LABORATORY SIMULATION ON THE EFFECT OF STRAIGHTENING PROCESS OF PLTU PACITAN UNIT 2 HIP ROTOR

• Main Author: Wijaya, Arya
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/86986
• Institution: Institut Teknologi Bandung

During the Mean Inspection+ (ME+) overhaul of PLTU Pacitan Unit 2, an issue was identified with the HIP turbine rotor, specifically excessive deformation with a maximum TIR of 310 ?m detected through runout testing. This deformation resulted in high vibration levels on bearing 1 and bearing 2, predominantly at the 1x RPM spectrum, exceeding the alarm threshold. To address this issue, the deformation has traditionally been corrected using straightening processes involving two methods: hotspot and peening. These straightening processes successfully reduced the maximum deflection value to 50 ?m and resolved the high vibration issue. However, the hotspot and peening processes left permanent marks on the rotor, necessitating further study to evaluate the impact of these straightening methods on the material properties. The research methodology began with a literature review to identify relevant parameters. Subsequently, laboratory-scale testing was conducted on 30Cr1Mo1V material specimens. The material was observed under three different conditions: untreated, hotspot-treated, and peening-treated. The specimens were evaluated through metallography, SEM-EDS, hardness testing, tensile testing, and residual stress analysis. Two main findings emerged from this investigation. First, there was a significant increase in hardness in the hotspot-treated specimens, rising from 232.2 HV to 383.6 HV. Second, the peening-treated specimens exhibited tensile residual stress of 441 MPa. Both findings have the potential to significantly impact rotor operation in the field. Further treatment of the peening specimens using stress relief annealing at 540°C successfully reduced the residual stress to 112 MPa, simulating actual operating conditions in the field. This approach is expected to mitigate the negative impacts of the straightening process during operation.