Tor Idhammar IDCON 1 LE
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Setting up a cost effective preventive maintenance process
Results Oriented Reliability and Maintenance Consulting and Training
What’s more important?
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3
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Do you see a problem?
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4
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Do We Know Exactly where We are Going?
PM Improvement
The Vision
CURRENT TIME
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How is Preventive Maintenance Defined?
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Failure & Break Down
When the failure has developed to the point that the equipment is unable to operate BREAK DOWN
FAILURE When the equipment condition SOURCE reaches an unacceptable level Event that initiate Failure developing
© Copyright IDCON
The failure is detected and reported
WWW.IDCON.COM
3&$5%(#
)$"!+'(*",# ).&,#
Priorities / Backlog
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© Copyright IDCON
(%'-,*'&.## !&(&/&0%#1# 0("$%0#
$%&'(# $%)&*$# $%(+$,# $%)%&(#
WWW.IDCON.COM
Essential Care Prevents Failures
• Lubrication • Alignment • Balancing • Detailed Cleaning • Operating Practices • Installation Practices • Filtration • Adjustments • Fixed Time Maintenance
© Copyright IDCON
Condition Monitoring Detects Failures
Objective
Provides a comparable reading
Measuring Pressure Flow Current, Voltage Distance Vibration Temperature Decibels Using Infrared Cameras Vibration Sensors Shock Pulse Measurement Ultrasonic Thickness Test Ultrasonic Listening (leaks) Oil Analysis Gauges, etc
Subjective
Provides no reading
Look Listen Feel Smell
WWW.IDCON.COM
Maintenance Methods – Existing Equipment
• OTB – Operate To Break-Down – Often Too Expensive
• FTM - Fixed Time Maintenance – Don’t Know Life Most of the Time
• CBM – Condition Based Maintenance – 70-85% Will Therefore Need CBM
© Copyright IDCON
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Thoughts • We know we will en up with M/E/I on-the-run and off-line inspections together with preventive measures (95% of our PM) • Do we focus on analysis and documentation or training and culture change?
© Copyright IDCON
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Centrifugal pump PM On-the-run CMS 127R • Temperatures • Vibration • Bolts and Fasteners • Noise and Vibration & cavitation • Oil - Level and Condition • Leaks • Pressures • Cleaning • Breather • Piping (and hangers) to and from Pump Off Line • Oil change (possibly oil sampling)
© Copyright IDCON
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Motor Inspection On-The-Run CMS 100 R • Cleanliness (fins, plugged airflows, etc) • Fan with strobe • Temperatures with (IR Temperature - Max? 170F (75C) • Vibration (feel or with Pen – Alarm 0.25 in/sec 6.35 mm/sec?) • Hold down bolts • Base • Condition of Junction Box and wires • Noise • Load (Current Reading) Shutdown • Winding test
© Copyright IDCON
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Break some Reliability Myths • Equipment Criticality is not the basis for inspection frequency
Severity – The consequence of failure if it happens Occurrence – The probability (or frequency) of a failure happening Detection – The probability of not detecting failure before it happens © Copyright IDCON
WWW.IDCON.COM
Equipment life is not the basis of inspection frequency • Example: Average motor life in your plant is 8 years => inspection frequency?
