REMAINING CREEP LIFE PREDICTION OF USED GAS TURBINE BLADES

One of the important units in a gas turbine is the turbine blades. Turbine blades are exposed to thermal and centrifugal stress which results a certain deformation and microstructure changes as the usage time increases. In industries, the frequent practice is replacing the turbine blades whenever manufacturers recommended useful life time reach. Manufacturers recommend useful life assuming the plant operates at maximum load. But, the engine operation depends on the load demand and change of inputs. Basically, this way of doing work is very costly and wasting money if the blade could still be used. So, by predicting the remaining creep life, the blade might have longer useful life than the manufacturers’ recommendation. Thus, the aim of this study was to predict the remaining creep life of used gas turbine blades. This was be done by using Stress-Rupture test analysis under certain conditions of stress and temperature. In order to interpret and analyze the result of the study, Larson-Miller parameter and Life Fraction rule were used. The changes in microstructure of the materials were analyzed by using the Field Emission Scanning Electron Microscope (FESEM). The turbine blades were supplied by Malaysia Liquefied Natural Gas (MLNG) Labuan. The result shows that turbine blades suffered from several microstructure changes based on their service life. Other than that, it had been found out that the turbine blades could still be use approximately for more than a year based on its’ operating stress and temperature.