Types of Corrosion in Centrifugal Pumps and How to Prevent Their Occurrence

09 January 2023

Centrifugal pumps may sound industrial, but they can also be used in domestic applications. By principles, these pumps can transport fluids by converting rotational kinetic energy that comes from an electric motor or an engine into hydrodynamic energy. Hydrodynamic energy helps transfer and pump water, solvents, oils, acids, bases, and other thin liquids in agricultural plants, industrial properties, and domestic areas.

One great thing about most centrifugal pumps today is they are energy efficient. Compared to other pumps, centrifugal pumps are known to consume only a minimal amount of energy, which can lower the utility bills of the users. These pumps can also deliver smooth, pulseless fluid flow. They can even last for a long time without requiring high maintenance work.

Corrosion in Centrifugal Pumps 

The only problem with centrifugal pumps is they can corrode. While some manufacturers have managed to improve their corrosion resistance, many of them can still corrode due to various factors. One of the factors that can lead to pump corrosion is the combination of the fluid’s flow or velocity and the fluid’s corrosive activity. As the fluid flows inside the pump, the protective films of its components may wear off until they get damaged. Most of these things happen around the tube blockage, pump impellers, and in the ends of tube inlets.

Erosion can also force the centrifugal pump components to corrode. Once the passive layers of the centrifugal pumps have been damaged by erosion, their surfaces become active, which quickens the process of corrosion.

Major Forms of Pump Corrosion

Centrifugal pump corrosion may come in three major forms.

1. Uniform Corrosion: It is a form of corrosion wherein the material loss rate on the surface of the pump is uniform and even. Compared to other forms of corrosion, uniform corrosion is said to be the least damaging. It is also easy to pinpoint and evaluate. Most uniform corrosion occurs with pumps made from cast iron. To prevent this form of corrosion, one should opt for pumps made from stainless steel or nickel-based superalloys.

2. Galvanic Corrosion: Galvanic corrosion may not be as common as uniform corrosion, but it is said to be more harmful than the said form of corrosion. This corrosion happens whenever various base metal surfaces are used in creating a pump. And if an electrolytic medium like acid or alkali is present on the pump, it can charge the said medium and cause corrosion to the said metals. Galvanic corrosion can be prevented by using a pump with similar metals.

3. Pitting Corrosion; Pitting corrosion is a form of corrosion wherein the protective layer or coating of the pump has been damaged. Once damaged, the underlying metal will be exposed to the medium, which can deteriorate its surface in the long run. To prevent pitting corrosion from happening, one should maximise a pump with metals protected with proper coatings. Alloys with high nickel content can usually deter corrosion of the pumps.

Centrifugal pump corrosion can be prevented by choosing the right material, utilising protective coating, and carrying out regular maintenance. If you need some help with centrifugal pumps and their coatings, you must contact us at Fluid Sealing.

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