Workhorses in many different industries, including the oil industry, water industry, chemical industry, food industry, and pharmaceutical industry to name a few, pumps are a vital contributor to maintaining and increasing the flow of production. In fact, the pump industry itself is a multi-billion dollar global business.
Taking the unique approach of addressing both pump operators and pump designers, Pump Wisdom explains the causes of failure in centrifugal pump function?whether it's pump selection, overlooked installation criteria, or the accumulation of small deviations?and maps out remedies with well defined methods that target specific issues, rather than focusing on technical generalities and theory. Clearly written and concise, Pump Wisdom relies on proven tactics for reducing pump vulnerabilities and correcting imbalances between hydraulic assembly and mechanical assembly. In addition, it supplies sound tips for detecting and rectifying risky shortcuts taken by pump designers and manufacturers. Pump Wisdom also: - Provides a concise explanation of how pumps function - Details the specifications to be considered when purchasing a pump - Provides tips on the installation of centrifugal pumps in process plants - Written in concise language that avoids excessive mathematical treatment - Explains pump hydraulics in easy to understand terms - Emphasizes the mechanical aspects of pumps with coverage on bearings, seals, impeller trimming, lubricant application, lubricant types, and more
Pump Wisdom sheds light on the techniques for stabilizing pump performance and maximizing pump efficiency. Its concise format allows readers to strike directly at the heart of the problem?and helps them devise strategies to prevent costly failures before they occur.
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
References
2 Pump Selection and Industrial Standards 15
Why insist on better pumps
ANSI and ISO vs API pumps
What we have learned
References
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 vs pre-filled base plate installations
Epoxy pre-filled base plates
How to proceed if there is no access to specialist firms
What we have learned: Checklist of foundation and base plate topics
References
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
Gusseting
Concentric vs eccentric reducers
Vibration problems in piping
What we have learned on piping and gasketing topics
References
5 Rolling Element Bearings 49
Bearing selection overview and windage as a design problem
Radial vs 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
References
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
References
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
References
8 Bearing Housing Protection and Cost-Justification 91
Non-contacting 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
References
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 to apply to many services
What we have learned
Bibliography
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 tips to stationary internal casing components
Impeller trimmings
Impeller wear rings
Vane tip overfiling and underfiling
What we have learned
References
12 Lubrication Management 131
How bad is water contamination?
Avoid solids contamination
Avoid questionable storage and transfer practices
Periodic audits
What we have learned
References
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
References
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
References
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
References
16 Failure Statistics and Successful Failure Analysis 183
Mean time between failures and repair cost calculations
Performing your own projected MTBF calculations
Older pumps vs 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
References
Index 199
