Life Assessments Of A Boiler Economiser Unit

An economizer 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 further failures through metallurgical assessment, extreme value pitting assessments, and on-site NDT condition assessment with on-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 recommendations 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 i.e. continue with assessment, full economizer replacement or partial replacement. Selective replacement of a portion of the economizer was recommended.