite. Magnetite is a chemical compound of iron and oxygen and therefore an oxide. Magnetite is physically rather stable, as it is an octahedral crystal. It can also be magnetized and was known has lodestone. We call magnetite also saturated iron oxide.

Black magnetite, with a high specific gravity, is used in water filter processes. In so called heavy concrete, it is used to increase the density of the concrete and make it this way stronger.

For Merus it is relevant in terms of magnetite forming in water systems, made of iron or steel.

Merus is treating water systems. One of our key solutions we offer, we are solving corrosion problems. By stopping the corrosion on a metal surface, we remove in the same process the rust. This process is linked to forming of magnetite in the end.

How magnetite forms?

After installing the Merus Ring, the existing corrosion will be stopped or strongly reduced. The rust is automatically removed downstream the point of installation. The solved rust is carried with the liquid. Once the rust is removed from e.g. a pipe, a layer of magnetite is automatically forming on the inner surface. This can be easily seen, as this magnetite is a black layer on the metallic surface.
This phenomenon of magnetite forming in water or steam pipes, is know from water systems having an oxygen-deficient. In other words, if there is not enough oxygen in the water to finalize the oxidation, then magnetite (Fe3O4) forms, instead of the more common Fe2O3 rust.

In this case Fe3O4 is very useful. Its crystal habits make the pipe inert against new corrosion, the black layer is almost like a passivation. This black layer is so stable not even Microbiologically Induced Corrosion – MIC has a chance to harm the steel surface.
Once the magnetite is exposed to enough oxygen, the black layer disappears after a short time and forms normal rust again. This happens usually when a pipe is without water and open to the atmosphere. If the water comes again and the system is still equipped with the Merus Ring, the corrosion will be removed again and the black layer forms once more in short time.

Visual Inspection of the Merus Performance

Thanks to its strong dark colour, magnetite is easily visible to our customers. Thus, the results of the Merus Water Treatment can be seen directly on the pipe. If you are interested in further information concerning the performance monitoring please visit click here.

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