EVALUATION METHOD OF GAS TURBINE BLADES COVERING INTEGRITY BY IR CAMERA

Abstract

Key parts of the main equipment in a gas turbine may likely be damaged due to operation under high temperature, high pressure, high-speed rotation, etc. Accordingly, the cost for maintenance increases and the damaged parts may cause generation to stop. The surface of a blade is thermal-sprayed, using powder with main compositions such as Ni , Cr , Al , etc, in order to inhibit hot oxidation. Conventional regular maintenance of the coating layer of a blade is made by FPI (Fluorescent Penetrant Inspection) and MTP (Magnetic Particle Testing). Such methods, however, are complicated and take a long time and also require high cost. In this study, defect diagnostics were tested on the coating layer of an industrial gas turbine blade, using an infrared thermography camera. Since the infrared thermography method can check a temperature distribution by means of non-contact on a wide range of areas, it can advantageously save expense and time as compared to conventional test methods. For the infrared thermography method, however, thermo-load must be applied onto a tested specimen and it is difficult to quantify the measured data. To solve the problems, this paper includes description about producing a specimen of a gas turbine blade (bucket), applying thermo-load onto the produced specimen, photographing thermography images by an infrared thermography camera, analyzing the thermography images, and pre-testing to analyze defects on the coating layer of the gas turbine blade.