Case Study Failure of Boiler Feed Water Pump-A

CASE STUDY Equipment & Location: Boiler Feed Water Pump # A Dates of Checking’s: 20th, 25th January & 3rd February 2006 Instruments used: Vibration Data Collector/Analyser, Model Easy-Viber Abstract of Case: All of a sudden Seizure of the Pump and Tripping of Unit due to Over Current, created panic in

the mind of Operational Staff. Earlier recorded Vibration Levels did not indicate any abnormal thing in the Motor and Pump Unit. Inspection of the Pump Rotor revealed that two bolts had entered in the Pump Casing and one of those had stuck in between the Impeller locking the rotor, which had seizure of the rotor.

Equipment Specifications: Pump - Boiler Feed Water Pump # A, Make Flowserve, Model ECPJ 25-200, Driver

Electric Motor, Discharge Press 49.61 bar, Max Condition Flow Rate 75.6 m3/Hour, Suction Min/Max Press 2.35/7.013 bar, Head at Rated Capacity 507.3 m, Seal Type Mechanical, Seal Make Flowserve, Seal Model 5A (U) 4X, Diameter of Suction Line 8 inch, Diameter of Discharge Line 4 inch, Head Max 610.6 m, Speed 2,950 rpm, Impellers Diameter 236 mm, Impellers Material 12% Chrome. Coupling Flexible Type.

Vibration Data: The following readings of the Vibration Levels were available in the recorded Data Base.

Actual Date as per

Calendar Point No. & Direction

Velocity mm/sec

rms

BC Value Displacement Microns pk-

pk

Acceleration G

pk 20th Jan 2006 1-Vertical 0.2375 0.08 20th Jan 2006 1-Horizontal 0.6678 0.06 20th Jan 2006 1-Axial 0.3320 0.04 20th Jan 2006 2-Vertical 0.3201 0.03 20th Jan 2006 2-Horizontal 0.6420 0.03 20th Jan 2006 2-Axial 0.3206 0.04 20th Jan 2006 3-Vertical 1.175 0.20

20th Jan 2006 3-Horizontal 1.486 0.16 20th Jan 2006 3-Axial 0.4333 0.28 20th Jan 2006 4-Vertical 1.537 0.58 20th Jan 2006 4-Horizontal 1.112 0.48 20th Jan 2006 4-Axial 0.4278 0.36 25th Jan 2006 2-Horizontal 0.08 0.07154625th Jan 2006 2-Axial 0.3426 0.04 0.7983 0.093649

Vibration Analysis: All of a sudden Seizure of the Pump and Tripping of Unit due to Over Current, created panic in

the mind of Operational Staff. While checking the earlier recorded Vibration Levels, which did not indicate any abnormal thing in the Motor and Pump Unit. It was decided for dismantling of the Pump Assembly for the Internal Inspection of the Pump Rotor.

Actions/Observations: There was no indication of any abnormality form the earlier recorded vibrations. Hence, the

motor was decoupled for doing free run check-up, which was found satisfactory confirming the problem with the pump rotor. The coupling was found in good satisfactory condition. Finally, a decision was taken to dismantle the pump. The mechanical seals also were found in the good condition. Observed that after complete stripping of the pump assembly, revealed that two bolts had entered in the Pump Casing and one of those had stuck in between the Impeller locking the rotor, which had caused seizure of the rotor.

Conclusion: Seizure of the Pump Rotor could be indicated and prevented by the Motor Over Current Trip

System by avoiding further damages to Pump Impeller, Coupling and Motor due to the Over Load Effects. The available Vibration Records could not reveal any abnormality within the Unit. Ultimately, Inspection of Pump Rotor could reveal the exact cause of Seizure/Locking of the rotor. Hence, all the Planned and Systematic Activities carried out can help in resolving the problems by avoiding further Catastrophic Damages to the Machines without any Unscheduled Shutdowns and Production Losses thereof.

SPECTRA REPORT (Dated: 20th Jan. 2006)



















SPECTRA REPORT (Dated: 25th Jan. 2006) Date: 2005/11/05 16:08, Overall = 0.071546 g RMS, BC = 0.08, Shaft Speed =2,970.0 RPM, Bearing =NDH 8513



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Case Study Failure of Boiler Feed Water Pump-A