Introduction to the Design and Behavior of Bolted Joints Fourth Edition Non Gasketed Joints Mechanical Engineering By John H Bickford

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Introduction to the Design and Behavior of Bolted Joints Fourth Edition Non Gasketed Joints Mechanical Engineering By John H Bickford

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Table of Contents

Preface to the Fourth Edition…………………………………………………………………………………xxix
Acknowledgments for Volume 1 of the Fourth Edition ……………………………………………….xxxi
Preface to the Third Edition………………………………………………………………………………… xxxiii
Preface to the Second Edition ………………………………………………………………………………. xxxv
Preface to the First Edition ………………………………………………………………………………… xxxvii
Acknowledgments for the First Three Editions …………………………………………………………….xli
Editor………………………………………………………………………………………………………………….xliii
Abstract ……………………………………………………………………………………………………………….xlv
Chapter 1
Basic Concepts ………………………………………………………………………………………………………..1
1.1 Two Types of Bolted Joints ……………………………………………………………………………….1
1.2 Bolt’s Job ………………………………………………………………………………………………………..1
1.2.1 Tensile Joints …………………………………………………………………………………………1
1.2.2 Shear Joints …………………………………………………………………………………………..3
1.3 The Challenge ………………………………………………………………………………………………….3
1.3.1 Assembly Process……………………………………………………………………………………4
1.3.2 In-Service Behavior…………………………………………………………………………………5
1.3.2.1 Joints Loaded in Tension …………………………………………………………… 5
1.3.2.2 Shear Joints ……………………………………………………………………………… 5
1.4 Failure Modes………………………………………………………………………………………………….6
1.5 Design …………………………………………………………………………………………………………….7
1.5.1 In General……………………………………………………………………………………………..7
1.5.2 Specific Goals of the Designer………………………………………………………………….7
1.6 Layout of the Book…………………………………………………………………………………………..8
Exercises …………………………………………………………………………………………………………………8
Chapter 2
Materials ………………………………………………………………………………………………………………11
2.1 Properties That Affect the Clamping Force………………………………………………………..11
2.1.1 Magnitude of the Clamping Force ………………………………………………………….11
2.1.2 Stability of the Clamping Force ……………………………………………………………..12
2.1.2.1 Thermal Expansion or Contraction …………………………………………… 12
2.1.2.2 Corrosion ………………………………………………………………………………. 12
2.1.2.3 Fatigue Rupture ……………………………………………………………………… 12
2.1.2.4 Loss of Strength with Temperature……………………………………………. 12
2.1.2.5 Loss of Clamping Force with Temperature ………………………………… 13
2.1.2.6 Elastic Stiffness of the Parts ……………………………………………………… 13
2.1.2.7 Change in Stiffness with Temperature…………………………………….. 13
2.1.2.8 Brittle Fracture ……………………………………………………………………. 13
2.1.3 Miscellaneous Properties…………………………………………………………………….13
2.2 Fastener Standards………………………………………………………………………………………..14
2.3 Selecting an Appropriate Standard ………………………………………………………………….14
2.4 Bolting Materials…………………………………………………………………………………………..16
2.5 Tensile Strength of Bolting Materials ………………………………………………………………16
2.5.1 General Purpose=Automotive Group……………………………………………………17
2.5.2 Structural Steel Group……………………………………………………………………….17
2.5.3 Petrochemical=Power Group……………………………………………………………….17
2.5.4 Metric Group……………………………………………………………………………………17
2.5.5 Extreme-Temperature Materials ………………………………………………………….18
2.5.5.1 American Society for Testing and Materials (ASTM)
F2281 Materials…………………………………………………………………… 18
2.5.5.2 Traditional High-Temperature Materials ………………………………… 18
2.5.6 Corrosion-Resistant Group…………………………………………………………………19
2.5.7 Two New ASTM Bolting Standards…………………………………………………….19
