An economiser which experienced pitting corrosion during a cleaning accident was subject to recurring corrosion fatigue failures. A condition assessment was undertaken to assess the risk of tirt.her failures through metallurgical assessment, extreme value pitting assessments, and on-site NDT condition assessment withon-site extreme value pitting analysis. This was followed by a fatigue life assessment in accordance with PD6493. Condition assessment work and lifetime prediction progressed from initial failure investigation through to final recommendation in a stepwise process. Each stage of the work was followed by a review of the findings and an economic assessment of the alternative options ie continue with assessment, full economiser
replacement or partial replacement. Selective replacement of a portion of the economiser was recommended.