For the classification of corrosion, there are two classification methods, one is based on the mechanism of corrosion classification, and the other is based on the causes of corrosion and image classification. According to the mechanism of corrosion, the main points can be divided into electrochemical corrosion and chemical corrosion. The electrochemical corrosion mainly refers to the metal material after contact with the electrolyte solution, the corrosion phenomenon caused by electrode reaction occurs on the surface of this reaction is generally a redox reaction, the main factor is the environment humidity and temperature; chemical corrosion refers to the metal surface and the surrounding medium contact will react more strongly thus, the metal have been damaged, this is the main reason of corrosion induced by high temperature and dry environment. According to the appearance and causes of corrosion, the classification can be divided into, stripping layer corrosion, industrial atmospheric corrosion, high temperature oxidation corrosion and marine atmospheric corrosion, etc..
In the industrial pollution in the environment, the more the sulfide, carbon dioxide and hydroxides and other volatile substances in the air, but also contains some industrial dust, these are prone to corrosion medium. These media in the humid environment, acid gas will form a combination of water inorganic acids, these acids have a strong corrosion performance, so it will cause corrosion. Under the environment of industrial atmosphere, the equipment is caused by electrochemical corrosion and direct chemical corrosion. All the nature of corrosion, in fact, is a metal element in the loss of electrons after the formation of an ion oxidation process. For electrochemical corrosion and industrial atmospheric corrosion is the main difference between the two different environment.
The corrosion of the equipment and related materials, in the selection process of chemical materials, should focus on the corrosion situation, pay attention to the reasonable material, environmental nature, taking into account the full medium temperature and operation pressure and so on, according to the requirements of chemical raw materials. The structure and type of equipment design. The structure should be designed around the characteristics requirements of production operation in chemical equipment and stress, in the design should pay attention to the following aspects: the first is the structure of products should be the production of chemical products and corrosion requirements consistent; the second is to observe the stability and fluency of the equipment, to prevent with corrosion medium pauses, heat load distribution is not uniform, condensation and corrosion products of the vapor accumulation; finally is to pay attention to external force protection, prevent alternating stress and fatigue corrosion.
