Maintenance, Reliability and Troubleshooting in Rotating Machinery

Description

Rotating machinery represents a broad category of equipment, which includes pumps, compressors, fans, gas turbines, electric motors, internal combustion engines, and other equipment, that are critical to the efficient operation of process facilities around the world. These machines must be designed to move gases and liquids safely, reliably, and in an environmentally friendly manner. To fully understand rotating machinery, owners must be familiar with their associated technologies, such as machine design, lubrication, fluid dynamics, thermodynamics, rotordynamics, vibration analysis, condition monitoring, maintenance practices, reliability theory, and other topics. The goal of the “Advances in Rotating Machinery” book series is to provide industry practitioners a time-savings means of learning about the most up-to-date rotating machinery ideas and best practices. This three-book series will cover industry-relevant topics, such as design assessments, modeling, reliability improvements, maintenance methods and best practices, reliability audits, data collection, data analysis, condition monitoring, and more. Volume one began the series by focusing on design and analysis. Volume two continues the series by covering important machinery reliability concepts and offering practical reliability improvement ideas. Best-in-class production facilities require exceptional machinery reliability performance. In this volume, exceptional machinery reliability is defined as the ability of critical rotating machines to consistently perform as designed, without degradation or failure, until their next scheduled overhaul. Readers will find this volume chock-full of practical ideas they can use to improve the reliability and efficiency of their machinery. Cover Half-Title Page Series Page Title Page Copyright Page Dedication Contents Preface Acknowledgements 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 Background History Safeguards Conclusion Closing Remarks 2 Useful Analysis Tools for Tracking Machinery Reliability Commonly Used Metrics for Spared Machinery: Mean Time to Repair (MTTR) Mean Time Between Failure (MTBF) Additional Reliability Assessment Tools for Spared Machines Pareto Charts & 80-20 Rule 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 Some Definitions Related to Spare Parts 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 Part II: DESIGN AUDITS AND IMPROVEMENT IDEAS 6 Evaluating Centrifugal Pumps in Petrochemical Applications Crude Oil Processing Desalting Crude Oil Distillation Properties of Distillation and Fractionator Fractions Defining NPSHr, NPSH3, and NPSH Margin Natural Gas Processing: NGL Processing Centrifugal Pump Design Audits Design Standards The Materials of Construction The Hydraulic Fit The NPSH Margin 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 Pumps Handling a Liquid with Varying Densities Slurry Pumps FCC Slurry Pumps Bottoms Pumps Hot Pumps with Galling Tendencies Starting Hot Pumps High Temperature Concerns Gaskets 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 Reducing Potential Leak Points Simplifying Operation and Maintenance Building Better Seal Support Systems Common Mechanical Sealing Design Challenges Sealing Light Hydrocarbon Liquids Sealing Hazardous Organic NESHAP Liquids Buffer Gas Absorption Excessive Solids Seal Cooler Issues in Hot Applications Piping Plan 21 Advantages Disadvantages Piping Plan 23 Advantages Disadvantages Common Considerations for Flush Plans General Seal Piping Plan Recommendations Ways to Improve Seal Reliability Performance Seal Failure Analysis 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 Steam Turbine Leaks Bearing and Lubrication Failures Governor Failures and Sticking T&T Valves 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 SelfContained 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 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 Alternative Alignment Guidelines Alignment Calculation Example Rotor Balance Imperial Units Metric Units Static Unbalance Dynamic Unbalance Balancing Common Causes of Rotor Unbalance Balancing Grades The Importance of Fit, Clearance & Tolerance Fits, Clearances and Tolerances Tolerance Clearance Coupling Hub Fits Keyed Interference Fits Keyless Interference Fits Effects of Excessive Looseness Rotating Element Looseness Effects of Internal Looseness Structural Looseness As Found and As Left Measurements Closing Thoughts References 11 Procedures + Precision = Reliability 12 The Top 10 Behaviors of PrecisionMaintenance Technicians 13 Optimizing Machinery Life Cycle Costs through Precision and Proactive Maintenance Precision Maintenance 101 Life-Extension Equations Worked Example Life Cycle Costs Considering Energy Consumption Life Cycle Inventory Analysis Justifying Precision Maintenance Estimating the Benefits Now for the Cost-Benefit Analysis 14 Optimum Reference States for Precision Maintenance Fasteners Lubrication Alignment Balance Flab Management Conclusion 15 Writing Effective Machinery Work Order Requests 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 History Corrective Measures Comments Root Cause Failure Analysis Example #2: Reciprocating Compressor Rod Failure Background Physical root cause Latent root causes Comments RCFA Steps Step 1: Define the Problem Step 2: Gather Data/Evidence Identifying the Physical Root Cause of the Primary Failure Fatigue Example: Fin-Fan Cooler Shaft Failures Preserving Machine Data Step 3: Ask Why and Identify the Causal Relationships Associated with the Defined Problem Causal Chains Bearing Failure Sequence of Events with Descriptions Five Why RCFA Example Cause Mapping Cause Map Example #2 Single Root Cause versus Multiple Causes Cause Mapping Steps Inhibitors to Effective Problem Solving When Is a Root Cause Failure Analysis Justified? RCFA Levels Closing Thoughts Appendix A No Magic Allowed Identifying Sequence of Events and Causal Chains 5-Why Method of Investigation Advice on Failure Sequences Appendix B Analyzing Component Failure Mechanisms Common Mechanical Failure Modes Foreign Object Damage (FOD) Stress Corrosion Cracking Erosion Cavitation Hydrogen Embrittlement Galling Fretting Hot Corrosion (Gas Turbines) Common Hydrodynamic Bearing Failure Modes Rolling Element Bearing Failure Characteristics Tips for Analyzing Mechanical Seal Failures Common Seal Failure Modes Appendix C Common Machinery Failure Modes Pluggage Erosive Wear Fatigue Compressor Blade Fatigue Example Hydrodynamic Bearing Failure Examples Rubbing Unique Failure Modes 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 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 Example: Wear ring ID = 8.0 inches. Apply Taper Fit Principle Upgrade Options Detailed Analysis of Problem & Solution Related to All Pump Wear Rings Discussion on Reliability Improvements Added to Achieve High Reliability The Five Root Causes of Machinery Failure Design Errors Manufacturing Errors: None Found User Specification Errors User Maintenance Errors: None Found About the Editor About the Contributors Index Also of Interest