VIBRATION ANALYSIS REPORTVIBRATION ANALYSIS REPORTVIBRATION ANALYSIS REPORTVIBRATION ANALYSIS REPORT

Date: 16/04/2014

Machinery I.D. No. : FLS No. 331.FN110

Machinery Name : ID Fan

Priority Code : 4(Baseline readings after repairs).

Readings : Readings are in units of velocity (mm/s RMS)

Fault Summary : Fan Rotor Unbalance & Possible misalignment

S/N Meas. Pt.

Measurement Point

Description

Readings

@14/04/14

(910rpm)

Readings

@16/04/14

(920rpm)

1 M1H Motor outboard Horizontal 1.100 0.560

2 M1V Motor outboard Vertical 0.384 0.342

3 M1A Motor Outboard Axial 0.885 1.153

4 M2H Motor Inboard Horizontal 1.103 0.593

5 M2V Motor Inboard Vertical 0.522 0.435

6 M2A Motor Inboard Axial 1.376 6.178

7 F1H Fan Inboard Horizontal 9.836 2.013

8 F1V Fan Inboard Vertical 2.934 1.256

9 F1A Fan Inboard Axial 4.804 7.261

10 F2H Fan Outboard Horizontal 7.207 1.483

11 F2V Fan Outboard Vertical 3.532 0.564

12 F2A Fan Outboard Axial 2.025 6.450

Figure 1 – Vibration Signatures from fan bearing (Horizontal/ axial) showing dominant peak at fan operating

frequency.

Figure 2 – Images of broken support bolt (NDE bearing housing) before corrective action.

Figure 3 – Images of replaced support bolt (NDE bearing housing) after corrective action and a cross-channel phase

measurement set-up.

Observations:

� Vibration data analysis showed dramatic drop in the radial vibration across the entire

machine train after the implementation of corrective actions. However, there exists

an increase in the overall axial vibration at the operating frequency of the fan (920

CPM). This could be attributed to a possible shaft misalignment due to a movement

induced by the looseness (See figure 1). Also, the radial dominance of fan 1X vibration

is due to residual rotor unbalance.

� A cross channel phase analysis between fan bearing housings and baseplates

indicated an in-phase between both members while drive/non-drive bearings(H-V)

showed an out of phase by 90 degrees. This is an indication that the relative

movement (looseness) has been arrested as a result of the tightening of support bolts

and residual unbalance is still existent.

� Broken fan support bolt has been extracted, replaced and others tightened(See figure

2)

Recommendations:

� Check shaft-motor alignment status during any possible stoppage

� In the interim, routine monitoring and trending should continue.

-Michael M. Osagada