Site Corrosivity Estimator
Four questions, one indicative ISO 9223 category
- C1Very low
- C2Low
- C3Medium
- C4High
- C5Very high
- CXExtreme
How this works
Method
The estimate starts from distance to the sea and then applies up to three adjustments, one step each. The result is kept between C2 and C5.
| Factor | Effect |
|---|---|
| Distance under 500 m / 0.5–5 km / over 5 km | Starting point C5 / C4 / C3 |
| Humid climate (annual mean above 80% RH) | +1 |
| Dry climate (below 60% RH) and over 5 km from the sea | −1 |
| Heavy industry, port or refinery nearby | +1 |
| Urban or light industrial air, when the site is at C3 | +1 |
| Sheltered installation (roofed, screened or indoors) | −1 |
Limits
The estimator does not measure deposition, so local effects — prevailing wind direction, cooling-tower drift, nearby wastewater plants — can move a real site up or down. Use it to decide whether protection is needed and which category to design for, then confirm with the coating selector or with us.
FAQ
How accurate is the estimate?
It is indicative. ISO 9223 categories are properly determined from measured chloride and sulphur dioxide deposition, time of wetness, or metal coupons exposed on site for a year.
Why is CX never returned?
CX covers extreme cases such as offshore platforms and direct wave spray. Treat those sites as CX directly rather than estimating them.
Tell us the equipment, the site and the destination port. We reply within 24 hours.