Maintenance Methode Evaluation of Casing Alignement Using Laser Measurement Technique: A Case Study of Gas Turbine Generator 100 MW Class

In the asset management system, the management of maintenance activities includes both preventive and corrective maintenance management methodologies. It is defined as maintenance specifications and schedules, procedures for maintenance execution and missed maintenance, inspection measurements and results. During the Major Inspection Overhaul the casing alignment activity on rotating equipment, especially the gas turbine generator (GTG) is a form of maintenance activity that is grouped into life cycle delivery. This is a follow-up on asset performance and health monitoring. This activity involves aligning or leveling the turbine casing in the X and Y axes so that the GTG unit can operate reliably. During the life cycle of an asset from the construction stage to operation, there will be a change in the structural characteristics of the GTG foundation resulting in a change in the position of the turbine casing, both the internal casing and the external casing. Changes in casing position and casing deformation can result in misalignment and vibration when the unit is operating. This work aims to provide an understanding of the effectiveness of using laser alignment on the GTG casing. The method used is taking points on all compressor casing, compressor discharge casing (CDC), inner barrel, turbine casing, turbine shrouds, inlet casing, exhaust casing, and all pedestal bearings. In case alignment work is generally done by 2 methods, top on and top off. Top On is done by attaching the upper casing to the lower casing, while the top-off is done without installing the upper casing, both methods are carried out without the rotor being attached to the turbine casing. Based on the case study of the GTG 100 MW class has been proven to be able to speed up measurement time compared to the piano wire method for 1 days and get accurate results where the measurement results can reach 0.001mm in carrying out internal alignment on GTG. This method benefits unit owners with reduced maintenance time and increased unit performance.

Keywords: Casing alignment, Piano wire, Laser alignment, Procedures for maintenance execution.

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