BOILER FEED WATER PUMPS PERFORMANCE LOSS AMR MOHAMED GAD RASGAS DR.NICHOLAS WHITE RASGAS 29 TH INTERNATIONAL PUMP USERS SYMPOSIUM HOUSTON SEPT.30 TH -OCTOBER 3 RD
Presenter Amr Mohamed Gad Senior Machinery Engineer with RasGas company since 2007 13 years of experience in maintenance, retrofits, and upgrades of Gas Turbines, Compressors and Pumps in natural gas facilities. Previous publications at 6 major worldwide conferences 1 / Boiler Feed Water Pumps Performance Loss
Index RGX2 Steam Condensate System Problem Summary Troubleshooting History Unit 92-P261A Failure Performance Deterioration RCFA-Unit 92-P261A Operational Risk Mitigation Recommendations Results Lessons Learned 2 / Boiler Feed Water Pumps Performance Loss
RGX2 Steam Condensate System Steam condensate system set up at RGX2: Total of x6 Boiler Feed Water Pumps (x4 steam turbine driven pumps and x2 motor driven pumps). Operating philosophy N+2: x4 in service and x2 Stand by operation. x6 No. BFW 3 / Boiler Feed Water Pumps Performance Loss
RGX2 Steam Condensate System Pump specifications: Rated capacity 750 M3/hr Rated power 1.7 MW Differential head 680m Horizontally split casing 4 stage with double inlet impeller 4 / Boiler Feed Water Pumps Performance Loss
RGX2 Steam Condensate System New pump before installation Old pump at skid in RGX2 5 / Boiler Feed Water Pumps Performance Loss
Problem Summary One pump experienced high thrust bearing temperature alarm after 16 months of operation The thrust bearing was replaced twice during the following 6 months without identifying the root cause System operation indicated low pump performance During the 25 months of operation, thrust bearing temperature again reached high alarm level and pump was found seized upon inspection 6 / Boiler Feed Water Pumps Performance Loss
Troubleshooting History Historical Records: Unit 92-P261A historical events shown on a timeline pump s thrust bearing temperature increase due to bearing degradation over one year alarm level reached ( 85 deg C ) Plot-0 120 100 80 60 40 20 0 10/6/2009 8:20:59.518 AM 372.00 days 10/13/2010 8:20:59.518 AM 92P261A PMP NDE BRG TEMP 92P261A PMP NDE BRG TEMP 92P261B PMP NDE BRG TEMP 92P261B PMP NDE BRG TEMP 92P261A PMP NDE BRG TEMP 92P261A PMP NDE BRG TEMP 92P261B PMP NDE BRG TEMP 92P261B PMP NDE BRG TEMP OIL TO PMP & TURB 92P261A WB FR 92P261ABCD WB FR 92P261ABCD 92TI6864AA.PV 32.137 92TI6864AB.PV 28.376 92TI6864BA.PV 65.055 92TI6864BB.PV 58.462 92TI6865AA.PV 32.43 92TI6865AB.PV 29.695 92TI6865BA.PV 74.042 92TI6865BB.PV 75.849 92PI6802A.PV 7.4481E-02 92PI6517.PV 61.984 92PI6518.PV 61.994 7 / Boiler Feed Water Pumps Performance Loss
Troubleshooting History Unit 92-P261A -Vibration readings: Pump D.E radial vibration Pump N.D.E radial vibration Turbine D.E & N.D.E Plot-0 28 24 19 14 9 11.624 10.842 18.608 25.592 8.1319 8.1319 6.2027 8.9133 7.3748 Pump D.E/N.D.E VAH&VAHH is 50/70 Mm PK-PK 11.624 11.233 21.319 26.349 8.1319 7.7411 5.0305 8.9133 7.3748 \\RTIS67\92VI6808AA.P 12.015 UM PP \\RTIS67\92VI6808AB.P 11.233 UM PP \\RTIS67\92VI6809AA.P 20.928 UM PP \\RTIS67\92VI6809AB.P 25.958 UM PP \\RTIS67\92VI6810AA.P 8.1319 UM PP \\RTIS67\92VI6810AB.P 8.1319 UM PP \\RTIS67\92VI6810BA.P 6.2027 UM PP \\RTIS67\92VI6811AA.P 8.9133 UM PP \\RTIS67\92VI6811AB.P 7.7411 UM PP radial vibration 4 2/1/2012 7:45:40.602 4:39:46 PM AM 7.00 days 92P261A PMP NDE VIB X 92P261A PMP NDE VIB Y 92P261A PMP DE VIB X 92P261A PMP DE VIB Y 92P261A TURB DE VIB X 92P261A TURB DE VIB Y 92P261ABTURB DE VIB X 92P261A TURB NDE VIB X Turbine D.E/N.D.E VAH&VAHH is 25/37 Mm PK-PK 2/7/2012 2/8/20125:34:00 7:45:30.806 PM AM 8 / Boiler Feed Water Pumps Performance Loss