2.5.7.1 Room Temperature Strengths of ASTM F2281
and F2282 Materials…………………………………………………………….. 20
2.6 Metric Fasteners……………………………………………………………………………………………20
2.7 Equivalent Materials ……………………………………………………………………………………..21
2.8 Some Comments on the Strength of Bolting Materials ………………………………………21
2.8.1 In General ………………………………………………………………………………………..21
2.8.2 Shear Strength…………………………………………………………………………………..21
2.8.3 Bearing Yield Strength……………………………………………………………………….23
2.8.4 Hardness versus Strength……………………………………………………………………23
2.9 Nut Selection………………………………………………………………………………………………..24
2.10 Effects of Temperature on Material Properties………………………………………………….26
2.10.1 Thermal Expansion ……………………………………………………………………………27
2.10.2 Miscellaneous Temperature Problems…………………………………………………..31
2.11 Other Material Factors to Consider…………………………………………………………………32
2.11.1 Fatigue Properties ……………………………………………………………………………..32
2.11.2 Corrosion …………………………………………………………………………………………32
2.11.3 Miscellaneous Considerations ……………………………………………………………..32
2.12 Joint Materials ……………………………………………………………………………………………..32
Exercises ……………………………………………………………………………………………………………….35
References and Bibliography……………………………………………………………………………………35
Chapter 3
Stress and Strength Considerations…………………………………………………………………………..39
3.1 Types of Strength………………………………………………………………………………………….39
3.1.1 Tensile Strength ………………………………………………………………………………..39
3.1.2 Thread-Stripping Strength ………………………………………………………………….39
3.1.3 Shear Strength…………………………………………………………………………………..40
3.1.4 Brittle Fracture Strength…………………………………………………………………….40
3.1.5 Strengths at High and Low Temperatures …………………………………………….40
3.1.6 Fatigue Strength………………………………………………………………………………..40
3.1.7 Stress Corrosion Cracking Strength……………………………………………………..40
3.2 Bolt in Tension……………………………………………………………………………………………..41
3.2.1 Elastic Curves for Bolts in Tension………………………………………………………41
3.2.2 Elastic Curves under Repeated Loading……………………………………………….42
3.2.3 Stress Distribution under Tensile Load ………………………………………………..42
3.2.4 Stress Concentrations…………………………………………………………………………43
3.2.5 Magnitude of Tensile Stress ………………………………………………………………..43
3.2.6 Stress in the Nut ……………………………………………………………………………….45
3.3 Strength of a Bolt………………………………………………………………………………………….48
3.3.1 Proof Strength…………………………………………………………………………………..48
3.3.2 Tensile Stress Area…………………………………………………………………………….49
3.3.3 Other Stress Area Equations……………………………………………………………….50
3.3.4 Stress Areas—Metric Threads……………………………………………………………..51
3.3.5 Strength of the Bolt under Static Loads ……………………………………………….53
3.4 Strength of the Joint ……………………………………………………………………………………..54
3.4.1 Contact Stress between Fastener and Joint……………………………………………54
3.4.2 Stresses within and between the Joint Members …………………………………….56
3.4.3 Static Failure of the Joint …………………………………………………………………..56
3.5 Other Types of Load on a Bolt……………………………………………………………………….57
3.5.1 Strength under Combined Loads …………………………………………………………59
Exercises and Problems …………………………………………………………………………………………..59
References and Bibliography……………………………………………………………………………………59
Chapter 4
Threads and Their Strength …………………………………………………………………………………….61
4.1 Thread Forms ………………………………………………………………………………………………61
4.1.1 Thread Forms in General …………………………………………………………………..61
4.1.2 Inch Series Thread Forms…………………………………………………………………..61
4.1.3 Metric Thread Forms…………………………………………………………………………63
4.2 Thread Series………………………………………………………………………………………………..63
4.3 Thread Allowance, Tolerance, and Class………………………………………………………….64
4.3.1 Inch Series Threads……………………………………………………………………………64