18 months
© Copyright IDCON
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Component Life
Bearing life under the same operating conditions, can vary from 1 to 25 years
L10
© Copyright IDCON
L90
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Component Life
Car tires life under the same operating conditions, may vary from 35,000 to 45,000 miles (6000-6500 mil)
35 K
45 K
Back © Copyright IDCON
WWW.IDCON.COM
Change in Condition
A belt will show signs of deterioration before breaking down
Break Down
Failure Developing Period
FDP © Copyright IDCON
WWW.IDCON.COM
Failure/ Break Down
When the failure has developed to the point that the equipment is unable to operate BREAK DOWN
FAILURE When the equipment condition SOURCE reaches an unacceptable level Event that initiate Failure developing
The failure is detected and reported
Source: källa till felet Break down: Haveri © Copyright IDCON
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Failure Developing Period
Break Down
A light bulb will break instantaneously without any signs of deterioration
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Selecting Maintenance Method What is the Function? What will happen if the function Break down? 1. Environmental damage or personal injury 2. High cost (lost production or damages) 3. Preserve value (Life)
99% • Obvious ANSWER BY: • P & ID • Ask operator
© Copyright IDCON
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Maintenance Methods – Existing Equipment
• OTB – Operate To Break-Down – Often Too Expensive
• FTM - Fixed Time Maintenance – Don’t Know Life Most of the Time
• CBM – Condition Based Maintenance – 70-85% Will Therefore Need CBM
© Copyright IDCON
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Hydraulic Cylinder
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Consequence of Break Down Analysis
© Copyright IDCON
0.2
16h * $40 = Parts
$640 3,000
$728
1
10h *$40 = Parts
$400 3,000
3,400
0.2
10h *$40 = Parts
$400 3,000
680
0.2*$4,000*10 = $8,000
1,000*0.2 =$200
728+8,000+200 =$8,928
0
0
$3,400
0
0
$680
WWW.IDCON.COM
Who GROUPS 1. Operator 2. Area Maintenance 3. In house maintenance expert 4. Outside expert Y Is it practical?
N
Go to next group
© Copyright IDCON
Do they know how?
Y
Implement Task
N N
Can they be trained in < X min?
Y
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Typical Operator Inspections
Belt and Coupling Condition with Stroboscope
Motor Temperature
Weep Hole Regulator
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Examples of Typical Maintenance Inspections Typical Maintenance Inspections
Places Impractical for Operators to Get To
Components that Require Experience
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Complex Systems
Vibration Analysis
Infrared Camera
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Paper Inspection Route Example
175
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CMS (100 Available)
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Handheld Example
Fahrenheit
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Accounting
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Results Oriented Maintenance
Most Organizations KNOW What to do Best Organizations Do it.
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CMS127R 7200 Falls of Neuse Road, Raleigh, North Carolina 27615 Phone (919) 847 8764, Fax (919) 847 8647 E-mail: [email protected], Web site: www.idcon.com
CONDITION MONITORING STANDARD Version 1.3 PUMP - CENTRIFUGAL The radial vanes cause pumpage, let’s say water, to rotate in the cylinder. Centrifugal force moves water towards the outside of the cylinder. Since the water can’t move outside the cylinder, it moves upward, and the water will rise from D1 to D2 on the outside edge. Vacuum is created because the water in the middle of the container is pushed down by atmospheric pressure. In this example, the water is collected in the receiver where it will escape through a discharge hole. The size of the discharge hole affects the pressure. A small discharge hole increases pressure, while a large discharge reduces pressure. In the center of the cylinder the escaping pumpage will generate a decrease in pressure causing suction from the supply source. Though many types of centrifugal pumps are on the market, all share this basic principle.
Version 1.2
CMS 127R Page 1 of 6
© IDCON, INC. 2003
© C o p y r i g h t I D C O N , I N C . – D o N o t C o p y
Basic Principle
KEY
WHAT
WHY
Check bearing temperature with an infrared temperature gun. Ball and roller bearings should not have a temperature exceeding 170 ºF. Try to get as close as possible to the bearings when taking the temperature. For example, for the Gould 3196 pump in the picture below; take the temperature in “the crack” on the inboard bearing. On the impeller side, take the temperature on the brass plate close to the bearing. If the pump is critical record and trend the temperatures.
Any substantial change in temperature usually indicates some fault, e.g.: x Excessive lubrication x Insufficient lubrication x Bearing damage x Overload x Induced Vibration x Shaft misalignment x Imbalanced impeller
Temperature
TEMPERATURE
Seal
Bolts and Fasteners
Courtesy: Gould’s Pumps
Version 1.2
Check foundation, base, and bolts for corrosion, cracks, and looseness.
Loose bolts and damaged base will cause misalignment and excessive vibration.
