Accelerated corrosion of a boiler chimney: causes and preventive steps

Abstract

Heavy corrosion attack was observed on the SS 304 liner used on the upper part of a mild steel chimney stack in a boiler. The corrosion had taken place due to the condensation of acidic flue gases. The corrosion damage in the liner material was even higher at locations, where a ladder was attached to the chimney body. Heavy thinning of the mild steel chimney body at such locations had also taken place from the inside, i.e., the inner surface exposed to the flue gas atmosphere. The chemical analysis of the corrosion deposits and condensates confirmed the presence of highly acidic environment (pH 2) consisting of mostly sulfate ions. Remedial measures to prevent future occurrence of the problem are also addressed.