Condition Monitoring, Troubleshooting and Reliability in Rotating Machinery

Robert X. Perez is a mechanical engineer with more than 40 years of rotating equipment experience in the petrochemical industry. He has worked in petroleum refineries, chemical facilities, and gas processing plants. He earned a BSME degree from Texas A&M University at College Station, an MSME degree from the University of Texas at Austin and holds a Texas PE license. Mr. Perez has written numerous technical articles for magazines and conferences proceedings and has authored five books and coauthored four books covering machinery reliability, including several books also available from Wiley-Scrivener.

• Preface xixAcknowledgements xxiPart 1: Condition Monitoring 11 An Introduction to Machinery Monitoring 3By Robert X. Perez2 Centrifugal Pump Monitoring, Troubleshooting and Diagnosis Using Vibration Technologies 15By William D. MarscherIntroduction 15Vibration Definitions 16How Vibration vs. Time Relates to a Vibration vs. Frequency “Spectrum” 18What are Reasons for Excess Vibration? 19Relationship of Vibration to Centrifugal Pump Acceptability and Reliability 20Vibration Standards, Informal and Formal: Intent and Basis 21Vibration Measurement Form 22Vibration Detection Sensors 25Accelerometers 26Proximity Probes 27Motion Magnified Video (aka Vibration Video Amplification) 28International Vibration Acceptance Standards 30Pump Components Playing Key Roles in Vibration Diagnostics 33Rotor Support by Bearings: Fluid Film Journal Bearings vs. Rolling Element Bearings 33Rotor Support by Seals: Annular Seal “Lomakin Effect” 35Couplings 38Bearing Housings and Attachment Bolts 39Pump Casing, Feet, and Foot Attachment Bolts 39Pump Pedestals, Baseplate, and Foundation 40Piping, Suction, and Discharge 40Pump Drivers 43Evaluating Causes of Excess Vibration: Excitation vs. Amplification 43Process of Resonant Amplification due to Coincidence of Excitation and Natural Frequencies 45Impact Test Method of Determining Natural Frequencies 46Specific Forces in Centrifugal Pumps 48Mechanical Excitation Forces 48Balance 48Misalignment 50Mechanical Forces Due to Dry Running Pump, Dry Running Seal, Overtightened Seal 52Hydraulic Forces and Blade Passing Frequency 52Hydraulic Vibration Forces Below Running Speed, Including Subsynchronous Whirl 54Detection of Effects of Cavitation 57Torsional Excitations 59Vibrations Particular to Various Centrifugal Pump Types 62Vertical Turbine Pump Evaluation 62Vertical Dry Pit Pump Vibration Issues 65Submersible Pump Vibration Issues 65End Suction Overhung Single Stage Pump Vibration Issues 66Between Bearing Double Suction Single Stage Pump Vibration Issues 66Horizontal Multistage Pump Vibration Issues 67Steps in Pump Evaluation through Vibration Monitoring 68Use of the Bode and Nyquist Plots to Confirm Natural Frequencies 70Operating Deflection Shapes (ODS) 71Conclusions 73Nomenclature 73References & Bibliography 74Acknowledgements 753 Proximity Probes are a Good Choice for Monitoring Critical Machinery with Fluid Film Bearings 77By Robert X. PerezProximity Probe Benefits 77Theory of Operation 78Runout Concerns 80Grounding and Noise 80Shaft Orbits 81General Machinery Monitoring Recommendations 82Final Thoughts 85References 864 Optimizing Lubrication and Lubricant Analysis 87By Jim Fitch and Bennett FitchIntroduction 87Optimum Reference State 88Lubrication Excellence and the Ascend Chart 91Bringing Awareness to Lubrication, Contamination, and Oil Analysis 94What You Might Not Know About Lubrication 94Machine Surface Interaction 94The Lubricant Film 95Film Strength 96Unlubricated Surface Interactions 96Friction and Wear Generation 96Mitigating Surface Interactions 97Physics and Chemistry 97Contamination: The Antagonist to Lubrication 98Contamination Control and Condition Monitoring is More Often about Training than Advanced Technology 98Contamination Control 99Don’t Leave It to Instinct 99Creating a Balance Between Exclusion and Removal 100Why Perform Oil Analysis 102Fluid Properties Analysis 102Contamination Analysis 103Wear Debris Analysis 103Achieving Oil Analysis Success by Looking Holistically 103Obtaining a Representative Oil Sample 105Select the Right Machines for Oil Analysis 105Clean and Correct Sampling Containers and