Packing: FOR DETAILS REFER TO CMS FOR PACKING Controlled bleed through packing, stuffing box temperature, seal water flow and pressure, gland gap, general mechanical integrity
NOTE: If tightening packing, recheck within one hour. If it is still leaking excessively, it must be replaced as soon as possible.
Mechanical seal: FOR DETAILS REFER TO CMS FOR MECHANICAL SEAL Seal temperature, seal water flow and pressure, general mechanical integrity.
CMS 127R Page 2 of 6
© IDCON, INC. 2003
KEY
WHAT
WHY
Check pump for abnormal noise and vibration. Cavitation sounds as small stones are going through the pump. Air bubbles implodes around the impeller and chips off small metal particles, often due to “starvation” on the side or increased pressure on the discharge side. Cavitation also causes high vibration in the pump. For more info on cavitation, look at the end of this document. Vibration can be detected by: 1. Feeling motor (subjectively) 2. Take vibration reading with vibration pen 3. Take full spectrum vibration reading
Noise and vibration is caused by: x Cavitation x Entrained air x Pump or drive not securely mounted x Impeller clogged or damaged x Bearing damage x Misalignment or coupling wear
Noise and Vibration
Try to detect unusually high vibration level by putting a hand on different spots on the pump. Take vibration readings at red dots. If a vibration pen is used, it is usually enough to take the vibration reading in the horizontal plane (horizontally mounted pump). The highest vibration value will usually appear in the horizontal plane. To ensure that the reading is comparable with the last readings taken on the same pump, mark where the vibration reading should be taken on the pump. Note that the alarm level for the vibration level highly depends on the RPM of the pump, but a good rule of thumb is to not exceed 0.25 in/sec.
A full vibration spectrum should be recorded every 2-3 weeks.
Version 1.2
CMS 127R Page 3 of 6
© IDCON, INC. 2003
Leaks and piping
Oil Level and oil condition
KEY
Version 1.2
WHAT
WHY
Oil level For oil bottle (see left picture below), the bearings are lubricated as long as lubricant is visible in the bottle. The round sight glasses should be installed so that the oil level measures to the center of the oil glass (see right picture below).
Level must be set carefully. Too much oil will cause leakage of oil and also increase bearing temperature.
Oil condition Visually inspect oil. Oil in pumps should have a golden color if regular mineral oil is used. If synthetic oil is used refer to original color of oil. Milky oil (as in picture below) indicates that there is water or air in the oil. Milky oil calls for corrective action. In order to get a more objective measure an oil checker or can be used for a quick check of the oil condition. If the pump is critical, or if the pump has had repetitive failures, a full oil analysis test should be performed.
Oil turns milky around 1000 ppm, where only about 15-25% of the original life is left if the problem isn’t corrected.
Check for visible leakage at pump mating surfaces, pump connections and fittings. Keep all live connections and fittings tight.
Air leaks on inlet will eventually cause cavitation in the pump. Discharge leaks will cause efficiency losses and spills.
Follow piping to and from pump, and look for leaks. Also check hangers for pipes supporting the pump piping.
Debris in oil may enter clarances in bearings and cause excessive wear.
Missing or damaged hangers may cause pipe strain and cause severe ware and misalignment of pump assembly.
CMS 127R Page 4 of 6
© IDCON, INC. 2003
KEY
WHAT
WHY
Detailed cleaning
Pressure gauge
Check discharge and inlet pressure if gauge is installed. Record pressure trends if pump is critical. Record flow if there is a gauge. More detailed … All pumps are designed for a certain flow [Gpm], and pressure [Psi] at startup. The flow and pressure determines “the head” of the pump is available to pump. The head is the height the pump can push the liquid. The designed flow and pressure rates are documented in graphs called “pump curves”. There is a best efficiency point for each pump, where the pump operates at the Best Efficiency Point (B.E.P). To check the B.E.P with pressure gauges, you’ll need: pump curves, pressure gauges. Do the following: 1. Calculate: ǻP=Discharge Pressure- Inlet pressure 2. Find ǻP on pump cure, and read flow rate on X-axis 3. Compare this flow with the B.E.P for the pump.
