It is with great pleasure we launch this first edition of the Exposure Site Catalogue! Corrosion testing is an important part of corrosion work to estimate, assess, predict, and verify the performance and lifetimes of individual materials, systems, and components. This is an essential input for selection of appropriate corrosion protection systems and, in the end, to achieve sustainable products.

Exposure sites and outdoor exposure have always been a part of atmospheric corrosion research providing the “final answer”, although at the cost of long exposure times. Individual exposure programs such as ISOCORRAG, MICAT and ICP Materials have resulted in collaborative networks of exposure sites. So far, however, there has been no collective effort to put together currently active sites in a comprehensive manner and across programs and nations. The information collected here is possible thanks to the work of all individual site managers listed as contact persons, efforts of members of Working Party 25 (WP25) Atmospheric Corrosion of the European Federation of Corrosion (EFC) and financial support of the EFC. With this Catalogue it is our hope that you can both get a general overview of what is available and be guided if you are looking for a particular environment with certain characteristics.

You will notice that there are several references to information contained in ISO 9223 Corrosion of metals and alloys – Corrosivity of atmospheres – Classification, determination, and estimation. It is recommended to be familiar with this standard, but if you are not. a brief recapitulation of its most important concepts is given in the explanatory notes.

Please do not hesitate to contact us if you are missing anything or have suggestions for improvement!

Corrosivity category or category of corrosivity of atmosphere

This is a standardized rating of the corrosivity of the atmosphere in relation to the one-year corrosion effect. Currently, six different categories are defined, C1 (very low corrosivity), C2 (low), C3 (medium), C4 (high), C5 (very high) and CX (extreme). The categories can be derived in different ways:

• Corrosivity determination based on corrosion rate measurement of standard specimens (recommended), normative based on exposure at test sites such as those in this Catalogue!
• Corrosivity estimation based on environmental information, normative based on dose-response functions including temperature, relative humidity sulphur dioxide level (deposition or concentration#), and chloride deposition.
• Corrosivity estimation based on environmental information, informative based on description of exposure conditions.

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^#In ISO 9223, SO₂ values determined by a deposition method and concentration values are considered equivalent and can be derived from each other by a constant factor with the physical interpretation as a constant deposition velocity. However, the deposition velocity can vary depending on the location, to a great extent depending on the wind speed.

Categories of environment and environmental parameters

Environmental parameters can be classified into different types:

• Climatic parameters including temperature, relative humidity, precipitation amount, etc.
• Gaseous pollutants including SO₂, NO_X, O₃, etc.
• Particulate deposition including chloride deposition and other particles.
• Characteristics of precipitation influenced by long-range and local effects including pH, sulfate,and chloride content, etc.

The environment in general is also frequently characterized into different types such as rural, urban, marine, and industrial. It is however important to note that this description does not indicate the corrosivity category but only the type of the environment (and the types of pollutants that typically dominate in this environment). It is possible to find rural atmospheres having a high corrosivity category and urban sites having a low corrosivity category, even if the opposite is more frequent.

Category of location

This is conventionally defined as typical exposure conditions of a component or structure, for example, exposure in the open air, under shelter, in a closed space, etc. Some of the sites in this Catalogue provide exposure under shelter. It is however important to note that results obtained from one type of shelter are not easily extrapolated to other types of shelters due to the influence of microclimatic factors.