Insufficient tightening of the wheel bolts often results in overhaul at overhaul
Based on the vibration condition of the unit, a shutdown inspection was scheduled. The self-positioning of the No. 4 bearing and its tightness as well as clearance were found to be within normal limits. The low-pressure rotor blades and balance blocks showed no signs of loosening, and the No. 4 shaft vibration probe was functioning properly. However, the short-axis coupling bolts between the low-profile coupling were found to be unevenly tightened. Most of the bolts could be re-tightened, but several had been tightened by approximately 30 degrees, which indicated improper torque application.
After adjusting the tightening force of the bolts, the abnormal vibration of the No. 4 shaft disappeared during the cranking process. However, when the unit speed reached 3000r/min, the vertical vibration of the No. 4 bearing measured 102µm, while the No. 5 shaft vibration reached 234µm. Due to the severe exceedance of the No. 4 bearing vibration, which affected the No. 5 shaft vibration, it was decided to perform on-site dynamic balancing. After re-installing the low-pressure rotor and the low-rise coupling, the vibration at each bearing was below 50µm at 3000r/min. Once the unit was connected to the grid and under load, all shaft vibrations remained below 76µm, achieving the best vibration performance since the unit was commissioned.
Another issue was identified with the exciter’s wheel bolt tightening force or the shaft misalignment. Insufficient tightening of the wheel bolts often led to excessive sway at the No. 7 journal during static checks. However, as the unit rotated, the bolt tightening force changed, causing abnormal vibration in the No. 7 shaft. During subsequent inspections, the sway at the No. 7 journal had altered, even exceeding the acceptable limits. This highlighted the importance of consistent and proper bolt tightening throughout the entire system to ensure stable operation and prevent unexpected vibration issues.
Square Music Dry Spray Fountain
Our company is mainly engaged in the design, production and construction of various waterscape fountains. The company has contracted to build various types of fountains at home and abroad, and years of design and construction have accumulated rich experience and abundant human and material resources for us.There are various kinds of dry sprays, with lights, water curtains and music interwoven and widely used.
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Wuxi Jinshanghua Environmental Equipment Co., Ltd , https://www.jshfountain.com