The Corrosivity Categories

Tue, 13 Jun 2023
The Corrosivity Categories

ISO 12944 is a globally recognised standard that provides guidelines on the protection of assets from corrosion. It covers the protective paint systems designed for application to abrasive blasted steel, hot-dipped galvanized steel, and thermally sprayed zinc steel.

The classification of the environment is given in this table:

Corrosivity Category

Application Area – Outdoors

Application Area – Indoors

C1 (Very low)

Not Applicable

Inside heated rooms – offices, commercial buildings, schools, hotels

C2 (Low)

Low pollution, mostly rural areas

Unheated buildings where condensation may occur – storage, facilities, sport centres

C3 (Medium)

Urban and industrial areas, moderate pollution, coastal regions with low salt concentration

High humidity rooms with some air pollution – breweries, dairies, food production facilities

C4 (High)

Industrial areas, coastal regions with moderate salt concentration

Chemical plants, swimming pool, boat houses above sea water

C5 – I (Very high)

Industrial areas with high humidity and aggressive atmospheres

Building and areas with ever present condensation and heavy pollution

C5 – M (Maritime)

Coastal and offshore regions with high salt concentration

Buildings and areas with ever present condensation and heavy pollution


The durability categories of corrosion protection are as follow:

Low

Medium

High

Very High

Up to 7 years

7-15 years

15-25 years

More than 25 years


To find out more information, please contact Exnovo’s team of experts to discuss the best surface protection for your transformer needs.

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