Inspect the breather condition. Make sure the breather isn’t clogged.
Breather
Breather
Version 1.2
CMS 127R Page 5 of 6
A 1% air leak may cause the capacity to decrease 10%. An 8 to 20% air leak will cause pump to lose its prime. Pump operating parameters often change over time due to scaling of pipes, valve installations, extension of piping, relocation of tanks etc. It’s therefore important to monitor pressures and BEP.
Clean the pump bowl, frame adapter, and power end from all dirt, stock, and grease. Clean around bolts and base, empty seal water basin (if any). BE CAREFUL AROUND ROTATING SHAFT AT PACKING!
Not enough pressure: - Speed may be to low - Air in the line - Wear rings worn - Impeller damaged - Packing defective
Cleaning can prevent corrosion, and will enable vibration readings, bolts, frame, and pump bowl inspection.
The breather filters air that enters the oil compartment of the pump. A clogged air filter may cause very high temperatures inside the oil compartment due to pressure changes.
© IDCON, INC. 2003
KEY
DISCUSSION There are two main types of cavitation. One is suction side related and this is by far the most common form (probably 90% of all known events). The other is discharge cavitation, which occurs rarely (10% of the time). SUCTION SIDE CAVITATION in its simplest terms is a restriction on the suction side of the pump, which does not allow enough fluid to enter the pump and be discharged. The pump reacts to pressure on the discharge side and produces a higher flow of liquid than can be drawn from the suction side. Restrictions either on the suctions side of the pump or atmospheric pressure decreases the flow of the pump, particularly in suction lift applications. The pump produces a higher flow of liquid than can be supplied to it, due to suction side restrictions.
Cavitation
DISCHARGE SIDE CAVITATION is a re3striction on the discharge side of the pump system, which constricts the flow out of the pump. Since liquid can’t escape, due to discharge side restrictions, it is recirculated in the pump casing, damaging the outer edge of the impeller and casing ring if there is one. DETECTING CAVITATION can be done by listening to the pump (with a stethoscope if necessary). Cavitation sounds just as if sand or gravel are circulating in the pump. Another sure sign of cavitation is that your discharge pressure gauge on the pump system will fluctuate wildly over a 5 –10 PSI range. Since the pump isn’t operating in its proper balance hydraulically, it is subjected to stresses within the pump machine that causes deflection and premature bearing and seal wear. If you are constantly changing seals and bearings in a pump, chances are that you have severe misalignment or cavitation. COMMON ROOT CAUSES OF CAVITATION 1. The pump was oversized by the specifying engineer. An oversized pump will try to pump more liquid than the system needs; the result is often suction side cavitation. 2. Change in system demands over time. The system may clog and flow may be restricted. System redesigns may have been done over time, which restricts flow. 3. Suction side lift applications (where the pump is located above the suction supply). Debris may slightly clog the suction side supply and thus starve the pump. 4. Temperature combined with marginal suction supply can act to cause cavitation. Temperature changes in for example tanks may cause the liquid to heat up enough to boil and create vapor, which will cause cavitation. FIXING CAVITATION TEMPORARILY For suction side cavitation, close the valve (that you should have) on the discharge side until the noise goes away. If this doesn’t work you may have discharge side cavitation, then open the valve instead until the noise goes away. You may think the flow will be restricted by closing the valve, it will not be restricted. You are simply pumping only liquid instead of liquid and vapor; therefore the flow will be the same. Another way to correct suction side cavitation is to recirculate some of the flow back to the suction side (make sure not to recirculate directly to the suction side). Source: Buckeye pumps
Version 1.2
CMS 127R Page 6 of 6
© IDCON, INC. 2003
Setting up a cost effective preventive maintenance process
Results Oriented Reliability and Maintenance Consulting and Training
What’s more important?
© Copyright IDCON
WWW.IDCON.COM
© Copyright IDCON
3
WWW.IDCON.COM
Do you see a problem?
