Table Of Content

t R U L E S O F THUM F O R M E C H A N I C A L liEH A manual of quick, accurate solutions to everyday mechanical engineering problems J. Edward Pope, Editor R U L E S O F THUMEI F O R M E C H A N I C A L E N G I N E E R S Gulf Publishing Company Houston, Texas RULES OF THUMB FOR MECHANICAL ENGINEERS Copyright 8 1997 by Gulf Publishing Company, Houston, Texas. All rights reserved. Printed in the United States of America. This book, or parts thereof, may not be reproduced in any form without permission of the publisher. 1 0 9 8 7 6 5 4 3 Gulf Publishing Company Book Division P.O. Box 2608 0 Houston, Texas 77252-2608 Library of Congress Cataloging-in-Publication Data Rules of thumb for mechanical engineers : a manual of quick, accurate solutions to everyday mechanical engineering problems / J. Edward Pope, editor ;i n collaboration with Andrew Brewington . . . [et al.]. p. cm. Includes bibliographical references and index. ISBN 0-88415-790-3 (acid-free paper) 1. Mechanical engineering-Handbooks, manuals, . etc. I. Pope, J. Edward, 1956- 11. Brewington, Andrew. TJ151.R84 1996 62 14-20 96-35973 CIP Printed on acid-free paper (=I. iv . 1: Fluids 1 Friction Factor and Darcy Equation ............................... 9 Losses in Pipe Fittings and Valves .................................. 10 Fluid Properties ........................................................ 2 Pipes in Series ................................................................. 10 pipes in Parallel .............................................................. 10 Density. Specific Volume. Specific Weight. ................................................. Specific Gravity. and Pressure .................................... 2 Open-Channel Flow 11 Surface Tension .............................................................. 2 Frictionless Open-Channel Flow .................................... 11 ......................................... Vapor Pressure ................................................................ 2 Laminar Open-Channel Flow 12 Gas and Liquid Viscosity ................................................ 3 Turbulent Open-Channel Flow ....................................... 12 Bulk Modulus ................................................................. 3 Hydraulic Jump ................................................................................................................ 12 Compressibility. .............................................................. 3 Fluid Measurements 13 Units and Dimensions ..................................................... 3 Pressure and Velocity Measurements ............................. 13 Fluid Statics .............................................................. 4 Flow Rate Measurement ................................................. 14 ........................... Manometers and Pressure Measurements ....................... 4 Hot-wire and Thin-Film Anemometry 14 Hydraulic Pressure on Surfaces ...................................... 4 Open-Channel Flow Measurements ............................... 15 Buoyancy ........................................................................ 5 Viscosity Me.a..s..u..r..e..m...e...n..t.s.. ................................................................................. ........ 15 ........................................................ Basic Equations 5 Other Topi CS 16 Continuity Eq~tio.n... .................................................... 5 Unsteady Flow, Surge, and Water Hammer .................... 16 Euler’s Equation ............................................................. 5 Boundary Layer Concepts .............................................. 16 Bernoulli’s Equation ....................................................... 6 Lift and Drag ................................................................... 16 Energy Equation ............................................................. 6 Oceanographic Flows ..................................................... 17 Momentum Equation ...................................................... 6 ................................... Moment-of-Momentum Equation 6 .............................. Advanced Fluid Flow Concepts 7 ..................................................... Dimensional Analysis and Similitude ............................ 7 Introduction......... 19 ................................................................ Nondimensional Parameters ........................................... 7 Conduction 19 Equivalen..t. .D...i.a..m...e..t.e..r.. .a..n..d.. .H...y..d..r..a.u...l.i.c.. .R..a..d...i.u..s.. .................. .......... 8 Single Wall Conduction. ................................................. 19 Pipe Flow 8 Composite Wall Conduction. .......................................... 21 V The Combined Heat Transfer Coefficient. ...................... 22 Diesel Cycle: Another Power Cycle ............................... 63 Critical Radius of Insulation ........................................... 22 Gas Power Cycles with Regeneration. ............................ 64 ................................................................. Convection 23 Dimensionless Numbers ................................................. 23 4: Mechanical Seals. 66 Correlations. .................................................................... 24 Typical Convection Coefficient Values .......................... 26 ....................... ................................................................... Basic Mechanical Seal Components 67 Radiation 26 ............................................................ Emissivity ....................................................................... 27 Sealing Points .............................. 67 View Factors ................................................................... 27 Mechanical Seal Classifications 68 ..................................................... Radiation Shields ............................................................ 29 Basic Seal Designs 68 ........................................... ......................................... Finite Element Analysis 29 Basic Seal Arrangements 72 ............................................ Boundary Conditions ...................................................... 29 Basic Design Principles 74 ........................................ 2D Analysis .................................................................... 30 Materials of Construction 77 ....................................... Transient Analysis .......................................................... 30 Desirable Design Features 79 Evaluating Results .................................................................................... ...... 3 1 Equipment Considerations. ..................................... 80 ....................... Heat Exchanger Classification 33 Calculating Seal Chamber Pressure 81 Types of Heat Exchangers .............................................. 33 ........................................................ Seal Flush Plans 82 Shell-and-Tube Exchangers ............................................ 36 ...................................... Integral Pumping Features 85 Tube Arrangements and Baffles ..................................... 38 ........................................ Shell Configurations ....................................................... 40 Seal System Heat Balan...c...e.. ...................................... 87 Miscellaneous Data ......................................................... 42 Flow Rate C...a..l..c..u...l.a..t..i.o...n... ......................................... 89 References 91 Flow Regimes and Pressure Drop in Two-Phase ........................................................ Heat Transfer 42 Flow Regimes ................................................................. 42 5: Pumps and Compressors. 92 Flow Maps ...................................................................... 46 Estimating Pressure Drop ............................................... 48 ~~ ~ ............................ Pump Fundamentals and Design 93 Pump and Head Terminology ......................................... 93 3: Thermodynamics. 51 Pump Design Parameters and Formulas ......................... 93 ...................................... Types of Pumps. .............................................................. 94 Thermodynamic Essentials 52 Centrifugal Pumps .......................................................... 95 Phases of a Pure Substance. ............................................ 52 Net Positive Suction Head (NPSH) and Cavitation. ....... 96 Thermodynamic Properties. ............................................ 53 Pumping Hydrocarbons and Other Fluids ...................... 96 Determining Properties. .................................................. 55 Recirculation. .................................................................. 97 Types of Systems ............................................................ 56 Pumping Power and Efficiency ...................................... 97 Types of Processes .......................................................... 56 Specific Speed of Pumps ................................................ 97 The Zeroth Law of Thermodynamics. ............................ 57 Pump Similitude ............................................................. 98 ................................ First Law of Thermodynamics 58 Performance Curves. ....................................................... 98 Work ................................................................................ 58 Series and Parallel Pumping ........................................... 99 Heat ................................................................................. 58 Design Guidelines. .......................................................... 100 First Law of Thermodynamics for Closed Systems ....... 58 Reciprocating Pumps ...................................................... 103 ............................................................. First Law of Thermodynamics for O.p...e..n... .S...y...s..t.e...m....s.. .......... 58 Compressors 110 Second Law of Thermodynamics 59 Definitions ...................................................................... 110 Reversible Processes and Cycles .................................... 59 Performance Calculations for Reciprocating Thermodynamic Temperature Scale ............................... 59 Compressors ............................................................... 111 Useful Expressions ......................................................... 59 Estimating Suction and Discharge Volume Bottle ........................................... Thermodynamic Cycles 60 Sizes for Pulsation Control for Reciprocating Basic Systems and Systems Integration ......................... 60 Compressors ............................................................... 114 Carnot Cycle ................................................................... 60 Compression Horsepower Determination. ...................... 117 Rankine Cycle: A Vapor Power Cycle. ........................... 61 Generalized Compressibility Factor ............................... 119 Reversed Rankine Cycle: A Vapor Refrigeration Cycle . 61 Centrifugal Compressor Performance Calculations ....... 120 Brayton Cycle: A Gas Turbine Cycle ............................. 62 Estimate HP Required to Compress Natural Gas ........... 123 Otto Cycle: A Power Cycle ............................................ 63 Estimate Engine Cooling Water Requirements .............. 124 vi ......................................................... Estimate Fuel Requirements for Internal Combustion Lubricant Selection 162 Engines ................................ ............................................. ....... ........................... ....... ........ .. .... 124 Lubrica.tin.g M ethods. ...................................................... 163 ................................................................... References " 12A Relubncahon 164 ............................... Cleaning. Preservation. and Storage 165 ................................................................... 6: Drivers. 