Environmental screening and relevant accelerated tests for products in an outdoor ground environment

Corrosion is the dominant failure mode of products in underground water pits. The failure mechanism was studied to determine the dominant variables. The major variables, which dictate galvanic and pitting corrosion, are pH, temperature and concentration of the various species in the solution. A field screening procedure was used to determine the concentration of the anions, pH and temperature in different pits. These data show that there are wide ranges of pit severity as indicated by the pH and the total anion concentrations. The two variables of the pit solution viz. pH and the total anion concentration, could be used to characterize a pit environment and determine the material reliability. The field data were used to design relevant accelerated test using the pit characteristics viz. anion concentration and temperature as the accelerating variables. The product application and its reliability requirements determined the time for the accelerated test. In this study we have shown how to characterize a pit environment, design the relevant accelerated test for product reliability and use these data for the best selection of materials, based on low cost and high reliability. This, in turn, will lead to optimum and cost-effective materials used in product design.