Assessment of defects in flue-gas ducts

Technical arbitration panel – leading the OEM team

Cross-section of a boilerIssues arose between the OEM and the utility with regard to materials choice and design detail on the ‘Lobster-back’ section of flue-gas ducts on six 660 MW boilers. Extensive brittle cracking had occurred in the ‘Corten’ steel sheeting of the ducts, with a potential for collapse of the lobster-back.

The problem was attributed by the operator to poor materials choice, by the manufacturer to periodic cold water ingress from the fire-fighting system.

After initial discussions, a technical arbitration panel was convened; this was composed of representatives of both parties and an independent observer. Mr Brear was asked to lead the OEM team.

Agreement was obtained on realistic materials properties, thermal and mechanical loadings, also on failure modes and consequences. A single fracture path was identified that could lead to collapse and a supplementary support system was proposed to eliminate this risk.

Once the optimal technical solution was identified and agreed, litigation was avoided.

Plant Integrity