125 Mounting 166 ........................................................................... Shafting 166 .................................................... ......................................................................... Housings 169 Motors: Efficiency 126 ............................................... Bearing Clearance. .......................................................... 172 Motors: Starter Sizes 127 ............................................ Seals ................................................................................ 174 Motors: Service Factor 127 ......................................................... ........................................ Sleeve Bearings 175 Motors: Useful Equations 128 ................................................................. ............................................. References 177 Motors: Relative Costs 128 ................................................ Motors: Overloading 129 ................................... 9 Pipina and Pressure Vessels. 178 Steam Wbines: Steam Rate 129 ...................................... Steam mrbines: Efficienc..y... .................................... 129 .................................................... Gas Wbines: Fuel Rates 130 Process Plant Pipe 179 .......................................... .................................................... Gas Engines: Fuel Rates 132 Definitions and Sizing 179 Gas Expanders: Available Energy .......................... 132 Pipe Specifications. ......................................................... 187 .................................................................... Storing Pipe 188 7: liearsJ33 Calculations to Use ........................................................................................... ..... 189 Transportation Pipe Lines 190 . ........................................ Steel Pipe Design ............................................................ 190 Ratios and Nomenclature 134 ............................................................ ................................. Gas Pipe Lines 190 Spur and Helical Gear Design 134 ........................................................ .................................................... Liquid pipe Lines ............................. 192 Bevel Gear Design .............................. 139 Pipe Line Condition Monitoring 195 Cylindrica..l. .W.....o..r..m.... .G....e...a..r.. .D....e..s..i.g..n... ....................... 141 Pig-based Monitoring Systems ....................................... 195 Materials 142 Coupons .......................................................................... 196 .......................................... s wof Gea r Qpes 143 Manual Investigation ...................................................... 196 ............................... ........................................................ Buying Gea..r.s... .a..n...d... .G....e..a...r.. .D...r...i.v..e...s. ........................ 144 Cathodic Protecti..o..n.. .................................................. 197 References 144 Pressure Vessels 206 Stress Analysis ................................................................ 206 Failures in Pressure Vessels ............................................ 207 8: Bearings. 145 ......................................................................... Loadings 208 ..................................................... stress ............................................................................... 209 Qpes of Bearings 146 ........................... procedure 1: General Vessel Formulas 213 .................................................................. Ball Bearings 146 Procedure 2: Stresses in Heads Due to Internal ............................................................... Roller Bearings 147 ....................................................................... Pressure 215 ............................................................... Standardization 149 .................................... Joint Efficiencies (ASME Code) 217 ......................................................................... Materials ......................................................... 151 Properties of Heads ......................................................... 218 Rating and Life 152 Volumes and Surface Areas of Vessel Sections .............. 220 ABMA Definitions ......................................................... 152 Maximum Length of Unstiffened Shells ........................ 221 Fatigue Life ..................................................................... 153 Useful Formulas for Vessels ........................................... 222 ................................................. Life Adjustment Factors ......................................... 154 Material Selection Guide ................................................ 224 Load and Speed Analysis 156 References. ...................................................................... 225 Equivalent Loads ............................................................ 156 Contact Stresses. ............................................................. 157 Preloading ....................................................................... 157 10: Tribology. 226 Special Loads .................................................................. 158 .............................................................. Effects of Sp..e..e..d.. ............................................................................................................... ...... 159 Introduction ................................................... 227 Lubrication 160 Contact Mechanics 227 General. ........................................................................... 160 Two-dimensional (Line) Hertz Contact of Cylinders ..... 227 Oils. ................................................................................. 161 Three-dimensional (Point) Hertz Contact. ...................... 229 Greases ............................................................................ 161 Effect of Friction on Contact Stress ................................ 232 vii ................................................... Yield and Shakedown Criteria for Contacts ................... 232 Mechanical Testing 284 ..................... ................................................................ Topography of Engineering Surfaces 233 Tensile Testing 284 Definition of Surface Roughness .................................... 233 Fatigue Testing. ............................................................... 285 Contact of Rough Surfaces ............................................. 234 Hardness Testing. ............................................................ 286 Life Fac..t.o...r.s.. ................................................................................................................................ .. 234 Creep an..d.. .S..t.r..e.s..s.. .R...u..p..t.u..r.e.. .T...e..s.t.i.n..g... ............................................................. 287 Friction 235 Forming 288 ........................................................................... ....................................................................... Wear 235 Casting 289 ............................................................... .............................................................. Lubrication 236 Case Studies 290 ................................................................. References 237 Failure Analysis .............................................................. 290 ........................................................................ Corrosion 291 ................................................................. References 292 11: Vibration. 238 Vibration D..e..f..i.n...i.t..i.o...n..s..... .T...e..r..m....i.n...o...l.o...g..y..... .a...n..d... .... 13: Stress and Strain. 294 Symbols 239 .......... ~ ~~ ~~ ~~ ......................... Solving the One Degree of Freedom System 243 ....... Fundamentals of Stress and Strain 295 Solving Multiple Degree of Freedom Systems 245 ..................................................................... ..... Introduction 295 Vibration Measurements .a...n...d... .I..n...s...t..r..u...m.....e..n....t.a...t ion 246 Definitions4tress and Strain ....................................... 295 Table A: Spring Stiffness 250 Equilibrium. .................................................................... 297 .. Table B: Natural Frequencies of Simple Systems 251 Compatibility. ................................................................. 297 Table C: Longitudinal and Torsional Vibration of Saint-Venant’s Principle. ................................................. 297 ..................................................... .................................................................. Uniform Beams 252 Superposition 298 Table D: Bending (Transverse) Vibration of Plane Stress/Plane Strain ................................................ 298 Uniform Beams ..................................................... 253 Thermal Stresses ......................................................................................................... ... 298 Table E: Natural Frequencies of Multiple DOF Stress Concentrations 299 .................................................................. .............. Systems 254 Determination of Stress Concentration Facto..r.s.. ............ 300 .......... Design Criteria for Structural Analysis 305 Table F: Planetary Gear Mesh Frequencies 255 ....................... General Guidelines for Effective Criteria 305 Table G: Rolling Element Bearing Frequencies ......................... Strength Design Factors. ................................................. 305 and Bearing Defect Frequencies 256 ........................................................... Beam Analysis 306 Table H: Gene.r.a...l. .V....i.b...r..a..t..i.o...n... .D....i.a...g..n...o...s..t.i..c.. ....... Limitations of General Beam Bending Equations .......... 307 Frequenc..i.e..s.. .......................................................... 257 Short Beams .................................................................... 307 References 258 Plastic Bending ............................................................... 307 ............................................................................ Torsion 308 ........................................................ 12: Materials. 259 Pressure Vessels 309 .................................................... Thin-walled Cylinders 309 .................................................. .................................................. Classe.s. o f M...a..f..e..r..i.a..l..s.. ............................................... 260 Thick-walled Cylinders .................................. 309 Defrrut.o...n..s.. ................................................................ 260 Press Fits Between C.y...l..i.n...d...e..r..s.. .............................. 310 Metals 262 Rotating Equipment 310 Steels. .............................................................................. 262 Rotating Disks ................................................................ 310 Tool Steels ...................................................................... 264 Rotating Shafts. ................................................................................................................... ..... 313 Cast Iron .......................................................................... 265 Flange Analysis 315 Stainless Steels. ............................................................... 266 Flush Flanges .................................................................. 315 Superalloys ..................................................................... 268 Undercut Flanges ........................................................................................................ ... 316 Aluminum Alloys ........................................................... 269 Mechanical Fasteners 316 Joining. ............................................................................ 270 Threaded Fasteners ......................................................... 317 Coatings .......................................................................... 273 Pins ................................................................................. 318 Corrosion ........................................................................ 276 Rivets ............................................................................................................... ...... 