1.        corrosion inhibitor: Chromate salt as the main component of corrosion inhibitors is commonly used in cooling water system, acid radical ion is a kind of anodic inhibitor (process), when combined with proper cathodic inhibitor, can get satisfactory anticorrosive and economic effect.

2.        Chromate - zinc – polyphosphate: Poly phosphate is used because it is a clean metal surface, can have the corrosion, polyphosphate can partially into orthophosphate, they can also with the larger of colloidal calcium cation, the inhibition of cathodic process.

3.        Chromate - zinc – phosphonate: This method USES sodium phosphonate in place of polyurethane. Similar to the previous method, aminophosphate can also be used in situations where the pH value specified for polyurethane is higher. Amino-methyl-phosphonate can prevent scale, and even a pH of 9 can control calcium salt precipitation.

4.        Chromate - zinc - hydrolyzed polyacrylamide: Due to the dispersive action of polyacrylamide hydrolyzed by cationic copolymer, it can prevent or inhibit the fouling of scale.

5.        electrochemical protection: Adopt cathodic protection and anodic protection. Cathodic protection is to make the metal surface become cathode by using dc power supply. The anodic protection is to connect the protected heat exchanger to the anode of the external power source, so that the metal surface can generate passivating film, so as to be protected.

Editor’s Note: This is a guest post from Corrosion and Protectionon Wechat , just for sharing