4.3.1.1 Allowance …………………………………………………………………………… 64
4.3.1.2 Tolerance ……………………………………………………………………………. 64
4.3.1.3 Class ………………………………………………………………………………….. 64
4.3.2 Metric Threads………………………………………………………………………………….65
4.3.2.1 Tolerance Position (the Allowance)………………………………………… 66
4.3.2.2 Tolerance Grade (the Tolerance)……………………………………………. 66
4.3.2.3 Tolerance Class (the Class)……………………………………………………. 66
4.3.3 Inch Series and Metric Thread Classes, Compared ………………………………..66
4.3.4 Coating Allowances …………………………………………………………………………..67
4.3.5 Tolerances for Abnormal Lengths of Engagement …………………………………67
4.4 Inspection Levels…………………………………………………………………………………………..68
4.5 Thread Nomenclature ……………………………………………………………………………………69
4.5.1 Inch Series………………………………………………………………………………………..69
4.5.2 Metric Thread …………………………………………………………………………………..69
4.6 Coarse- versus Fine- versus Constant-Pitch Threads ………………………………………….70
4.6.1 Coarse-Pitch Threads…………………………………………………………………………70
4.6.2 Fine-Pitch Threads…………………………………………………………………………….70
4.6.3 Constant-Pitch Threads ……………………………………………………………………..70
4.6.4 Miscellaneous Factors Affecting Choice ……………………………………………….70
4.7 The Strength of Threads ………………………………………………………………………………..71
4.7.1 Basic Considerations ………………………………………………………………………….71
4.7.2 Thread Strength Equations …………………………………………………………………71
4.7.3 Thread Strength Computations When Le ¼ D………………………………………72
4.7.4 Basic Procedure—An Example ……………………………………………………………73
4.7.5 Thread Strength Calculations When Le 6¼D………………………………………….73
4.7.6 Other Stress Area Formulas………………………………………………………………..74
4.8 What Happens to Thread Form under Load? …………………………………………………..76
4.9 Things That Modify the Static Strength of Threads …………………………………………..76
4.9.1 Common Factors ………………………………………………………………………………76
4.9.2 Which Is Usually Stronger—Nut or Bolt? …………………………………………….79
4.9.3 Tables of Tensile Stress and Shear Areas………………………………………………79
4.10 Other Factors Affecting Strength…………………………………………………………………….81
4.10.1 Pitch Diameter ………………………………………………………………………………….81
4.10.2 Other Thread Parameters……………………………………………………………………81
Exercises and Problems …………………………………………………………………………………………..82
References and Bibliography……………………………………………………………………………………82
Chapter 5
Stiffness and Strain Considerations…………………………………………………………………………..85
5.1 Bolt Deflection……………………………………………………………………………………………..85
5.1.1 Basic Concepts ………………………………………………………………………………….85
5.1.2 Change in Length of the Bolt ……………………………………………………………..87
5.1.2.1 Effective Length…………………………………………………………………… 87
5.1.2.2 Cross-Sectional Areas of the Bolt…………………………………………… 89
5.1.3 Computing Change in Length of the Bolt …………………………………………….89
5.2 Bolt Stiffness Calculations ……………………………………………………………………………..90
5.2.1 Basic Concepts ………………………………………………………………………………….90
5.2.2 Example …………………………………………………………………………………………..90
5.2.3 Actual versus Computed Stretch and Stiffness ………………………………………92
5.2.4 Stiffness of Bolt–Nut–Washer System ………………………………………………….92
5.2.5 Alternative Expression for Bolt Stiffness ………………………………………………92
5.2.6 Energy Stored in the Bolt …………………………………………………………………..93
5.3 The Joint ……………………………………………………………………………………………………..94
5.3.1 Basic Concepts ………………………………………………………………………………….94
5.3.2 Computing Joint Stiffness …………………………………………………………………..95
5.3.2.1 Stiffness of Concentric Joints ………………………………………………… 96
5.3.2.2 Stiffness of Eccentric Joints …………………………………………………… 97
5.3.3 Stiffness in Practice ………………………………………………………………………….100
5.3.3.1 A Quick Way to Estimate the Stiffness of Non-Gasketed
