IN-PLANT ELECTROCHEMICAL MEASUREMENTS ON AUSTENITIC STAINLESS STEEL EQUIPMENT OPERATED AT ELEVATED TEMPERATURES

摘要

A report is given of our experience with electrochemical potentiodynamic reactivation (EPR) measurements conducted in industrial installations operating at elevated temperatures. The sensitization behavior after four to five years' service of austenitic welded pipes working at temperatures within the range of 340-600°C was investigated. In situ measurements were carried out on different 150-460 mm diameter pipes during plant shutdown periods. Welded joints, heat affected zones as well as pipe and flange materials were tested. An on-site measuring cell setup was used. A new testing system has been developed to overcome problems encountered with standard instrumentation. New approaches to EPR measurements are recommended based on the new mobile setup. A comprehensive interpretation of the experimental results is given taking into account the C and Mo contents as well as the stabilization and phase transformation relationships.