Maintenance, Reliability and Troubleshooting in Rotating Machinery

1 Cover

2 Title Page

3 Copyright

4 Dedication

5 Preface

6 Acknowledgements

7 Part I: GENERAL RELIABILITY ADVICE 1 Machinery Reliability Management in a Nutshell Criticality Environmental Consequences Safety Consequences Equipment History Safeguards Compressor Operating Limits Compressor Flow Limits Critical Speeds Horsepower Limits Temperatures Layers of Machinery Protection Machinery Reliability Assessment Example History Safeguards Conclusion Closing Remarks 2 Useful Analysis Tools for Tracking Machinery Reliability Commonly Used Metrics for Spared Machinery: Additional Reliability Assessment Tools for Spared Machines Cumulative Failure Trends Metrics for Critical Machines Availability Critical Machine Events Process Outage Trends Process Outage Related to Machinery Outages Planned Maintenance Percentage (PMP) Reliability Analysis Capabilities of your CMMS Software 3 Improving the Effectiveness of Plant Operators Look, Listen and Feel Applying Look, Listen, and Feel Techniques to Troubleshooting Why the Operator’s Input is Important to the Troubleshooting Process Operator Tools Understanding the Equipment – Pumps, Seals and Sealing Support Systems Centrifugal Pump Relationships to Remember Positive Displacement Pump Relationships to Remember Mechanical Seals Capital Projects Writing Quality Work Request Procedures (Procedures and Decision Trees) Must Give Operators Feedback Must be Required to Use their Training Discipline Conclusion Appendix A References 4 Spare Parts Strategies for Optimizing Rotating Machinery Availability Some Stocking Examples Capital Spares Insurance Spares Analyzing Spare Part Inventories Using Monte Carlo Simulations Closing 5 Switch-Over Methodology and Frequency Optimization for Plant Machinery Machinery Switchover Frequency Optimization Benefits Time-Dependent Issues Involved in Setting Switchover Frequency for Standby Machines Frequent Switchover Introduces the Following Negative Impact to Rotating Equipment Calculation of Start-Stop Damaging Cycles for A, B Configured Equipment: See Definitions Below for More Information Definitions Examples of Short Start-Stop Intervals in Process Machinery Philosophy of Reliability-Centered Switchover Strategy

8 Part II: DESIGN AUDITS AND IMPROVEMENT IDEAS 6 Evaluating Centrifugal Pumps in Petrochemical Applications Crude Oil Processing Crude Oil Distillation Properties of Distillation and Fractionator Fractions Natural Gas Processing: NGL Processing Centrifugal Pump Design Audits Design Standards The Materials of Construction The Hydraulic Fit The NPSH Margin [4] Seal and Seal Flush Design Challenging Pump Applications Pumps Operating in Parallel Pump Liquids with Low Densities Low NPSH Services How an Impeller’s Suction Specific Speed Affects the Required NPSH [4] Pumps Handling a Liquid with Varying Densities Slurry Pumps [5] Hot Pumps with Galling Tendencies Starting Hot Pumps [6] High Temperature Concerns Gaskets [7] O-Rings How Processing Issues Can Affect Pump Reliability Summary Acknowledgement References 7 Practical Ways to Improve Mechanical Seal Reliability Seal Reliability Tracking MTBR Data from Across the Industry Reliability Tracking Tools Bad Actors Mechanical Seal Best Practices Improved Mechanical Seal Support System Designs [2] Reducing Potential Leak Points Simplifying Operation and Maintenance Building Better Seal Support Systems Common Mechanical Sealing Design Challenges Common Considerations for Flush Plans General Seal Piping Plan Recommendations Ways to Improve Seal Reliability Performance Seal Failure Analysis [4] Common Seal Failure Modes Seal Failure Inspection Notes Possible Causes Meeting with Manufacturer Writing the Seal Failure Report with Recommendations Post-Analysis Activities Justifying Seal Upgrades Closing Thoughts References 8 Proven Ways to Improve Steam Turbine Reliability Repairs versus Overhauls Expected Lifetimes of Steam Turbines and Their Components Common Failure Modes Improvement Reliability by Design Acknowledgements 9 General Purpose Steam Turbine Reliability Improvement Case Studies Governor Valve Packing Gland Leakage: Sealing & Reliability Improvements Steam Turbines Carbon Seals Upgrade to Mechanical Seals Typical Benefits of Dry Gas Seal in a 1500 HP Turbine Modification of GP Turbines for Fast Start without Slow Rolling How the GP Turbine Fast Startup Modification Works Dry Flexible Metal Coupling Upgrade with Split Spacer, for Short Coupled Turbines with Insufficient Length Coupling Spacers General Purpose Lube Oil System Upgrade for Self-Contained Bearing Housings to Eliminate Overheating & Bearing Failures Governor and Trip System Upgrade from Hydraulic to Electronic-Pneumatic Governor Requirements: Electronic Governor with Pneumatic Actuator & Pneumatic Trip System Governor and Trip System Requirements Overview of All-Electronic Trip and Overspeed Protection System Outboard Bearing Improved Flex Foot: Higher Turbine Reliability & Lower Vibration Results

