Vibration Analysis of P - 29 Motor-Pump Assemblies Insight Project Date Dec 1 st, 2010 Prepared By Reviewed By Liyana (Jay) Jayathilake, P.Eng Lal Perera M.Sc., P.Eng Customer Contact Customer Order
SUMMARY Vibrations on P - 29 motor-pump assembly was monitored and analyzed. Casing vibrations on motor bearings are marginally high, but the shaft vibrations are low and acceptable. Continue operation of the motor but monitor the vibrations. If the vibrations increase withdraw and send it for overhaul Note: Only one proximity probe on pump inboard bearing is functioning. Correct at the earliest opportunity. Refer recommendations in the section 3.1.
CONTENTS Vibration Analysis Report Page 1. Introduction 1 2. Vibration Guideline Limits 1 3. Findings, Comments and Recommendations 2-3
1. INTRODUCTION The pump P-29 tripped due to high vibrations on outboard bearing as indicated on monitor panel installed on the unit. Plant personnel suspected that motor vibrations transmitted through the base and caused the pumped to trip. Insight Engineering Services was requested to analyze machine s vibration and determine the cause. Tests were performed on November 29 th, 2010. ZonicBook multi-channel data acquisition unit and CSI advance two channel analyzer were used to acquire the data. 2.0 VIBRATION GUIDELINE LIMITS 2.1 API 610 - Vibration Guideline Limits for overhung or in between bearing horizontal mounted pumps. Overall Vibration Levels Vibration Peaks at Discrete Frequencies Pump Bearings 0.17 in/sec Peak 0.113 in/sec Peak Motor Bearing 0.10 in/sec Peak 0.10 in/sec Peak 2.2 API 610 - Vibration Guideline Limits for Vertically suspended pumps. Overall Vibration Levels Vibration Peaks at Discrete Frequencies Pump Bearings 0.28 in/sec Peak 0.184 in/sec Peak Motor Bearing 0.28 in/sec Peak 0.184 in/sec Peak 2.3 ISO 10816 Group 3 Vibration Guideline Limits for external drive machines Overall Vibration Velocity mm/sec rms in/sec peak 0.0 2.3 0.0 0.13 mm/sec in/sec 2.3 4.5 0.13 0.25 mm/sec in/sec 4.5 7.1 0.25 0.39 mm/sec in/sec Above 7.1 Above 0.39 mm/sec in/sec Criteria Acceptable levels for a new unit that is set into operations. Continuous operation is acceptable. Periodic monitoring to assess the condition is recommended Acceptable for a limited period of operation. Plan for corrective work Danger, damage could occur at any time. Do not operate the unit. Correct the problem without delay
3.0 TEST RESULTS AND FINDINGS Casing vibrations on the motor were monitored. Highest vibrations showed in the horizontal direction and dominant peaks excited at 1x rpm order and at 120 Hz. Lubricating oil on motor bearings were changed and tests were performed. No significant change was observed and overall vibrations still remained marginal. Overall vibration levels are shown in table 1 and spectrum are shown in Appendix A. Shaft vibrations on the motor and pump remained low and acceptable. The vibrations on the pump base are low and acceptable. See appendix B. Figure 1:- The upper window shows the overall casing vibration levels and the lower window shows the vibration and the spectrum of the motor outboard bearing. (Red curve is horizontal, Blue is Vertical and Green is Axial)
Figure 2:- Upper window shows the overall vibration levels and the lover window shows the vibration spectrum of the motor inboard bearing. ( Red curve is horizontal, Blue curve is vertical and Green curve is axial)
Table 1 - Overall vibration levels of pump P-29 Point Point Descriptions Overall Vibration in/sec MOH Motor Outboard Horizontal 0.123 MOV Motor Outboard Vertical 0.081 MOA Motor Outboard Axial 0.038 MIH Motor Inboard Horizontal 0.123 MIV Motor Inboard Vertical 0.057 MIA Motor Inboard Axial 0.037 PIH Pump Inboard Horizontal 0.123 PIV Pump Inboard Vertical 0.093 PIA Pump Inboard Axial 0.050 POH Pomp Outboard Horizontal 0.136 POV Pump Outboard Vertical 0.069 POA Pump Outboard Axial 0.066 PCH Pump Center Horizontal 0.069 PCV Pump Center Vertical 0.033 Prox-Probe Vibrations mils MOX Motor Outboard X 0.85 MOY Motor Outboard Y 0.65 MIX Motor Inboard X 0.95 MIY Motor Inboard Y 0.95 PIX Pump Inboard X - PIY Pump Inboard Y 1.75 POX Pomp Outboard X 0.50 POY Pump Outboard Y 0.35
3.1 COMMENTS AND RECOMMENDATIONS Casing vibrations on motor bearings are marginal but the shaft vibrations are low. No immediate action required, continue the motor to be in service. If the motor vibrations increase and show an upward trend withdraw the motor from service and send for overhaul. The pump may have tripped due to a sudden spike or faulty signal of the proximity probe. Only one proximity probe is working on the pump outboard bearing. This should be rectified as soon as possible. 4.0 Data Vibration Tables and Spectrum Plots Appendix A Pump Assembly Vibrations and spectrums. Appendix B Pump Base Vibrations and spectrums.