How To Prevent Water Pump Corrosion?

Oct 27, 2021

(1) Wear corrosion: refers to a kind of erosion corrosion of metal surface by high-speed fluid. Fluid erosion is different from the abrasion caused by solid particles in the medium. The water pump will be worn during operation, so we should try to use materials with good wear resistance to reduce its wear and corrosion. Of course, different materials have different wear and corrosion resistance.

 (2) Electrochemical corrosion: electrochemical corrosion refers to the electrochemical process in which the contact surface of dissimilar metals forms a battery due to the difference of electrode potential between metals, so as to corrode the anode metal. The measures to prevent electrochemical corrosion are as follows: first, sacrificial anode is used to protect the cathode metal; Second, the flow channel of the pump shall be made of the same metal material.

(3) Intergranular corrosion: intergranular corrosion is a kind of local corrosion, which mainly refers to the precipitation of chromium carbide between stainless steel grains. Intergranular corrosion is very corrosive to stainless steel. The measures to prevent intergranular corrosion are: annealing stainless steel or ultra-low carbon stainless steel (C < 0.03%).

(4) Uniform corrosion: uniform corrosion refers to uniform chemical corrosion of the whole metal surface when corrosive liquid contacts the metal surface. This is not only a common type of corrosion, but also a less harmful type of corrosion. The measures to prevent uniform corrosion are to adopt appropriate materials (including non-metallic materials) and consider sufficient corrosion allowance in the design of water pump.

 (5) Crevice corrosion: crevice corrosion is a kind of local corrosion, which refers to the corrosion caused by the local destruction of metal passive film due to the decrease of oxygen content and / or pH value in the crevice after the crevice is filled with corrosive liquid. The use of metals with high Cr and M0 content can prevent or reduce the occurrence of crevice corrosion.

(6) Pitting corrosion: pitting corrosion is a kind of local corrosion. Due to the local damage of metal passive film, hemispherical pits are rapidly formed in a local area of metal surface, which is called pitting corrosion. The pitting corrosion is mainly caused by CL 1. M0 containing steel (usually 2.5% Mo) can be used to prevent pitting corrosion, and the M0 content should increase with the increase of Cl content and temperature.

(7) Stress corrosion: stress corrosion refers to a kind of local corrosion caused by the joint action of stress and corrosive environment. The measure to prevent stress corrosion is to use austenitic Cr Ni steel with high Ni content (Ni; > 25% - 30%).

(8) Cavitation corrosion: the corrosion caused by cavitation of the pump is called cavitation corrosion. The practical and simple method to prevent cavitation corrosion is to prevent cavitation. However, water pump cavitation can not be prevented. Cavitation will occur more or less during water pump operation. For those water pumps that often produce cavitation corrosion, cavitation resistant materials can be used to increase their cavitation resistance.