9 Part III: MAINTENANCE BEST PRACTICES 10 Rotating Machinery Repair Best Practices World-Class Reliability Performance Should be the Goal of Every Repair Facility Cutting Corners = Unreliability The Importance of Alignment Alignment Tolerances [2] Alternative Alignment Guidelines Alignment Calculation Example Rotor Balance Static Unbalance Dynamic Unbalance Balancing Common Causes of Rotor Unbalance [3] Balancing Grades The Importance of Fit, Clearance & Tolerance Fits, Clearances and Tolerances [5] Tolerance Clearance Coupling Hub Fits Keyed Interference Fits [6] Keyless Interference Fits Closing Thoughts References 11 Procedures + Precision = Reliability 12 The Top 10 Behaviors of Precision-Maintenance Technicians 13 Optimizing Machinery Life Cycle Costs through Precision and Proactive Maintenance Precision Maintenance 101 Life-Extension Equations Worked Example Life Cycle Costs Justifying Precision Maintenance 14 Optimum Reference States for Precision Maintenance Conclusion 15 Writing Effective Machinery Work Order Requests

10 Part IV: ANALYZING FAILURES 16 Improving Machinery Reliability by Using Root Cause Failure Analysis Methods Introduction What Is a Root Cause Failure Analysis? Root Cause Failure Analysis Example #1: Ill-Advised Bearing Replacement Root Cause Failure Analysis Example #2: Reciprocating Compressor Rod Failure [1] RCFA Steps Closing Thoughts Appendix ANo Magic Allowed Appendix BAnalyzing Component Failure Mechanisms Common Mechanical Failure Modes Rolling Element Bearing Failure Characteristics [6] Tips for Analyzing Mechanical Seal Failures [7] Appendix CCommon Machinery Failure Modes [8] References 17 Investigation and Resolution of Repetitive Fractionator Bottom Pump Failures Introduction List of Additional Failure Inherent Causes to Be Rectified Key Shop and Field Pump Measurements Conclusion [1] Actual Findings Effect of Improvements on Pump Radial Shaft Vibration Reference 18 Reliability Improvements Made to 6000 KW Water Injection Pumps Experiencing Wear Ring Failures Summary Sequence of Events New Design Proposal of Eliminating Grub Screws or Flash Butt Welding Upgrade Options Detailed Analysis of Problem & Solution Related to All Pump Wear Rings Discussion on Reliability Improvements Added to Achieve High Reliability Manufacturing Errors: None Found User Maintenance Errors: None Found

11 About the Editor

12 About the Contributors

13 Index

14 Also of Interest

15 End User License Agreement

1 Chapter 1 Figure 1.1 Managing the risk associated with a site’s process machinery is a key... Figure 1.2 Machinery failure modes distributions. Figure 1.3 Machinery failure modes can be broken down into those that are readil... Figure 1.4 Centrifugal compressor operating limits. This compressor curve repres... Figure 1.5 Typical centrifugal compressor surge control system. Figure 1.6 Here is a typical predicted forced response plot. The upper plot is t... Figure 1.7 A set of safeguards are designed to prevent major events from occurri... Figure 1.8 Reciprocating gas compressor cylinders.