Evaluation prior to protective application (explanation to numbers related to given grade). "Rust & Scale (2Fe203) substrate specification settings" main purpose is to simplify ballast tank reporting and tank status, making recommendations.

10.Grade
XXXL
Extreme substrate build up in multiple scale layers.
Removal: Major detachment by use of mechanical / electrolytic impact.
9. Grade
XXL
Excessive substrate build up in multiple scale layers.
Removal: Major detachment by use of mechanical / electrolytic impact.
8. Grade
XL
Extensive substrate build up in multiple scale layers.
Removal: Major detachment by use of mechanical / electrolytic impact.
Scale layer detachment by use of highly penetrative liquid treatment.
7. Grade
L
Significant substrate build up in multiple scale layers.
Removal: Scale layer detachment by use of highly penetrative and temporary steel protective treatment. Application by spray / floatation.
6. Grade
M
Dense substrate build up in multiple scale layers.
Removal: Scale layer detachment by use of highly penetrative and temporary steel protective treatment. Application by spray / floatation.
5. Grade
MS
Highly dense substrate build up in multiple scale layers.
Removal: Scale layer detachment by use of highly penetrative and temporary protective treatment. Application by spray / floatation.
4. Grade
S
Strongly dense substrate build up in multiple scale layers.
Removal: Scale layer detachment by use of highly penetrative and temporary protective treatment. Application by spray / floatation.
3. Grade
XS
Super dense scale substrate build up, layers not easily recognized.
Removal: Scale layer detachment by use of highly penetrative and temporary protective treatment. Application by spray / floatation.
2. Grade
XXS
Super firm substrate build up, measures made by instrumentation.
Removal: Scale layer detachment by use of highly penetrative and temporary protective treatment. Application by spray / floatation.
1. Grade
XXXS
Scale free surface on sound steel, which stays temporary protected.