Decision help for corrosion classes
The corrosion class indicates the extent to which metal surfaces need to be protected against corrosion by impurity. The impact of the corrosion depends on the atmospherical circumstances of the environment where the object is being/will be used. Salt and humidity in the air, polluted atmosphere and impurities have an effect on the formation of corrosion. Atmospherical corrosion is divided up into the corrosion classes C1 to CX according to ISO 9223. For each class, a minimal and maximal corrosion speed has been determined. The corrosion class applies to both indoor and outdoor use of a metal. Aside from the corrosion classes, there are also four immersion classes for construction used underground or underwater.
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very low corrosivity > indoors dry air and clean indoor climate |
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low corrosivity > indoors and outdoors unheated buildings and national dry areas |
PAINT SYSTEMS STEEL C1/C2 |
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average corrosivity > indoors and outdoors |
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HIGH CORROSIVITY > indoors and outdoors |
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very high corrosivity > outdoors |
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Extreme corrosiviTY > OUTDOORS |
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FRESH WATER |
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SALT AND BRACKISH WATER |
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underGROUND |
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SALT AND BRACKISH WATER |
paint systems immersion |
VERY LOW CORROSIVITY > INDOORS
DRY AIR AND CLEAN INDOOR CLIMATE
PAINT SYSTEMS STEEL C1/C2
LOW CORROSIVITY > INDOORS AND OUTDOORS
UNHEATED BUILDINGS AND NATIONAL DRY AREAS
PAINT SYSTEMS STEEL C1/C2
AVERAGE CORROSIVITY > INDOORS AND OUTDOORS
PRODUCTION SPACES WITH HIGH HUMIDITY CITIES AND LIGHT INDUSTRIAL ENVIRONMENTS WITH MODERATE POLLUTION
PAINT SYSTEMS STEEL C3
HIGH CORROSIVITY > INDOORS AND OUTDOORS
SPACES WITH A VERY HIGH HUMIDITY LIKE SWIMMING POOLS
LIGHT INDUSTRIAL ENVIRONMENTS WITH POLLUTION, NOT NEAR THE COAST
PAINT SYSTEMS STEEL C4
PAINT SYSTEMS GALVANIZED STEEL C4
VERY HIGH CORROSIVITY > OUTDOORS
COASTAL AREAS AND AREAS WITH HEAVY INDUSTRY
A LOT OF POLLUTION AND HIGH HUMIDITY
PAINT SYSTEMS STEEL C5
PAINT SYSTEMS GALVANIZED STEEL C5
EXTREME CORROSIVITY > OUTDOORS
MARINE AND OFFSHORE, VERY AGGRESSIVE ATMOSPHERE
EXTREME HUMIDITY AND POLLUTION OF THE ENVIRONMENT
PAINT SYSTEMS STEEL CX
FRESH WATER
RIVERS, WATER POWER PLANTS
PAINT SYSTEMS IMMERSION
SALT AND BRACKISH WATER
WITHOUT CATHODIC PROTECTION
HARBORS AND LOCKS
PAINT SYSTEMS IMMERSION
UNDERGROUND
DAM WALLS, PIPES AND TANKS IN THE GROUND
PAINT SYSTEMS IMMERSION
SALT AND BRACKISH WATER
WITH CATHODIC PROTECTION
HARBORS AND LOCKS
PAINT SYSTEMS IMMERSION
MAINTENANCE PAINT SYSTEMS PAINT SYSTEMS FOR SHIPS NORSOK PAINT SYSTEMS
DurABILITY
ISO 12944 also describes the lifespan of a paint system. This is the time that it takes till the steel parts need a first big maintenance job. This standard durability is expressed in 4 ranges:
- Low durability (L): up to 7 years
- Medium durability (M): 7 to 15 years
- High durability (H): 15 to 25 years
- Very high durability (VH): more than 25 years