© Copyright IDCON
4
WWW.IDCON.COM
© Copyright IDCON
WWW.IDCON.COM
Do We Know Exactly where We are Going?
PM Improvement
The Vision
CURRENT TIME
© Copyright IDCON
WWW.IDCON.COM
How is Preventive Maintenance Defined?
© Copyright IDCON
WWW.IDCON.COM
Failure & Break Down
When the failure has developed to the point that the equipment is unable to operate BREAK DOWN
FAILURE When the equipment condition SOURCE reaches an unacceptable level Event that initiate Failure developing
© Copyright IDCON
The failure is detected and reported
WWW.IDCON.COM
3&$5%(#
)$"!+'(*",# ).&,#
Priorities / Backlog
)$%2%,(*",#1# '",!*(*",# 3",*("$*,4#
3&*,(%,&,'%# ).&,,*,4#&,!# 0'-%!+.*,4#
'",(*,+"+0## *3)$"2%3%,(#
!"#
$%'"$!#
© Copyright IDCON
(%'-,*'&.## !&(&/&0%#1# 0("$%0#
$%&'(# $%)&*$# $%(+$,# $%)%&(#
WWW.IDCON.COM
Essential Care Prevents Failures
• Lubrication • Alignment • Balancing • Detailed Cleaning • Operating Practices • Installation Practices • Filtration • Adjustments • Fixed Time Maintenance
© Copyright IDCON
Condition Monitoring Detects Failures
Objective
Provides a comparable reading
Measuring Pressure Flow Current, Voltage Distance Vibration Temperature Decibels Using Infrared Cameras Vibration Sensors Shock Pulse Measurement Ultrasonic Thickness Test Ultrasonic Listening (leaks) Oil Analysis Gauges, etc
Subjective
Provides no reading
Look Listen Feel Smell
WWW.IDCON.COM
Maintenance Methods – Existing Equipment
• OTB – Operate To Break-Down – Often Too Expensive
• FTM - Fixed Time Maintenance – Don’t Know Life Most of the Time
• CBM – Condition Based Maintenance – 70-85% Will Therefore Need CBM
© Copyright IDCON
WWW.IDCON.COM
Thoughts • We know we will en up with M/E/I on-the-run and off-line inspections together with preventive measures (95% of our PM) • Do we focus on analysis and documentation or training and culture change?
© Copyright IDCON
WWW.IDCON.COM
Centrifugal pump PM On-the-run CMS 127R • Temperatures • Vibration • Bolts and Fasteners • Noise and Vibration & cavitation • Oil - Level and Condition • Leaks • Pressures • Cleaning • Breather • Piping (and hangers) to and from Pump Off Line • Oil change (possibly oil sampling)
© Copyright IDCON
WWW.IDCON.COM
Motor Inspection On-The-Run CMS 100 R • Cleanliness (fins, plugged airflows, etc) • Fan with strobe • Temperatures with (IR Temperature - Max? 170F (75C) • Vibration (feel or with Pen – Alarm 0.25 in/sec 6.35 mm/sec?) • Hold down bolts • Base • Condition of Junction Box and wires • Noise • Load (Current Reading) Shutdown • Winding test
© Copyright IDCON
WWW.IDCON.COM
Break some Reliability Myths • Equipment Criticality is not the basis for inspection frequency
Severity – The consequence of failure if it happens Occurrence – The probability (or frequency) of a failure happening Detection – The probability of not detecting failure before it happens © Copyright IDCON
WWW.IDCON.COM
Equipment life is not the basis of inspection frequency • Example: Average motor life in your plant is 8 years => inspection frequency?