Unit 92-P261A Failure Thrust Bearing failure signs: Scored and smeared thrust pads Smeared Journal pads 9 / Boiler Feed Water Pumps Performance Loss
Unit 92-P261A Failure Cavitations' damage on 1 st stage Casing erosion Cavitations' damage 10 / Boiler Feed Water Pumps Performance Loss
Unit 92-P261A Failure RCFA initiated August 2011 and completed Oct. 2011 Casing erosion 11 / Boiler Feed Water Pumps Performance Loss
Performance Deterioration Pump A Optimum performance Deteriorated performance Other pumps performance 12 / Boiler Feed Water Pumps Performance Loss
RCFA-Unit 92-P261A 13 / Boiler Feed Water Pumps Performance Loss
RCFA-Unit 92-P261A RCFA Findings: Root Cause (Human) - Incorrect material specification of the pump casing for boiler feed water service led to major damage of casing inner walls and rotor parts Contributing Factor 1 (Latent) Insufficient online monitoring of pump performance due to inadequate instrumentation prevented effective pump health monitoring Contributing Factor 2 (Latent) Inadequate surveillance program for boiler feed water conditions led to a possible corrosive environment within pump flow path 14 / Boiler Feed Water Pumps Performance Loss
RCFA-Unit 92-P261A RCFA Recommendations: Immediate action: Purchase x6 new BFWPs with 12%Cr Stainless Steel casings (A487CA6NM) and replace the existing pumps with carbon steel casing (A216 WCB ) Medium action: Revise Equipment Strategy to perform bi-monthly online performance monitoring task including steam condensate dissolved oxygen and PH levels to ensure remaining within specification Long term action: Improve online monitoring: -Digital discharge pressure transmitter -Install flow measurement devices on the discharge and recirculation line 15 / Boiler Feed Water Pumps Performance Loss
Operational Risk Mitigation Contracts Dep. Electrical and Instrumentation Eng. Manufacturing Dep. Rotating Machinery Eng. Recovery Team Maintenance Process Eng. Asset Management Supply Dep. 16 / Boiler Feed Water Pumps Performance Loss
Operational Risk Mitigation Integrated Repair plan: x3 pumps repaired between Oct. 2011 and March 2012 x2 pumps were repaired used spare parts supplied from third party as fast repair. System reviewed for equipment reliability (Turbines, Motors, Automatic Recycle Valves, Instruments etc.) and corrective actions taken as appropriate Frequent measurement of discharge and recycle flow using clamp flow meter to assess pump performance Long term - Installation of x6 new pumps with stainless steel casing (procurement and installation time-14 months) 17 / Boiler Feed Water Pumps Performance Loss
Recommendations Results Performance for the repaired 3 units as interim solution was similar to OEM design. Ultimate replacement of all pumps by new stainless steel casing's units results in operating the BFW system with reliable units as per OEM design. Optimum performance 18 / Boiler Feed Water Pumps Performance Loss
Lessons Learned Follow API610 guidelines during procurement (material specifications versus fluid service) Improve datasheet and specification review during project FEED and procurement Improve online monitoring instruments required during plant design 19 / Boiler Feed Water Pumps Performance Loss October13
Questions? Authors: Amr Mohamed Gad RasGas Dr. Nicholas White RasGas asmohamedgad@rasgas.com.qa 20 / Boiler Feed Water Pumps Performance Loss
Backup 21 / Boiler Feed Water Pumps Performance Loss
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Operational Risk Mitigation Integrated Repair plan 24 / Boiler Feed Water Pumps Performance Loss