What depth is considered severe corrosion?

• A. Over 0.010 inch
• B. Under 0.010 inch
• C. Exactly 0.010 inch
• D. 0.020 inch

Answer: (A)

Severe corrosion is defined by how deep the metal loss from corrosion has penetrated. If that depth is greater than 0.010 inch, it’s considered severe because the remaining material thickness may no longer meet structural limits and the area typically requires more than cleaning—often repair or replacement per the approved data. To assess it, you clean the area, locate the deepest pit, and measure from the original surface to that depth with a micrometer or similar tool. Any depth over 0.010 inch falls into the severe category, whereas depths at or below the threshold are not classified as severe. A specific depth like 0.020 inch is also severe, but stating the general criterion as “more than 0.010 inch” covers all deeper cases.