18 months
© Copyright IDCON
WWW.IDCON.COM
Component Life
Bearing life under the same operating conditions, can vary from 1 to 25 years
L10
© Copyright IDCON
L90
WWW.IDCON.COM
Component Life
Car tires life under the same operating conditions, may vary from 35,000 to 45,000 miles (6000-6500 mil)
35 K
45 K
Back © Copyright IDCON
WWW.IDCON.COM
Change in Condition
A belt will show signs of deterioration before breaking down
Break Down
Failure Developing Period
FDP © Copyright IDCON
WWW.IDCON.COM
Failure/ Break Down
When the failure has developed to the point that the equipment is unable to operate BREAK DOWN
FAILURE When the equipment condition SOURCE reaches an unacceptable level Event that initiate Failure developing
The failure is detected and reported
Source: källa till felet Break down: Haveri © Copyright IDCON
WWW.IDCON.COM
Failure Developing Period
Break Down
A light bulb will break instantaneously without any signs of deterioration
© Copyright IDCON
WWW.IDCON.COM
Selecting Maintenance Method What is the Function? What will happen if the function Break down? 1. Environmental damage or personal injury 2. High cost (lost production or damages) 3. Preserve value (Life)
99% • Obvious ANSWER BY: • P & ID • Ask operator
© Copyright IDCON
WWW.IDCON.COM
Maintenance Methods – Existing Equipment
• OTB – Operate To Break-Down – Often Too Expensive
• FTM - Fixed Time Maintenance – Don’t Know Life Most of the Time
• CBM – Condition Based Maintenance – 70-85% Will Therefore Need CBM
© Copyright IDCON
WWW.IDCON.COM
Hydraulic Cylinder
© Copyright IDCON
WWW.IDCON.COM
Consequence of Break Down Analysis
© Copyright IDCON
0.2
16h * $40 = Parts
$640 3,000
$728
1
10h *$40 = Parts
$400 3,000
3,400
0.2
10h *$40 = Parts
$400 3,000
680
0.2*$4,000*10 = $8,000
1,000*0.2 =$200
728+8,000+200 =$8,928
0
0
$3,400
0
0
$680
WWW.IDCON.COM
Who GROUPS 1. Operator 2. Area Maintenance 3. In house maintenance expert 4. Outside expert Y Is it practical?
N
Go to next group
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Do they know how?
Y
Implement Task
N N
Can they be trained in < X min?
Y
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Typical Operator Inspections
Belt and Coupling Condition with Stroboscope
Motor Temperature
Weep Hole Regulator
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Examples of Typical Maintenance Inspections Typical Maintenance Inspections
Places Impractical for Operators to Get To
Components that Require Experience
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Complex Systems
Vibration Analysis
Infrared Camera
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Paper Inspection Route Example
175
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CMS (100 Available)
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Handheld Example
Fahrenheit
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Accounting
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Results Oriented Maintenance
Most Organizations KNOW What to do Best Organizations Do it.
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CMS127R 7200 Falls of Neuse Road, Raleigh, North Carolina 27615 Phone (919) 847 8764, Fax (919) 847 8647 E-mail: [email protected], Web site: www.idcon.com
CONDITION MONITORING STANDARD Version 1.3 PUMP - CENTRIFUGAL The radial vanes cause pumpage, let’s say water, to rotate in the cylinder. Centrifugal force moves water towards the outside of the cylinder. Since the water can’t move outside the cylinder, it moves upward, and the water will rise from D1 to D2 on the outside edge. Vacuum is created because the water in the middle of the container is pushed down by atmospheric pressure. In this example, the water is collected in the receiver where it will escape through a discharge hole. The size of the discharge hole affects the pressure. A small discharge hole increases pressure, while a large discharge reduces pressure. In the center of the cylinder the escaping pumpage will generate a decrease in pressure causing suction from the supply source. Though many types of centrifugal pumps are on the market, all share this basic principle.
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© C o p y r i g h t I D C O N , I N C . – D o N o t C o p y
Basic Principle
KEY
WHAT
WHY
Check bearing temperature with an infrared temperature gun. Ball and roller bearings should not have a temperature exceeding 170 ºF. Try to get as close as possible to the bearings when taking the temperature. For example, for the Gould 3196 pump in the picture below; take the temperature in “the crack” on the inboard bearing. On the impeller side, take the temperature on the brass plate close to the bearing. If the pump is critical record and trend the temperatures.