Extraction Tools 105Correctly Located Sampling Ports 106Proper Sampling Frequency 107Proper and Consistent Sampling Procedures 107Forward Samples Immediately to the Laboratory 108Ensuring Reliable Testing 108Certified Training of Laboratory Technicians 108Optimized Selection of Tests 109Onsite Oil Analysis 109Determining the Optimum Course of Action 110Effective Organization of Analysis with Proper Trending 110Accurate Data Interpretation by the Laboratory 110Enhanced Data Interpretation by the End-User 111Take Corrective Action and Determine the Root Cause 112Continuous Improvement and Key Performance Indicator (KPI) 112Oil Analysis Tests 112Viscosity 113Acid Number and Base Number 113Ftir 114Elemental Analysis 114Particle Counting 114Moisture Analysis 115Interpreting Oil Analysis Reports 116Following the Data Trends 118Looking Back at the Past 123Inspection 2.0: Advances in Early Fault Detection Strategy 124Low-Hanging Fruit 124Inspection Frequency Trumps High Science 125Beware of Short P-F and Sudden-Death Failures 127Inspection Windows and Zones 128Inspection 2.0 is a Nurturing Strategy 129Final Tips to Help Error-Proof Your Lubrication Program 130References 1345 Troubleshooting Temperature Problems 135By Robert X. PerezTemperature Assessments 135How do Infrared Thermometers Work? 136Bearing Temperature Trending 137Rolling Element and Sleeve Bearing Temperature Guidelines 139Rule of Thumb for Rolling Element Bearings: 142Bearing Temperature Guidelines for Instrumented Hydrodynamic Bearings 142Recommended Guidelines for Babbitt Bearings 142Bearing Temperature Sensor Placement 143Sleeve Bearings 143Tilting Pad Journal (TPJ) Bearings-Load on Pad 144Tilting Pad Journal Bearings-Load between Pads 144Thrust Bearings-Tilting Pad 144General Temperature Probe Installation Guidelines 145Compressor Discharge Temperature Assessments 146Heat of Compression 146Types of Compression Processes 147Adiabatic Compression 148Polytropic Compression 152Polytropic Example 1: 154Polytropic Example 2: 154Why Compression Ratio Matters 155What Role It Plays in Compressor Design and Selection 155Compression Ratio versus Discharge Temperature 155Design Temperature Margin 158Design Tradeoffs 159Reciprocating Compressor Temperature Monitoring 160Valve Temperature Monitoring 162Temperature Monitoring Example 164Summary 165References 1656 Assessing Reciprocating Compressors and Engines 167By Robert X. PerezOverview of Reciprocating Compressors 169General Monitoring Guidelines for Reciprocating Compressors 174Impact Monitoring 177Rod Drop Monitoring 178Using Ultrasonics to Assess Reciprocating Machinery 178Mystery Reciprocating Compressor Knock 179Natural Gas Engines 181How Accurate are Rotating Equipment and Reciprocating Equipment Analyst Findings? 190References 1937 Managing Critical Machinery Vibration Data 195By Robert X. PerezBeware of False Positives and False Negatives 195Vibration Analysis Strategies 197Part 2: Troubleshooting 2018 Addressing Reciprocating Compressor Piping Vibration Problems: Design Ideas, Field Audit Tips, and Assessment Methods 203By Robert X. PerezPiping Restraints 205Pipe Clamping Systems 207Guidelines 207Preloading Clamp Bolts 209Piping Assessment Steps 210Small-Bore Piping 211Attaching Pipe Clamps to Structural Members 212The Ideal Pipe Clamp Installation 213Installation Examples 214Collecting and Assessing Piping Vibration 217Piping Analysis Steps 220Piping Vibration Examples 221Bolt Torque Tables 223Chapter Glossary 2249 Remember to Check the Rotational Speed When Encountering Process Machinery Flow Problems 227By Robert X. Perez10 Troubleshooters Need to be Well Versed in the Equipment They are Evaluating 233By Robert X. PerezWhat is the Difference Between Troubleshooting and Conducting a Failure Analysis? 236Equipment Details 237Performance Characteristics 238Centrifugal Compressors 238Reciprocating Compressors 239Basic Fluid Film Bearing Troubleshooting Tips 240Design Basis: Speed, Pressures, Flows 241System Design Details 243OEM Recommendations 244History 244Putting it All Together 24511 Precise Coupling Properties are Required to Accurately Predict Torsional Natural Frequencies 247By Robert X. PerezIntroduction 247Case Study 247Start-Up Issues 249Field Vibration Study 249Lesson Learned 252Final Thoughts 25312 Is Vibration Beating on Machinery a Problem? 