Pump Wisdom Problem Solving for Operators and Specialists By Heinz P Bloch

Pages 226
Views 815
Size 10.0 MiB
Downloads 123
Pump Wisdom Problem Solving for Operators and Specialists By Heinz P Bloch


Table of Contents

1. Principles of Centrifugal Process Pumps 1
Pump performance: Head and flow
Operation at zero flow
Impellers and rotors
The meaning of specific speed
Process pump types
Process pump mechanical response to flow changes
Recirculation and cavitation
The importance of suction specific speed
What we have learned
2. Pump Selection and Industry Standards 15
Why insist on better pumps
ANSI and ISO versus API pumps
What we have learned
3. Foundations and Base Plates 23
Securing pumps in place—with one exception
Why not to install pump sets in the as-shipped condition
Conventional versus pre-filled base plate installations
Epoxy prefilled base plates
How to proceed if there is no access to specialist firms
What we have learned: Checklist of foundation and base plate topics
4. Piping, Stationary Seals, and Gasketing 35
Pipe installation and support
Sliding supports and installation sequence deserve special attention
Monitoring pipe stress while bolting up
Flange leakage
What to do prior to gasket insertion
Spiral wound and kammprofile gaskets
Pipe, hydraulic tubing, or flexible connections?
Concentric versus eccentric reducers
Vibration problems in piping
What we have learned on piping and gasketing topics
5. Rolling Element Bearings 49
Bearing selection overview and windage as a design problem
Radial versus axial (thrust) bearings
Oil levels, multiple bearings, and different bearing orientations
Upgrading and retrofit opportunities
Bearing cages
Bearing preload and clearance effects
Bearing dimensions and mounting tolerances
What we have learned
6. Lubricant Application and Cooling Considerations 69
Lubricant level and oil application
Issues with oil rings
Pressure and temperature balance in bearing housings
Cooling not needed on pumps with rolling element bearings
Oil delivery by constant level lubricators
Black oil
Lube application as oil mist (oil fog)
Desiccant breathers and expansion chambers
What we have learned
7. Lubricant Types and Key Properties 83
Lubricant viscosities
When and why high film strength synthetic lubricants are used
Lubricants for oil mist systems
What we have learned
8. Bearing Housing Protection and Cost Justification 91
Noncontacting bearing protector seals
Contacting bearing protector seals
How venting and housing pressurization affect bearing
protector seal performance
Cost justification overview
Advanced bearing housing (bearing protector) seal summary
What we have learned
9. Mechanical Sealing Options for Long Life 99
Still using packing?
General overview of mechanical seals
All flush plans have advantages and disadvantages
Always obtain the full picture
Seal chamber pumping ring (circulating device) technologies
Lessons apply to many services
What we have learned
10. Pump Operation 115
Starting centrifugal pumps
Surveillance of pump operation
Centrifugal pump shutdown
What we have learned
11. Impeller Modifications and Pump Maintenance 121
Maintenance essentials
Superior maintenance requires upgrading
Impeller upgrading with inducers
Distance from impeller tip to stationary internal casing components
Impeller trimming
Impeller wear rings
Vane tip overfiling and underfiling
What we have learned
12. Lubrication Management 131
How bad is water contamination?
Avoid solids contamination
Avoid questionable storage and transfer practices
Periodic audits
What we have learned
13. Pump Condition Monitoring: Pump Vibration,
Rotor Balance, and Effect on Bearing Life 139
Vibration and its effect on bearing life
Monitoring methods differ
Vibration acceptance limits
Causes of excessive vibration
Rotor balancing
What we have learned
14. Drivers, Couplings, and Alignment 153
Driver selection
Coupling selection and installation
Installation and removal
Alignment and quality criteria
Consequences of misalignment
Thermal rise and predefinition of growth
What we have learned
15. Fits, Dimensions, and Related Misunderstandings 163
Low incremental cost of better pumps
Pump pedestals and bearing housings should not be water-cooled
Summary of bearing-related issues
Constant level lubricators
Bearing housing protector seals (“bearing isolators”)
Motor lubrication summary
Mechanical seal issues
Hydraulic issues
Impeller hydraulics
Mechanical improvement or upgrade options
Process pump repair dimensions
What we have learned
Failure Statistics and Structured Failure Analysis 183
Mean time between failures (MTBF) and repair cost calculations
Performing your own projected MTBF calculations
Older pumps versus newer pumps
Reliability reviews start before purchase
Structured failure analysis strategies solve problems
The “FRETT” approach to eradicating repeat failures of pumps
What we have learned