Failure of the Crude-oil Tank induced by two independent Corrosion Processes

摘要

Corrosion processes are frequent reasons of failure of materials in many applications. Results of failure analysis of the crude-oil tank after more than 30 years of service are summarized in this work. The failure was caused by two different and independent corrosion processes -corrosion in crude oil inside the tank and corrosion from concrete base under the tank. Both corrosion processes usually occur equally over the whole surface. In this case, however, both the corrosion processes occurred with distinctly higher corrosion rate in basic material alongside of heat affected zone of weld joint as well. The crack with length about 420 mm was the final result of these processes. The effect of low-cycle fatigue from filling and draining of crude oil is usually significant and was discussed as well.