255By Robert X. Perez and Andrew P. ConkeyWhat is Vibration Beating? 255Zoom FFT (Fast Fourier Transform) Analysis 257Electric Motor Zoom Analysis 258Field Case Study: “Beating” Effect Caused by Two Closely Spaced Mechanical Frequencies Observed on Two-Shaft, Gas Turbine Drive 259Background Information 260Vibration Response Analysis 261Investigation of System and Analysis 261Frequency Analysis 262Case Study Solution 263Case Study Conclusions and Lessons Learned 263Final Comments 263References 264Part 3: Reliability 26513 Using Standby Machinery to Improve Process Reliability 267By Robert X. PerezIntroduction 267Basic Reliability Theory 267Exercising Spared Machinery 273Alternating Twin, Non-Critical, Process Pumps 273Recommended Swapping Procedures for Critical Motors, Pumps, Blowers, Compressors, Generators, and Steam Turbines 274Recommended Swapping Procedures for Reciprocating Process Plant Machinery above 200 HP 275Raptor Modeling Software 276Modeling Examples 277Example 1: Unspared Compressor 278Example 2: Main and Spare Compressor Installation 279Example 3: Two out of Three (2oo3) Compressor Configuration 280The Cost of Redundancy 282Example 4: Cost of Unreliability 283Economics 284Justifying of a Spare Compressor 285Closing Thoughts 287References 28714 Gas Turbine Drivers: What Users Need to Know 289By Robert X. PerezOverview 289Theory of Operation 292How Does a Gas Turbine Work? 292Air Compressor 294Combustors 296Transition Pieces 297Expansion Turbine 298Turbine Section Challenges and Solutions 299Two Shaft Gas Turbine Construction Details 301Gas Producer 301Lower Pressure Power Turbine (LP) 301Typical Conditions Inside an Industrial Gas Turbine 303Effect of Atmospheric Conditions 304Gas Turbine Controls 305Protection 305Fuel and Fuel Treatment 306Gas Fuels 306Degradation and Water Washing 306Advanced Materials for Land Based Gas Turbines 307Blade Degradation 308Condition Monitoring Approaches 309Aerothermal Performance Analysis 309Vibration Analysis 310Transient Analysis 311Mechanical Transient Analysis 311Dynamic Pressure Analysis 312Lube Oil Debris Analysis 312Borescope Inspection 312Condition Monitoring as a System 313Gas Turbine Maintenance Inspections 313Standby Inspections 314Running Inspections 314Combustion Inspections 316Hot Gas Path Inspections 316Major Inspections 316Life Cycle Management 318Non-Destructive Testing (NDT) 320Spare Parts 321Final Words of Advice 322References 32315 Reliability Improvement Ideas for Integrally Geared Plant Air Compressors 325By Abdulrahman AlkhowaiterIntegrally Geared Plant Air Compression Packages 325Reliability Concerns 327Developing Enhancements for Air Compressor Reliability and Performance 330Reliability Improvement Program to Achieve Reliability and Eliminate Frequent Failures 330Reliability Improvements (based on 2008 Report) Made to Five (5) 850 HP Air Compressor Failures by Engineering and Maintenance: 33116 Failure Analysis & Design Evaluation of a 500 KW Regeneration Gas Blower 341By Abdulrahman AlkhowaiterIntroduction 341Detail Design Analysis 343Conclusion 349Needed Action by Repair Shop 350Action Required by Refinery 35017 Operating Centrifugal Pumps with Variable Frequency Drives in Static Head Applications 353By Robert X. PerezVFD Advantages 354Static Head Systems 356Recommended Startup Sequence 359Final Thoughts 362References 36218 Estimating Reciprocating Compressor Gas Flows 363By Robert X. PerezSwept Volume 364Clearance Volume 365Volumetric Efficiency 365Flow Calculation Example 370Factors Affecting Compressor Flow 371Final Words 37119 Use Your Historical Records to Better Manage Time Dependent Machinery Failure Modes 373By Robert X. PerezPart 4: Professional Development 37920 Soft Skills and Habits that All Machinery Professionals Need to Develop 381By Robert X. PerezAsking Probing Questions 383Listening More Carefully 384Observing 385Continuously Learning 386Praising 387Teaching 388Closing Remarks 39021 Developing Rotating Machinery Competency 391By Robert X. PerezPart I: Preparing Students to Work with Rotating Machinery 391Rotating Machinery Related Job Functions 391Part II: Steps to Improving Rotating Machinery Competency: Study-Practice-Share 396About the Editor 403About the Contributors 405Index 409