Integrity assessment of an embrittled steam turbine casing

This work reviews a recent structural integrity assessment carried out on a high-pressure turbine inner casing that had suffered from temper embrittlement. The assessment was carried out to demonstrate that the casing can be safely returned to service based on revised operating conditions with particular emphasis on the control of temperature ramp rates during start-up and shutdown events. A retirement-for-cause philosophy was adopted to take into consideration that some operational flexibility will be required prior to the casing being replaced at the next planned outage.