Corrosion selection for racking is usually reduced to a coating name and a number of salt-spray hours. Neither is a service-life prediction.
IEC 62817 sets a floor of ISO 9223 class C2 for the corrosion environment considered. A floor is a minimum test condition, not a recommended specification for coastal, floating or agrivoltaic sites.
This entry is the evergreen reference that our technical and trade articles link to.
Why this entry exists
Class to coating matrix
ISO 9223 classes C1 through CX describe atmospheric corrosivity. We map them to common coating systems and the environments where each is typically specified, while noting that national and project specifications vary.
The framework
The non-conversion rule
Microns of coating and hours in an ISO 9227 salt-spray cabinet are accelerated-test parameters. They cannot be divided into years of service without a validated correlation for the specific environment.
Where the floor is not enough
Coastal, floating and agrivoltaic installations add chlorides, permanent humidity or chemical exposure. A spec that stops at C2 should be flagged in a design review.
Data box
| Field | Value as reported |
|---|---|
| Standard link | IEC 62817 corrosion requirement, ISO 9223 C2 minimum |
| Classes | C1 to CX |
| Coating systems | Zn-Al-Mg, hot-dip galvanising, duplex systems |
| Test standard | ISO 9227 salt spray |
| Rule | Test hours are not service years |
All figures above are quoted with the unit and reference period used by the primary source. They are reproduced here for reference, not independently re-measured.
How to use it in a tender or a brief: verification note
C2 is the standard's lower bound, not a general recommendation. Coastal, floating and agrivoltaic scenarios require higher classes; we never present the floor as a universal selection.
What to watch next
Field exposure data that correlates accelerated test duration with real service life for Zn-Al-Mg coatings.
Primary sources
- ISO 9223 (corrosivity classification)
- ISO 9227 (salt spray tests)
- IEC 62817:2014+AMD1:2017+AMD2:2026 CSV
Researched and written by the solarrack.wiki editorial desk. Every figure in this article carries a source and a verification note; where a claim could not be confirmed against a primary document, it is labelled as such. Corrections: [email protected]
