Classification of OCAS outdoor exposure site

In addition to being a test site for long term outdoor exposure for test samples, OCAS has been monitoring the necessary weather conditions in order to classify this outdoor exposure site at OCAS Zelzate according to standard ISO 8565.

Classification of corrosivity is based on weight loss measurements of standard specimens exposed during one year using the outdoor site of OCAS, Zelzate (south/45°).  In order to evaluate the results of the corrosion measurements of the exposed standard specimens, it is necessary to characterize the atmospheric conditions at the test site. For that reason we have been monitoring air temperature (°C), relative humidity (%) and precipitations (mm). Installed filters capture the concentration of SO2 (mg/m².d) and by using the wet candle and filter method we have been measuring the concentration of chloride (mg/m².d).  From this data OCAS classifies total time of wetness (τ), pollution by SO2 (Pd) and pollution by chloride (S).

Since 2014, frequent monitoring has been done. Based on data collection accoding to ISO 8565 (Metals and alloys – Atmospheric corrosion testing – General requirements) and using test procedure ISO 9226, during these past years, we can categorise the OCAS Zelzate exposure site as:

  • C2 for steel,
  • C3 for zinc,
  • C1/C2 for aluminum

Following ISO 9223 and ISO 9225, the climatological corrosivity rate is determined as C3/C4 for this site.

In addtition to our Zelzate site, we also have access to the Endures exposure site at the harbour of Den Helder.


“Our outdoor exposure site complements more advanced electrochemical lab measurements. It allows us to validate our findings during longer term exposure.” 

Lien Van de Voorde, Team leader, Surfaces department, OCAS