Angular Misalignment
Possible Symptoms
- High axial vibration at 1x, 2x and 3x (2x may be higher than 1x)
- Phase relationship across coupling typically ~180°
- 1x radial vibration trends up over time due to “unraveling” of disc pack
General appearance
- Fracture near bolt hole
- Fretting at fracture location
- Fracture may occur through bolt hole
Typical causes
- Thermal movement
- Foundation setting
- Pipe strain
- Loose anchor bolt/ studs
- Poor initial alignment
Corrective actions
- Check parallel offset AND face runout on each side as the angularity (offset + face runout) may be different between ends
- Review thermal growth values of equipment (if applicable) and perform hot alignment
