Novel method for determination of pitting susceptibility in aggressive environments at elevated temperature and pressure

Abstract

Electrochemical characterisation techniques have the potential to reduce the number of expensive and time consuming stress corrosion cracking tests during selection of corrosion resistant alloys for oil and gas applications in which pitting is the precursor to cracking. The main challenge for the application of such techniques is the severity of the environmental conditions. Here we report the development of a novel approach to measurement of pitting susceptibility in very aggressive environments at elevated temperature and pressure based on the use of a high surface area rod specimen with the autoclave seal locally cooled to prevent undesirable crevice corrosion that would compromise the measurement. We also demonstrate that measurement of pitting susceptibility using a higher surface area specimen provides a more conservative result than a standard low surface area specimen, which is of practical value where cost constraints preclude statistical analysis of data from multiple repeat tests.