Coating Reference Handbook - Hempel

HEMPEL
CORROSION CATEGORIES R 20
ISO 12944 Section 2
The standard ISO 12944 has introduced a characterisation system for the
corrosivity of environments. You may find many environments characterised by
a simple abbreviation as follows:
CATEGORIES FOR ATMOSPHERIC EXPOSURE
Low carbon Examples of typical environments
Corrosivity steel in a temperate climate (informative only)
Category thickness
loss
micron
Exterior Interior
C1 =< 1.3 - Heated buildings with
very low clean atmospheres, e.g.
offices, shops, schools,
hotels
C2 >1.3 to 25 Atmospheres with low Unheated buildings
low level of pollution. where condensation
Mostly rural areas may occur, e.g. depots
sports halls
C3 >25 to 50 Urban and industrial Production rooms
medium atmospheres, with high humidity and
moderate sulphur some air pollution, e.g.
dioxyde pollution. food-processing plants,
Coastal areas with low laundries, breweries,
salinity. dairies.
C4 >50 to 80 Industrial areas and Chemical plants,
high coastal areas with swimming pools,
moderate salinity. coastal ship- and
boatyards.
C5-I >80 to 200 Industrial areas with Buildings or areas
very high high humidity and with almost permanent
(industrial) aggressive atmosphere condensation and with
high pollution.
C5-M >80 to 200 Coastal and offshore Buildings or areas
very high areas with high with almost permanent
(marine) salinity. condensation and with
high pollution.
CATEGORIES FOR WATER AND SOIL
Category Environment Examples of environments
and structures
Im1 Fresh water River installations, hydro-electric
power plants
Im2 Sea or brackish water Harbour areas with structures
like sluice gates, locks, jetties;
Off-shore structures.
Im3 Soil Buried tanks, steel piles
steel pipes.
For exact details of this extensive ISO-standard, including 8 sections
comprising all aspects of corrosion protection by coatings, please consult
the standard itself.
INSPR20 ed1 VALIDITY SUBJECT TO CONFIRMATION 15/08/00 EMi