Advancements in Gas Turbine Vane Repair

Abstract

The evolution of industrial gas turbines has been a driving factor in the advancement of repair techniques for industrial gas turbine components. Turbine vane segments (also known as stationary blades, non-rotational airfoils, or nozzles) are among the many components that have been a focus for repair development. Due to increasing engine efficiencies, the design of gas turbine vane segments continues to become progressively more complex. Neoteric vanes are cast of highly developed superalloys, have complex cooling designs, and are coated with the latest generation coating systems which utilize advanced oxidation resistant bondcoatings combined with thermal barrier coatings. While advanced technologies enable these vanes to operate at the extreme hot gas path running temperatures of today’s engines, they also significantly increase the level of technology required to successfully repair them. The ability to repair these components is essential to minimize the operators’ life cycle cost of the gas turbine. Recoating, reestablishing of critical cooling, dimensional restoration, along with surface and structural restoration using high strength weld and braze techniques are essential for these vanes. Conventional and advanced repair techniques are key elements in the continuing evolution of industrial gas turbine component repair development. This paper will focus on a variety of Siemens’ technical competencies applied during the restoration of service run vane segments for the turbine section of a gas turbine. These repair competencies and technology/service options include: • Dimensional restoration techniques utilizing hot and cold straightening; • Utilization of refurbished blade rings for completed roll-in/roll-out exchanges; • Coupon repair techniques; • Braze restoration of cracks; • Laser etching; • Strain tolerant coatings; • Future technologies under development.