In recent years, orders for new land-based gas turbines have skyrocketed, as the planning, construction and commissioning of new power plants based on combined-cycle technology advances at an unprecedented pace. It is estimated that 65–70% of these new equipment orders is for high-efficiency, advanced “F”, “G” or “H” class machines. The W501F/FC/FD gas turbine, an “F” class machine currently rated at 186.5 MW (simple cycle basis), has entered service in significant numbers. It is therefore of prime interest to owners/operators of this gas turbine to have sound component refurbishment capabilities available to support maintenance requirements. Processes to refurbish the Row 1 turbine blade, arguably the highest “frequency of replacement” component in the combustion and hot sections of the turbine, were recently developed. Procedures developed include removal of brazed tip plates, coating removal, rejuvenation heat treatment, full tip replacement utilizing electron beam (EB) and automated micro-plasma transferred arc (PTA), joining methods, proprietary platform crack repair and re-coating.
This paper describes repair procedure development and implementation for each stage of the process, and documents the metallurgical and mechanical characteristics of the repaired regions of the component.