Automated abrasive water jet pin cutting system — Mark II

After a long operation time, steam turbine blades need to be removed, inspected and/or replaced. Numerous steam turbine fleets have blades that are attached to the rotor discs by the means of pins. At the time being, the pins are removed using a hydraulic jack. Roughly 10% of the pins of steam turbine rotor need to be drilled out due to strains and deformation of the pin. The drilling process is very time consuming and implicates a high risk of damaging the disc. From 2008 to 2010 ALSTOM has developed a system for steam turbine pin removal using the abrasive water jet cutting technology with respect to the geometrical and process requirements. In 2010 this system was redesigned and a Mark II built, tested and used under real conditions in special service applications during the last two years. Promising results have been achieved regarding process speed and process quality during these applications.