Steel Joints………………………………………………………………………… 100
5.4 Gasketed Joints …………………………………………………………………………………………..101
5.5 An Alternate Way to Compute Joint Stiffness ………………………………………………..103
5.6 Joint Stiffness Ratio or Load Factor ……………………………………………………………..104
5.7 Stiffness—Some Design Goals ………………………………………………………………………104
5.7.1 Energy Stored in the Joint Members ………………………………………………….104
5.7.2 Relationship between Stiffness and Stored Energy ……………………………….105
5.7.3 Stiffness Ratio…………………………………………………………………………………106
Exercises and Problems …………………………………………………………………………………………106
References …………………………………………………………………………………………………………..107
Chapter 6
Introduction to Assembly………………………………………………………………………………………109
6.1 Initial versus Residual Preload ……………………………………………………………………….109
6.2 Starting the Assembly Process ………………………………………………………………………..110
6.2.1 Assembling the Parts …………………………………………………………………………..110
6.2.2 Tightening the First Bolt ……………………………………………………………………..110
6.3 Bolt Preload versus Clamping Force on the Joint ……………………………………………..114
6.3.1 Effects of Hole Interference………………………………………………………………….114
6.3.2 Resistance from Joint Members ……………………………………………………………116
6.4 Continuing the Snugging Pass ………………………………………………………………………..119
6.5 Short-Term Relaxation of Individual Bolts ………………………………………………………119
6.5.1 Sources of Short-Term Relaxation ……………………………………………………….. 119
6.5.1.1 Poor Thread Engagement ………………………………………………………. 120
6.5.1.2 Thread Engagement Too Short……………………………………………….. 120
6.5.1.3 Soft Parts……………………………………………………………………………… 121
6.5.1.4 Bending ……………………………………………………………………………….. 121
6.5.1.5 Nonperpendicular Nuts or Bolt Heads …………………………………….. 121
6.5.1.6 Fillets or Undersized Holes …………………………………………………….. 121
6.5.1.7 Oversized Holes…………………………………………………………………….. 121
6.5.1.8 Conical Makeups ………………………………………………………………….. 121
6.5.2 Factors Affecting Short-Term Relaxation ………………………………………………122
6.5.2.1 Bolt Length ………………………………………………………………………….. 123
6.5.2.2 Belleville Washers………………………………………………………………….. 123
6.5.2.3 Number of Joint Members……………………………………………………… 123
6.5.2.4 Tightening Speed…………………………………………………………………… 123
6.5.2.5 Simultaneous Tightening of Many Fasteners…………………………….. 124
6.5.2.6 Bent Joint Members ………………………………………………………………. 124
6.5.3 Amount of Relaxation to Expect…………………………………………………………..124
6.5.4 Torsional Relaxation …………………………………………………………………………..125
6.6 Elastic Interactions between Bolts …………………………………………………………………..127
6.7 The Assembly Process Reviewed …………………………………………………………………….132
6.8 Optimizing Assembly Results …………………………………………………………………………134
Exercises ……………………………………………………………………………………………………………..135
References …………………………………………………………………………………………………………..135
Chapter 7
Torque Control of Preload…………………………………………………………………………………….137
7.1 Importance of Correct Preload ……………………………………………………………………….137
7.1.1 Problems Created by Incorrect Preload………………………………………………….138
7.1.2 How Much Preload? ……………………………………………………………………………138
7.1.3 Factors That Affect the Working Loads on Bolts……………………………………139
7.2 Torque versus Preload—The Long-Form Equation ………………………………………….. 140
7.3 Things That Affect the Torque–Preload Relationship………………………………………..142
7.3.1 Variables That Affect Friction………………………………………………………………142
7.3.2 Geometric Variables ……………………………………………………………………………143
7.3.3 Strain Energy Losses …………………………………………………………………………..144
7.3.4 Prevailing Torque ……………………………………………………………………………….144
7.3.5 Weight Effect ……………………………………………………………………………………..144
7.3.6 Hole Interference ………………………………………………………………………………..145
