Environmental Classifications and ISO 12944
When it comes to protecting steel from corrrosion, one of our key standards we work to is ISO 12944. This international standard helps define how different environments affect the rate of corrosion and guides us on what level of surface preparation and coating protection is needed. For VariBlast, understanding these environmental classifications is a vital part of doing the job right, because the conditions around a structure determine how we prepare and protect it.
ISO 12944 categorises environments by how aggressive they are to steel, from C1 (very low corrosivity) to C5 (very high corrosivity), which is split into C5I for industrial and C5M for marine conditions. Each category represents the kind of atmosphere the surface will live in – for example, C3 may be an exterior surface near a road or urban area, whereas C4 may be an industrial plant or chemical facility with constant moisture and pollution. These classifications help us gauge how much protection a surface will need, from the level of blasting and cleaning to the choice of coating system and environmental controls during application.
Above is a table with the correlation between how durable you want your coating system to be with the next expected major maintenance date linked accordingly. While these durability ranges don’t guarantee that coating will last exactly that long, they act as a guide for planning. The harsher the environment and longer the expected durability, the more critical the surface preparation becomes. For example, a C5M environment with a High Durability system demands extremely thorough cleaning, precise control of humidity and temperature during coating and careful inspection throughout.
Understanding both the corrosivity category and durability range is central to how we plan and execute our work. At VariBlast, we ensure that every surface we prepare is ready to perform in its real-world environment. ISO 12944 provides us the framework to ensure every coating system we work on achieves its intended lifespan and performance, providing long-lasting value for our clients.