What Does Rust Rating Scale Mean?
A rust rating scale is used to determine how much oxidation a metal object's surface has undergone. The scale is comprised of a series of pictures that are compared with the actually base material being evaluated. There are several standard rust rating scales available.
Corrosionpedia Explains Rust Rating Scale
A rust rating scale is a tool commonly used to determine the amount of rust on an iron-based alloy.
There are different types of rust rating scales, but all of them include pictures resembling a base material with varying amounts of rust. These pictures are compared to the actual base material being evaluated. The picture that looks the most similar to the base material in question is selected as the corresponding picture. Each picture is assigned a value that is typically the percentage of the surface area covered in rust. This value is then applied to the base material in question.
Rust rating scales are a great way to take subjectivity out of the equation when evaluating corrosion. Without pictures to match with the base material, corrosion inspectors may have wildly different opinions on the severity of the rusting. The pictures help inspectors come to a more unanimous consensus, which is necessary when determining the steps to be taken to deal with the corrosion.