Any substantial change in temperature usually indicates some fault, e.g.: x Excessive lubrication x Insufficient lubrication x Bearing damage x Overload x Induced Vibration x Shaft misalignment x Imbalanced impeller
Temperature
TEMPERATURE
Seal
Bolts and Fasteners
Courtesy: Gould’s Pumps
Version 1.2
Check foundation, base, and bolts for corrosion, cracks, and looseness.
Loose bolts and damaged base will cause misalignment and excessive vibration.
Packing: FOR DETAILS REFER TO CMS FOR PACKING Controlled bleed through packing, stuffing box temperature, seal water flow and pressure, gland gap, general mechanical integrity
NOTE: If tightening packing, recheck within one hour. If it is still leaking excessively, it must be replaced as soon as possible.
Mechanical seal: FOR DETAILS REFER TO CMS FOR MECHANICAL SEAL Seal temperature, seal water flow and pressure, general mechanical integrity.
CMS 127R Page 2 of 6
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KEY
WHAT
WHY
Check pump for abnormal noise and vibration. Cavitation sounds as small stones are going through the pump. Air bubbles implodes around the impeller and chips off small metal particles, often due to “starvation” on the side or increased pressure on the discharge side. Cavitation also causes high vibration in the pump. For more info on cavitation, look at the end of this document. Vibration can be detected by: 1. Feeling motor (subjectively) 2. Take vibration reading with vibration pen 3. Take full spectrum vibration reading
Noise and vibration is caused by: x Cavitation x Entrained air x Pump or drive not securely mounted x Impeller clogged or damaged x Bearing damage x Misalignment or coupling wear
Noise and Vibration
Try to detect unusually high vibration level by putting a hand on different spots on the pump. Take vibration readings at red dots. If a vibration pen is used, it is usually enough to take the vibration reading in the horizontal plane (horizontally mounted pump). The highest vibration value will usually appear in the horizontal plane. To ensure that the reading is comparable with the last readings taken on the same pump, mark where the vibration reading should be taken on the pump. Note that the alarm level for the vibration level highly depends on the RPM of the pump, but a good rule of thumb is to not exceed 0.25 in/sec.
A full vibration spectrum should be recorded every 2-3 weeks.
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Leaks and piping
Oil Level and oil condition
KEY
Version 1.2
WHAT
WHY
Oil level For oil bottle (see left picture below), the bearings are lubricated as long as lubricant is visible in the bottle. The round sight glasses should be installed so that the oil level measures to the center of the oil glass (see right picture below).
Level must be set carefully. Too much oil will cause leakage of oil and also increase bearing temperature.
Oil condition Visually inspect oil. Oil in pumps should have a golden color if regular mineral oil is used. If synthetic oil is used refer to original color of oil. Milky oil (as in picture below) indicates that there is water or air in the oil. Milky oil calls for corrective action. In order to get a more objective measure an oil checker or can be used for a quick check of the oil condition. If the pump is critical, or if the pump has had repetitive failures, a full oil analysis test should be performed.
Oil turns milky around 1000 ppm, where only about 15-25% of the original life is left if the problem isn’t corrected.
Check for visible leakage at pump mating surfaces, pump connections and fittings. Keep all live connections and fittings tight.
Air leaks on inlet will eventually cause cavitation in the pump. Discharge leaks will cause efficiency losses and spills.
Follow piping to and from pump, and look for leaks. Also check hangers for pipes supporting the pump piping.
Debris in oil may enter clarances in bearings and cause excessive wear.
Missing or damaged hangers may cause pipe strain and cause severe ware and misalignment of pump assembly.
