by Steven J. Hrivnak, P.E. Associate Mechanical Engineer Tennessee Eastman Eastman Chemical Company
FAULTS REPORTED OVER 3 YEARS
FAULTS REPORTED OVER 3 YEARS
Vibration: a a measure of reliability! reliability! 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 Vibrations:
• Mechanically Mechanically Induced • System System Induced • Operation Operation Induced
Mechanically Induced Bad bearings • Bad Bent Shaft • Bent Unbalanced Unbalanced Rotor • Unbalanced Check Valve Installed Backwards • Check •
Mis-Alignment
Looseness • Looseness Soft Foot • Soft Maximum Size Impeller • Maximum
System Induced
Partially/Plugged Strainer • Partially/Plugged Clogged Impeller or Suction Line • Clogged Installation • Installation
PIPING?
Foundations and Baseplates
The mass ratio must be 3:1 to minimize vibration
Operationally Induced Cavitation • Cavitation Flow • Flow Speed • Speed Insufficient Immersion of Suction Pipe or • Insufficient Bell
Cavitation and Flow
Operating Off The B.E.P.
e s i R .
d a e H
m e T h i H
n o i t a t i v a C w o l F w o L
e f i L l a e S d n a g n i r a e B w o L
e f i L r e l l e p m I d e c u d e R
n o i t a l u c r i c e R n o i t c u S
n o i t a l u c r i c e R e g r a h c s i D
. P . E . B e d f n i a L g l n a e i r S a e B w o L
Flow
n o i t a v a C
You can’t run a pump with suction and discharge valves closed!
Minimum Flow
1750 rpm 15-20% BEP Flow 3500 rpm 30-50% BEP Flow
Maximum Flow
110-115% BEP Flow
Speed
Suction Pipe Immersion
Conclusions Avoid Max Size Impellers
EASTMAN
Conclusions Avoid Max Size Impellers Keep speed to 1750 max
EASTMAN
Conclusions Avoid Max Size Impellers Keep speed to 1750 max Keep flow in design range
EASTMAN
Conclusions Avoid Max Size Impellers Keep speed to 1750 max Keep flow in design range Grout your baseplates baseplates
EASTMAN
Conclusions Avoid Max Size Impellers Keep speed to 1750 max Keep flow in design range Grout your baseplates Use proper piping
EASTMAN
Conclusions Avoid Max Size Impellers Keep speed to 1750 max Keep flow in design range Grout your baseplates baseplates Use proper piping Avoid hydraulically induced problems like cavitation, and suction and discharge re-circulation, submergence. EASTMAN