7.3.7 Interference Fit Threads …………………………………………………………………….145
7.3.8 The Mechanic………………………………………………………………………………….145
7.3.9 Tool Accuracy…………………………………………………………………………………145
7.3.10 Miscellaneous Factors………………………………………………………………………145
7.4 Torque versus Preload—The Short-Form Equation…………………………………………146
7.5 Nut Factors………………………………………………………………………………………………..147
7.5.1 Some General Comments………………………………………………………………….147
7.5.2 Nut Factor Examples and Case Histories……………………………………………148
7.5.3 Coefficient of Friction versus Nut Factor……………………………………………151
7.6 Torque Control in Practice …………………………………………………………………………..151
7.6.1 What Torque Should I Use? ……………………………………………………………..151
7.6.2 Initial Preload Scatter ………………………………………………………………………152
7.6.3 Low Friction for Best Control …………………………………………………………..153
7.6.4 The Lines Aren’t Always Straight………………………………………………………153
7.6.5 Other Problems ……………………………………………………………………………….154
7.7 Some Tools for Torque Control ……………………………………………………………………155
7.7.1 Some Generalities ……………………………………………………………………………155
7.7.2 Reaction Forces Created by the Tool …………………………………………………157
7.7.2.1 Shear Loads Created by Torque Wrenches ……………………………. 157
7.7.2.2 Reaction Torques ………………………………………………………………. 158
7.7.3 In the Beginning—A Search for Accuracy…………………………………………..159
7.7.3.1 Manual Torque Wrenches …………………………………………………… 159
7.7.4 More Torque for Large Fasteners ……………………………………………………..160
7.7.4.1 Torque Multipliers and Geared Wrenches …………………………….. 160
7.7.4.2 Hydraulic Wrenches …………………………………………………………… 160
7.7.5 Toward Higher Speed ………………………………………………………………………160
7.7.5.1 Impact Wrenches ……………………………………………………………….. 161
7.7.5.2 Pulse Tools ……………………………………………………………………….. 161
7.7.5.3 Nut Runners……………………………………………………………………… 161
7.7.6 Add Torque Calibration or Torque Monitoring…………………………………..162
7.7.7 Add Torque Feedback for Still Better Control…………………………………….164
7.7.8 For More Information……………………………………………………………………..164
7.8 Fasteners That Limit Applied Torque ……………………………………………………………164
7.8.1 The Twist-Off Bolt…………………………………………………………………………..164
7.8.2 The Frangible Nut …………………………………………………………………………..165
7.9 Is Torque Control Any Good?………………………………………………………………………166
7.10 Testing Tools………………………………………………………………………………………………166
7.11 The Influence of Torque Control on Joint Design……………………………………………167
7.12 Using Torque to Disassemble a Joint …………………………………………………………….168
Exercises and Problems …………………………………………………………………………………………169
References and Bibliography………………………………………………………………………………….169
Chapter 8
Torque and Turn Control ……………………………………………………………………………………..173
8.1 Basic Concepts of Turn Control ……………………………………………………………………173
8.2 Turn versus Preload …………………………………………………………………………………….175
8.2.1 Common Turn–Preload Relationship …………………………………………………175
8.2.2 Other Turn–Preload Curves………………………………………………………………176
8.2.2.1 Sheet Metal Joint……………………………………………………………….. 176
8.2.2.2 Gasketed Joint …………………………………………………………………… 177
8.3 Friction Effects……………………………………………………………………………………………177
8.4 Torque and Turn in Theory………………………………………………………………………….179
8.4.1 Torque, Turn, and Energy ………………………………………………………………….179
8.4.2 Torque–Turn–Preload Cube ……………………………………………………………….179
8.4.3 The Broader View……………………………………………………………………………..179
8.5 Turn-of-Nut Control……………………………………………………………………………………181
8.5.1 The Theory ………………………………………………………………………………………181
8.5.2 The Practice ……………………………………………………………………………………..182
8.5.2.1 Structural Steel ……………………………………………………………………. 182
8.5.2.2 Turn-of-Nut Procedure in Production Operations ……………………. 183