CMS 127R Page 4 of 6
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KEY
WHAT
WHY
Detailed cleaning
Pressure gauge
Check discharge and inlet pressure if gauge is installed. Record pressure trends if pump is critical. Record flow if there is a gauge. More detailed … All pumps are designed for a certain flow [Gpm], and pressure [Psi] at startup. The flow and pressure determines “the head” of the pump is available to pump. The head is the height the pump can push the liquid. The designed flow and pressure rates are documented in graphs called “pump curves”. There is a best efficiency point for each pump, where the pump operates at the Best Efficiency Point (B.E.P). To check the B.E.P with pressure gauges, you’ll need: pump curves, pressure gauges. Do the following: 1. Calculate: ǻP=Discharge Pressure- Inlet pressure 2. Find ǻP on pump cure, and read flow rate on X-axis 3. Compare this flow with the B.E.P for the pump.
Inspect the breather condition. Make sure the breather isn’t clogged.
Breather
Breather
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A 1% air leak may cause the capacity to decrease 10%. An 8 to 20% air leak will cause pump to lose its prime. Pump operating parameters often change over time due to scaling of pipes, valve installations, extension of piping, relocation of tanks etc. It’s therefore important to monitor pressures and BEP.
Clean the pump bowl, frame adapter, and power end from all dirt, stock, and grease. Clean around bolts and base, empty seal water basin (if any). BE CAREFUL AROUND ROTATING SHAFT AT PACKING!
Not enough pressure: - Speed may be to low - Air in the line - Wear rings worn - Impeller damaged - Packing defective
Cleaning can prevent corrosion, and will enable vibration readings, bolts, frame, and pump bowl inspection.
The breather filters air that enters the oil compartment of the pump. A clogged air filter may cause very high temperatures inside the oil compartment due to pressure changes.
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KEY
DISCUSSION There are two main types of cavitation. One is suction side related and this is by far the most common form (probably 90% of all known events). The other is discharge cavitation, which occurs rarely (10% of the time). SUCTION SIDE CAVITATION in its simplest terms is a restriction on the suction side of the pump, which does not allow enough fluid to enter the pump and be discharged. The pump reacts to pressure on the discharge side and produces a higher flow of liquid than can be drawn from the suction side. Restrictions either on the suctions side of the pump or atmospheric pressure decreases the flow of the pump, particularly in suction lift applications. The pump produces a higher flow of liquid than can be supplied to it, due to suction side restrictions.
Cavitation
DISCHARGE SIDE CAVITATION is a re3striction on the discharge side of the pump system, which constricts the flow out of the pump. Since liquid can’t escape, due to discharge side restrictions, it is recirculated in the pump casing, damaging the outer edge of the impeller and casing ring if there is one. DETECTING CAVITATION can be done by listening to the pump (with a stethoscope if necessary). Cavitation sounds just as if sand or gravel are circulating in the pump. Another sure sign of cavitation is that your discharge pressure gauge on the pump system will fluctuate wildly over a 5 –10 PSI range. Since the pump isn’t operating in its proper balance hydraulically, it is subjected to stresses within the pump machine that causes deflection and premature bearing and seal wear. If you are constantly changing seals and bearings in a pump, chances are that you have severe misalignment or cavitation. COMMON ROOT CAUSES OF CAVITATION 1. The pump was oversized by the specifying engineer. An oversized pump will try to pump more liquid than the system needs; the result is often suction side cavitation. 2. Change in system demands over time. The system may clog and flow may be restricted. System redesigns may have been done over time, which restricts flow. 3. Suction side lift applications (where the pump is located above the suction supply). Debris may slightly clog the suction side supply and thus starve the pump. 4. Temperature combined with marginal suction supply can act to cause cavitation. Temperature changes in for example tanks may cause the liquid to heat up enough to boil and create vapor, which will cause cavitation. FIXING CAVITATION TEMPORARILY For suction side cavitation, close the valve (that you should have) on the discharge side until the noise goes away. If this doesn’t work you may have discharge side cavitation, then open the valve instead until the noise goes away. You may think the flow will be restricted by closing the valve, it will not be restricted. You are simply pumping only liquid instead of liquid and vapor; therefore the flow will be the same. Another way to correct suction side cavitation is to recirculate some of the flow back to the suction side (make sure not to recirculate directly to the suction side). Source: Buckeye pumps
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