Classification of the degree of corrosion in metal materials
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Metal materials (steel, with carbon steel as the focus) are characterized by their corrosion rate in different corrosive environments, expressed in mm/a. Various sources use different criteria to classify the severity of corrosion; for example, mild corrosion (>0.05 mm/a), moderate corrosion (0.05–0.5 mm/a), severe corrosion (>0.5 mm/a), or complete corrosion resistance (>0.01 mm/a), fair corrosion resistance (0.01–0.2 mm/a), and no corrosion resistance (>0.2 mm/a). Is there any standard that defines and specifies the above levels of corrosion severity?
It is understood that there are no standards for corrosion; only relevant literature exists. Different sources classify the corrosion rates of various metal materials in different ways, but the general benchmarks remain consistent. In devices used in practical applications, it is difficult to accurately calculate their corrosion rate, which makes it hard to establish uniform standards.
For some manufacturers that supply materials, they define their own criteria for corrosion rate and severity. Since these definitions vary from company to company, it’s important to understand why they use such definitions before looking at the relevant tables… This will help in understanding the data more clearly. Additionally, and most importantly, it’s advisable to find information from other manufacturers for comparison, or to check data from books, in order to ensure the accuracy of the information
NACE RP0775-05 specifies that corrosion coupons prepared, installed, and tested in oilfield operations indicate severe corrosion when the rate is greater than 0.25 mm/y； 0.13-0.25, indicates high corrosion ； 0.025-0.12, moderate corrosion ； Less than 0.12 indicates low corrosion.