318 Powder Metallurgy ......................................................... 279 Welded and Brazed Joints 319 .................................................................... .......................................................... PolJTmer s 281 Creep Rupture 320 ................................................... ........................................... cera^^................. 284 Finite Element Analysis 320 viii ................................................. Overview. ........................................................................ 321 Strain Measurement 362 The Elements .................................................................. 321 The Electrical Resistance Strain Gauge. ......................... 363 Modeling Techniques. ..................................................... 322 Electrical Resistance Strain Gauge Data Acquisition. .... 364 .......... Advantages and Limitations of FEM .............................. 323 Liquid Level and Fluid Flow Measurement 366 Centroids and Moments of Inertia for Common Liquid Level Measurement ............................................. 366 .................................................................... Shapes 324 Fluid Flow Measurement ................................................ 368 ................................................................. Beams: Shear. Moment, and &flection Formulas References 370 .............................. for Common End Conditions 325 ................................................................. References 328 16: Engineering Economics. 372 .... 14: Fatigue. 329 Time Value of Money: Concepts and Formulas 373 Simple Interest vs .C ompound Interest. .......................... 373 .............................................................. Introduction 330 Nominal Interest Rate vs . Effective Annual ....................................................... Stages of Fatigue 330 Inkrest Rate ................................................................ 374 ................................. Present Value of a Single Cash Flow To Be Received Design Approaches to Fatigue 331 ......................................... in the Future ................................................................ 374 Crack Initiation Analysis 331 Residual Stresses ............................................................ 332 Future Value of a Single Investment ............................... 375 Notches ........................................................................... 332 The Importance of Cash Flow Diagrams ........................ 375 Real World Loadings ...................................................... 335 Analyzing and Valuing InvestmenBRrojects with Temperature Interpolation .............................................. 337 Multiple or Irregular Cash Flows ............................... 375 Material Scatter. .............................................................. 338 Perpetuities ..................................................................... 376 Estimating Fatigue Properties. ........................................ 338 Future Value of a Periodic Series of Investments ........... 377 .................................... Annuities, Loans, and Leases ......................................... 377 Crack Propagation Analysis 338 Gradients (PayoutsPayments with Constant K-The Stress Intensity Factor ........................................................................... 339 Growth Rates) ............................................................. 378 Crack Propagation Calculations 342 Analyzing Complex Investments and Creep Crack Growth .................................................................................................... . 344 Cash Flow Problems ................................................... 379 Inspection Techniques 345 Decision and Evaluation Criteria for Investments Fluorescent Penetrant Inspection (PI) .......................... 345 .......................................... and Financial Projects 380 Magnetic Particle Inspection (MPI). ............................... 345 .................................................................... Payback Method ............................................................. 380 Radiography 345 Ultrasonic Inspection ...................................................... 346 Accounting Rate of Return (ROR) Method .................... 381 Eddy-current Inspection. ................................................. 347 Internal Rate of Return (IRR) Method. ........................... 382 Evaluation of Failed Parts ............................................... 347 Net Present Value (N..P..V....). .M....e..t..h..o..d... ........................................................ ..... 383 .............................................. Sensitivity Analysis 384 Nonmetallic Materials 348 .......................................................... Decision 'he Analysis of Investments and Fatig.u.e T ~ ~ g 349 ................................................. .......................................................... Financial Projects 385 Liabrllty Issues 350 ....................................... ................................................................. Accounting Fundamentals 389 References 350 ................ References and Recommended Reading 393 15: Instrumentation. 352 Appendix. 394 .............................................................. Introduction 353 ..................................... .................................................. Temperature Measurement 354 Conversion Factors 395 .............................................. .................................... Fluid Temperature Measurement 354 SysternS of Basic Units 399 ......... Surface Temperature Measurement ................................ 358 Decimal Multiples and Fractions of SI units 399 ....................... Common Temperature Sensors ....................................... 358 Temperature Conversion Equations 399 ............................................. Pressure Measurement 359 Total Pressure Measurement ........................................... 360 Index, 400 StaticKavity Pressure Measurement .............................. 361 ix