Here you can find explanations for corrosivity categories and durability ranges according to the new ISO 12944-5: 2018 standard.
C1 - Very Low:
C2 – Low:
C3 - Medium:
C4 - High:
C5 - Very High:
CX - Extreme:
Low - durability until 7 years
Medium - durability between 7 – 15 years
High - durability between 15 – 25 years
Very High - durability over 25 years
Durability is the expected life of a protective paint system to the first major maintenance painting. The durability range is not a guarantee time. Durability is a technical consideration/planning parameter that can help the owner set up a maintenance programme.
NOTE: When the painting system is designed for durability ranges ‘high’ and ‘very high’ in corrosivity categories C4 or higher and in immersion categories Im1 to Im4, the preparation grade must be P3.