Centrifugal Pump Vibrations: The Causes by Steven J. Hrivnak, P.E. - PowerPoint PPT Presentation

Centrifugal Pump Vibrations: The Causes by Steven J. Hrivnak, P.E. Associate Mechanical Engineer Tennessee Eastman Eastman Chemical Company EASTMAN

FAULTS REPORTED OVER 3 YEARS

Vibration: a measure of reliability! a measure of reliability! Vibration: Poorly installed and operated pumps average .178 in/sec overall vibration and have 6 months life. Properly installed pumps average .071 in/sec overall vibration and have 60 months life. EASTMAN

Three Basic Causes of Pump Three Basic Causes of Pump Vibrations: Vibrations: • Mechanically Induced Mechanically Induced • • System Induced System Induced • • Operation Induced Operation Induced •

Mechanically Induced Mechanically Induced • Bad bearings Bad bearings • • Bent Shaft Bent Shaft • • Unbalanced Rotor Unbalanced Rotor • • Check Valve Installed Backwards Check Valve Installed Backwards • • Mis Mis-Alignment -Alignment • • Looseness Looseness • Soft Foot Soft Foot • • Maximum Size Impeller Maximum Size Impeller •

System Induced System Induced • Partially/Plugged Strainer Partially/Plugged Strainer • • Clogged Impeller or Suction Line Clogged Impeller or Suction Line • • Installation Installation •

PIPING?

Foundations Foundations and and Baseplates Baseplates

The mass ratio must be 3:1 to The mass ratio must be 3:1 to minimize vibration minimize vibration

Operationally Induced Operationally Induced • Cavitation Cavitation • • Flow Flow • • Speed Speed • • Insufficient Immersion of Suction Pipe or Insufficient Immersion of Suction Pipe or • Bell Bell

Cavitation and Flow Cavitation and Flow

Head High Temp. Rise Low Flow Cavitation Low Bearing and Seal Life Reduced Impeller Life Suction Recirculation Operating Off The B.E.P. Discharge Recirculation Flow B.E.P. Low Bearing and Seal Life Cavation

You can’t run a pump with suction You can’t run a pump with suction and discharge valves closed! and discharge valves closed!

Minimum Flow Minimum Flow 1750 rpm 15-20% BEP Flow 1750 rpm 15-20% BEP Flow 3500 rpm 30-50% BEP Flow 3500 rpm 30-50% BEP Flow

Maximum Flow Maximum Flow 110-115% BEP Flow 110-115% BEP Flow

Speed Speed

Suction Pipe Immersion Suction Pipe Immersion

Conclusions Conclusions Avoid Max Size Impellers Avoid Max Size Impellers EASTMAN

Conclusions Conclusions Avoid Max Size Impellers Avoid Max Size Impellers Keep speed to 1750 max Keep speed to 1750 max EASTMAN

Conclusions Conclusions Avoid Max Size Impellers Avoid Max Size Impellers Keep speed to 1750 max Keep speed to 1750 max Keep flow in design range Keep flow in design range EASTMAN

Conclusions Conclusions Avoid Max Size Impellers Avoid Max Size Impellers Keep speed to 1750 max Keep speed to 1750 max Keep flow in design range Keep flow in design range Grout your baseplates Grout your baseplates EASTMAN

Conclusions Conclusions Avoid Max Size Impellers Avoid Max Size Impellers Keep speed to 1750 max Keep speed to 1750 max Keep flow in design range Keep flow in design range Grout your baseplates Grout your baseplates Use proper piping Use proper piping EASTMAN

Conclusions Conclusions Avoid Max Size Impellers Avoid Max Size Impellers Keep speed to 1750 max Keep speed to 1750 max Keep flow in design range Keep flow in design range Grout your baseplates baseplates Grout your Use proper piping Use proper piping Avoid hydraulically induced problems like Avoid hydraulically induced problems like cavitation, and suction and discharge re-circulation, cavitation, and suction and discharge re-circulation, submergence. submergence. EASTMAN

5 PUMPS - 6 YR. MTBF 5 PUMPS - 6 YR. MTBF 8 PUMPS - 5 YR. MTBF 8 PUMPS - 5 YR. MTBF 15 PUMPS - 4 YR. MTBF 15 PUMPS - 4 YR. MTBF