Amr Mohamed Gadpump casing for boiler feed water service led to major damage. of casing inner walls...

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 5 major worldwide conferences

Boiler Feed Water Pumps Performance Loss

Amr Mohamed Gad– RasGasDr.Nicholas White – RasGas

Arbain Bin Mahmood– RasGas

2nd Middle East Turbo Machinery Symposium 17th – 21st March 2013

1 / Boiler Feed Water Pumps Performance Loss | March13

Index

• RGX2 Steam Condensate System

• Problem Summary

• Troubleshooting History

• Unit 92-A261A –Failure

• Performance Deterioration

• RCFA-Unit 92-P261A

• Operational Risk Mitigation

• Recommendations Results

• Lessons Learned


RGX2 Steam Condensate System

x6 No. BFW

Steam condensate system set up at RGX2• Total of x6 Boiler Feed Water Pumps (x4 steam driven pumps and

x2 motor driven pumps).

Operating philosophy N+2:• x4 in service and x2 Stand by operation.



Pump specifications:

• Rated capacity 750 M3/hr

• Rated power 1.7 MW

• Differential head 680m

• Horizontally split casing

• 4 stage with double inlet impeller



New pump before installation Old pump at skid in RGX2


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 (flow rate and head rise)

• During the 25 months of operation, thrust bearing temperature again reached high alarm level and pump was found seized upon inspection


Troubleshooting History

Historical RecordsUnit 92-P261A historical events shown on a timeline

92P261A PMP NDE BRG TEMP92P261A PMP NDE BRG TEMP92P261B PMP NDE BRG TEMP92P261B PMP NDE BRG TEMP92P261A PMP NDE BRG TEMP92P261A PMP NDE BRG TEMP92P261B PMP NDE BRG TEMP92P261B PMP NDE BRG TEMPOIL TO PMP & TURB 92P261AWB FR 92P261ABCDWB FR 92P261ABCD

92TI6864AA.PV

92TI6864AB.PV

92TI6864BA.PV

92TI6864BB.PV

92TI6865AA.PV

92TI6865AB.PV

92TI6865BA.PV

92TI6865BB.PV

92PI6802A.PV

92PI6517.PV

92PI6518.PV

Plot-0

10/6/2009 8:20:59.518 AM 10/13/2010 8:20:59.518 AM372.00 days

20

40

60

80

100

0

120

61.994

61.984

7.4481E-02

75.849

74.042

29.695

32.43

58.462

65.055

28.376

32.137

pump’s thrust bearing temperature increase due to bearing degradation over one year – alarm level reach xx deg C


Troubleshooting History

\\RTIS67\92VI6808AA.P12.015UM PP\\RTIS67\92VI6808AB.P11.233UM PP\\RTIS67\92VI6809AA.P20.928UM PP\\RTIS67\92VI6809AB.P25.958UM PP\\RTIS67\92VI6810AA.P8.1319UM PP\\RTIS67\92VI6810AB.P8.1319UM PP\\RTIS67\92VI6810BA.P6.2027UM PP\\RTIS67\92VI6811AA.P8.9133UM PP\\RTIS67\92VI6811AB.P7.7411UM PP

92P261A PMP NDE VIB X92P261A PMP NDE VIB Y92P261A PMP DE VIB X92P261A PMP DE VIB Y92P261A TURB DE VIB X92P261A TURB DE VIB Y92P261ABTURB DE VIB X92P261A TURB NDE VIB X

2/8/2012 7:45:30.806 AM2/1/2012 7:45:40.602 AM 7.00 days

Plot-0

4

9

14

19

24

28

2/1/2012 4:39:46 PM

11.62410.84218.60825.5928.13198.13196.20278.91337.3748

2/7/2012 5:34:00 PM

11.62411.23321.31926.3498.13197.74115.03058.91337.3748

Unit 92-P261A -Vibration readings

Pump D.E

radial vibration

Pump N.D.E

radial vibration

Turbine D.E & N.D.E

radial vibration

Pump D.E/N.D.E VAH&VAHH is 50/70 Mm PK-PK

Turbine D.E/N.D.E VAH&VAHH is 25/37 Mm PK-PK


Unit 92-A261A –Failure

Scoring and smear on thrust pads Smeared Journal pads

Thrust Bearing failure signs:



Cavitation damage

Cavitation damage on 1st stage

Casing erosion



Casing erosion

RCFA initiated August 2011 and completed October 2011


Performance Deterioration

Optimum performance Deteriorated performance Other pumps performance

Pump A

Other

5

pumps


RCFA-Unit 92-P261A


RCFA-Unit 92-P261A

RCFA – Findings

• Root Cause (Human) - Incorrect material specification of the pump casing for boiler feed water service led to major damageof 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


RCFA-Unit 92-P261A

RCFA – Recommendations

• Immediate action: Purchase x6 new BFWPs with 12%Cr Stainless Steel casings and replace the existing pumps with carbon steel casing

• Medium action: Revise the Equipment Strategy to perform a bi-monthly online performance monitoring task including steam condensate dissolved oxygen and pH levels to ensure they remain within specification

• Long term action: Improve online monitoring by installation of the following:-Digital discharge pressure transmitter-Install flow measurement devices on the discharge and recirculation line


Operational Risk Mitigation

Recovery TEAM

Rotating Machinery Eng.

Maintenance Process Eng.

Manufacturing Dep.

Contracts Dep.

Supply Dep.

Electrical and Instrumentation Eng.

Asset Management



Integrated Repair plan• x3 pumps repaired between October 2011 and March 2012• x2 pumps were repaired used spare parts manufactured by

third party as fast track repair to save time

• System reviewed for equipment reliability (Turbines, Automatic Recycle Valves, Instruments etc.) and corrective actions taken as appropriate

• Close monitoring and measurement of discharge and recycle flow using clamp flow meter to assess pump performance

• Long term - Installation of x6 new BFW pumps with stainless steel casing (procurement and installation during 14 months)


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


Lessons Learned

• Follow API610 guidelines during equipment procurement(material specifications versus fluid service)

• Improve datasheet and specification review during project FEED and procurement

• Improve online monitoring instruments required during plant design


Questions?

Authors:

Amr Mohamed Gad – RasGas

Dr. Nicholas White - RasGas

Arbain Mahmood – RasGas

[email protected]


Backup


23 | RasGas classification/title heading | December 12


Integrated Repair plan


Amr Mohamed Gadpump casing for boiler feed water service led to major damage. of casing inner walls...

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