8.5.2.3 Turn-of-Nut Procedure in Aerospace Assembly ………………………. 183
8.6 Production Assembly Problems …………………………………………………………………….184
8.7 Popular Control Strategies……………………………………………………………………………186
8.7.1 Torque–Angle Window Control ………………………………………………………….186
8.7.2 Torque–Time Window Control …………………………………………………………..187
8.7.3 Hesitation and Pulse Tightening………………………………………………………….187
8.7.4 Yield Control ……………………………………………………………………………………188
8.7.5 Turn-of-Nut Control …………………………………………………………………………190
8.7.6 Prevailing Torque Control ………………………………………………………………….191
8.7.7 Plus—Permanent Records ………………………………………………………………….191
8.7.8 Meanwhile, Out in the Field ……………………………………………………………….191
8.8 Monitoring the Results ………………………………………………………………………………..192
8.9 Problems Reduced by Torque–Angle Control …………………………………………………193
8.10 How to Get the Most Out of Torque–Angle Control……………………………………….193
Exercises and Problems …………………………………………………………………………………………194
Bibliography and References………………………………………………………………………………….194
Chapter 9
Other Ways to Control Preload ……………………………………………………………………………..197
9.1 Stretch Control: The Concept ……………………………………………………………………….197
9.2 Problems of Stretch Control …………………………………………………………………………198
9.2.1 Dimensional Variations ……………………………………………………………………..198
9.2.2 Change in Temperature ……………………………………………………………………..199
9.2.3 Plastic Deformation of the Bolt…………………………………………………………..199
9.2.4 Bending and Nonperpendicular Surfaces………………………………………………199
9.2.5 Grip Length ……………………………………………………………………………………..199
9.3 Stretch Measurement Techniques ………………………………………………………………….199
9.3.1 Micrometer Measurements …………………………………………………………………199
9.3.1.1 Irregular Measurement Surfaces…………………………………………….. 199
9.3.1.2 Operator Feel ……………………………………………………………………… 200
9.3.1.3 Measurement Accuracy Required ………………………………………….. 200
9.3.1.4 Depth Micrometers ……………………………………………………………… 200
9.3.2 Other Techniques………………………………………………………………………………201
9.3.2.1 Dial Gages………………………………………………………………………….. 201
9.3.2.2 Commercially Available Gage Bolt ………………………………………… 202
9.3.2.3 Ultrasonic Measurements ……………………………………………………… 202
9.4 How Much Stretch? …………………………………………………………………………………….202
9.5 Problems Reduced by Stretch Control……………………………………………………………203
9.6 How to Get the Most Out of Stretch Control …………………………………………………204
9.7 Direct Preload Control—An Introduction………………………………………………………204
9.7.1 Strain-Gaged Bolts…………………………………………………………………………..205
9.7.2 Strain-Gaged Force Washers …………………………………………………………….205
9.7.3 Direct Tension Indicators …………………………………………………………………205
9.7.4 Squirter Self-Indicating DTIs…………………………………………………………….207
9.7.5 Twist-Off Tension-Control Bolts ……………………………………………………….207
9.7.6 Alternative-Design Fasteners …………………………………………………………….208
9.8 Bolt Tensioners …………………………………………………………………………………………..208
9.8.1 The Hardware …………………………………………………………………………………208
9.9 Bolt Heaters ……………………………………………………………………………………………….210
9.10 Problems Reduced by Direct Preload Control…………………………………………………210
9.10.1 Direct Tension Indicators …………………………………………………………………210
9.10.2 Twist-Off Bolts………………………………………………………………………………..211
9.10.3 Hydraulic Tensioners ……………………………………………………………………….211
9.10.4 Bolt Heaters ……………………………………………………………………………………211
9.11 Getting the Most Out of Direct Preload Control …………………………………………….211
9.11.1 Twist-Off Bolts and DTI Washers ……………………………………………………..211
9.11.2 Bolt Tensioners ……………………………………………………………………………….212
9.11.3 Bolt Heaters ……………………………………………………………………………………212
9.12 Ultrasonic Measurement of Stretch or Tension ……………………………………………….213
