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API 614 BROCHURE INFO.Full description
Rotating equipmentFull description
DOCUMENT NO: INCIDENCE
TPCL/IMS/MMD/RCM/08
REPORT
TATA POWER
Occurrence Date: 18.07.2011
Time: 05:30 pm
Incidence:
Failure of Voith lube oil oil pump of ID fan#3A Brief description of incident: An alarm ‘LUB OIL PRESSURE LOW’ of Voith coupling of ID fan#3A was observed in control room on18.07.11 in “B” Shift. The same was inspected and abnormal sound from Voith coupling was reported. Initial observation indicated that the abnormal sound was being generated from Voith Coupling but later on it was observed that the lube oil pressure was also showing zero. Immediate Action taken: Since the oil pressure was showing zero, the control room was immediately informed to stop the ID fan#3A.Immediate information was conveyed to TISCO (LDC) through Operation Department seeking their clearance for Fan shut-down on 18.07.11.Man power was arranged near the Fan for constant monitoring of the sound and Fan running condition till Fan shut-down was taken. Corrective Action taken: The Fan Shut down was taken on 18.07.11 for inspection and rectification after necessary clearences. After thorough inspection the following points were noted: Observations: • • • • •
The voith coupling was too hot The voith top cover was opened for inspection Oil was observed to be too hot. The runner assembly of voith coupling was was hot A play was observed observed in lube oil pump shaft
The runner of the Voith coupling along with new lube oil pump was replaced and finally the fan was made available on 19.07.2011
Analysis: •
•
•
•
As lube oil pressure pressure was showing zero zero and an abnormal sound sound was also coming from the pump so there could be an abnormality in the voith pump itself. As the chockage of suction line and discharge discharge line of the the pump also could lead lead to zero discharge pressure. The same was inspected the suction and discharge line was found clean. The pressure gauge was also checked it was found ok. Now the lube oil pump was dismantled .The key and the key way of the pump spur gear was found damaged. All other parts like the plain bearings of DE and NDE side, gears were found in good condition.
The failure of key and key way led to relative motion between pump shaft and pump spur gear which resulted in zero discharge pressure of the pump. The close observation of key way showed the mark of welding mark. It implied that the key way was repaired in past. Because of poor bonding between the parent material and welding material it got failure at the welded position leading to failure of key way also.
In this condition, if the fan was kept in continuous running, there was a possibility of failure of the bearing of lube oil pump and main bearings of Voith coupling. This could have u ltimately led to seizure of the voith coupling itself.
Corrective Measures : The runner and pump of the voith coupling were replaced. Fresh oil was topped up to the mark. A correction in the motor alignment was carried out. After box up, trial of the fan was conducted and found satisfactory. • • • •
Preventive Measures : To avoid repetition of the failure the following steps are taken : 1.
Lub oil pumps to be thoroughly inspected during annual overhauling as well as opportunity maintenance.
Recommendation:1. In case of similar failure keyway to be put in opposite side of the failed keyway. 2. OEM to be communicated about such failure and ask for any modification.
Shift Personnel present during the occurrence : Shift in charge (Reporter) MMD Engineer Vikrant Singh
MMD Technician
Biswajit Dey
Suresh Kumar
Personnel present during job work out: MMD in charge MMD Engineer S.S.Chatterjee
Loss of Incentive due to ID Fan Outage Annual Fixed Charges (proposed in ARR) Loss in availability due to drop in pottential AFC allocated to regulated capacity
Rs Crs
94.71
%
0.09
Rs Crs
47.355
Loss in Incentive due to the pottential loss
Rs Crs
0.0254
Rs Lakhs
2.54
Assumptions: 1)AFC proposed to JSERC has been considered 2) Calculated only for regulated capacity 3) Assumed that Unit 3 will atleast maintain a year end availability of 85%
