After a recent major outage, we’re seeing blade tip clearance issues on our steam turbine. The clearances are out of spec in some sections, causing efficiency losses and vibration.
Here’s what we’ve done so far:
Verified rotor alignment.
Checked bearing clearances.
Conducted thermal expansion analysis.
Could this be related to rotor bowing or casing distortion? What steps can we take to restore proper clearances?
Check for rotor sag. We had a similar issue where the rotor sagged during the outage, causing clearance problems. Performing a cold rotor inspection helped us identify the issue.
Look into your casing bolts. We found that uneven bolt tensioning caused casing distortion, leading to clearance issues. Retightening the bolts to spec solved the problem.
Consider adjusting your startup procedures. Rapid temperature changes can cause uneven thermal expansion, affecting clearances. Slowing down the heat-up process may help.