Regarding the corrosiveness of substances

The corrosion rating is determined based on the category of the medium, as well as factors such as environmental humidity and the amount of exposure, and is classified into four levels: high, medium, low, and none. Conceptually, it can be understood as follows: under severe corrosion conditions, the corrosion rate of materials is high; therefore, protective measures that provide surface isolation are necessary to prevent direct contact between the corrosive medium and the components ； Under these conditions, it is advisable to use other materials with lower corrosivity if possible. Under moderate corrosion conditions, the material experiences some corrosion; in such cases, increasing the mass of the component itself or using simple surface protection measures can be employed. Under conditions of mild corrosion, the material corrodes slowly, but certain measures still need to be taken ； Generally, improving one’s own quality is sufficient. Under non-corrosive conditions, material corrosion is very slow or there are no noticeable signs of corrosion; therefore, the components do not require the protective measures specified in these standards.