6.5 Weather and Rates of Corrosion

Weather affects the rate of corrosion of metal in both coastal and inland locations. Most chemical reactions, including corrosion, are affected by temperature, humidity, wind speed, and other factors. Higher temperatures and higher humidity increase corrosion rates. Like any weather-driven condition, corrosion rates can vary considerably from year to year.

Short-term measurements of corrosion rates at specific locations can be misleading unless compared to long-term averages for nearby locations because average weather conditions for factors such as rainfall seldom occur. In any given year, measured rainfall can be much higher or lower than the average rainfall.

As a result, the corrosion rate for a given area in an individual year may be significantly higher or lower than the long-term average rate. Because corrosion rates vary, inspections and maintenance should be done at least annually, and preferably more often, to identify connectors and fasteners that need to be replaced. See Section 9.2 for more information on maintenance and replacement.