How to prevent corrosion problems in centrifugal pumps?
Corrosion inside a centrifugal pump can affect wet surfaces or a small portion of its internal components, and is generally or highly localized. Usually, pump failures are caused by highly localized and affected components. Therefore, finding a solution that can reduce the impact of corrosion is very important.
Let's take a look at different methods to reduce corrosion below! This can not only help you save millions of dollars, but also extend the lifespan of the pump.
1. Material selection
When solving corrosion problems, material selection should be considered first. This can not only address corrosion issues, but also select the optimal material based on the operating conditions of the centrifugal pump to reduce the degradation rate.
Cast iron has relatively low corrosion resistance, which rapidly reduces the performance of the pump. So, pump manufacturers use stainless steel to avoid corrosion.
Please note that the correct material selection is ultimately the responsibility of the user. Only users can control the liquid being pumped relative to concentration, temperature, etc. The responsibility of the pump manufacturer is to provide the selected materials under physically good conditions and to provide the correct chemical composition while meeting the specified hydraulic requirements. In practice, reliable pump suppliers will provide guidance based on their previous experience with similar services.
We suggest carefully considering the selection of materials, which is one of the most effective ways to improve the anti-corrosion performance of pumps.
The sources of information that can be referenced for material selection include:
(1) First-hand factory experience;
(2) Similar applications in other locations;
(3) Corrosion diagram of Hydraulic Research Institute;
(4) Recommended diagram for mechanical seals;
(5) Experience of pump manufacturers;
(6) Appropriate literature, texts, and similar references.
Usually, there is no available data that would specifically meet the conditions, especially when solutions containing several chemicals of different concentrations are being pumped. When the temperature increases by 10 ℃, the corrosion rate can be doubled.
The presence of dissolved air or other oxidants in the liquid may individually accelerate the corrosion rate, otherwise it is considered an acceptable situation. Under certain conditions, trace amounts involving only a few million parts of an element can be sufficient to cause severe corrosion attacks, and the basic composition of a solution typically does not cause severe corrosion reactions.
Similarly, pitting corrosion that occurs during extended downward cycles can be suppressed as much as possible by emptying and flushing the pump upon entering the "downward" cycle