9.12.1 In General ………………………………………………………………………………………213
9.12.2 Principle of Operation………………………………………………………………………213
9.12.3 How It’s Used …………………………………………………………………………………214
9.12.4 Calibration of the Instrument ……………………………………………………………214
9.12.5 Presently Available Instruments…………………………………………………………215
9.13 Ultrasonic Measurements Using Plasma-Coated, Thin Film Transducers …………..215
Exercises and Problems …………………………………………………………………………………………215
References …………………………………………………………………………………………………………..216
Chapter 10
Theoretical Behavior of the Joint under Tensile Loads ……………………………………………..219
10.1 Basic Joint Diagram…………………………………………………………………………………….220
10.1.1 Elastic Curves for Bolt and Joint Members…………………………………………220
10.1.2 Determining Maximum and Minimum Residual Assembly Preload ……….220
10.1.2.1 The Equations………………………………………………………………….. 220
10.1.2.2 An Example …………………………………………………………………….. 222
10.1.3 Joint Diagram for Simple Tensile Loads …………………………………………….224
10.1.4 The Parable of the Red Rolls Royce…………………………………………………..226
10.1.5 Back to the Joint Diagram—Simple Tensile Load………………………………..227
10.2 Details and Variations …………………………………………………………………………………228
10.2.1 Changing the Bolt or Joint Stiffness …………………………………………………..228
10.2.2 Critical External Load ……………………………………………………………………..229
10.2.3 Very Large External Loads……………………………………………………………….230
10.2.4 Another Form of Joint Diagram ……………………………………………………….230
10.3 Mathematics of the Joint ……………………………………………………………………………..232
10.3.1 Basic Equations……………………………………………………………………………….232
10.3.2 Continuing the Example …………………………………………………………………..234
10.4 Loading Planes……………………………………………………………………………………………235
10.4.1 Tension Applied to Interface of Joint Members …………………………………..236
10.4.2 Mathematics of a Tension Load at the Interface………………………………….238
10.4.3 Significance of the Loading Planes …………………………………………………….238
10.4.4 Loading Planes within the Joint Members…………………………………………..239
10.4.5 Modifying Our Example to Include the Effects of Internal
Loading Planes………………………………………………………………………………..243
10.5 Dynamic Loads on Tension Joints…………………………………………………………………243
10.6 The Joint Under a Compressive Load ……………………………………………………………245
10.7 A Warning …………………………………………………………………………………………………245
Exercises and Problems …………………………………………………………………………………………246
References …………………………………………………………………………………………………………..247
Chapter 11
Behavior of the Joint Loaded in Tension: A Closer Look………………………………………….249
11.1 Effect of Prying Action on Bolt Loads …………………………………………………………..250
11.1.1 Definition of Prying …………………………………………………………………………250
11.1.2 Discussion of Prying ………………………………………………………………………..251
11.1.3 Prying Is Nonlinear………………………………………………………………………….255
11.2 Mathematics of Prying…………………………………………………………………………………256
11.2.1 In General ………………………………………………………………………………………256
11.2.2 VDI’s Analytical Procedure ………………………………………………………………256
11.2.3 Critical Loads and the Preloads Required to Prevent Joint Separation …..260
11.2.4 Bending Stress in the Bolt before Liftoff …………………………………………….261
11.2.5 Effects of Very Large External Loads…………………………………………………263
11.3 Other Nonlinear Factors………………………………………………………………………………263
11.3.1 Nut–Bolt System ……………………………………………………………………………..263
11.4 Thermal Effects …………………………………………………………………………………………..266
11.4.1 Change in Elasticity …………………………………………………………………………266
11.4.2 Loss of Strength………………………………………………………………………………267
11.4.3 Differential Thermal Expansion…………………………………………………………267
11.4.4 Stress Relaxation……………………………………………………………………………..271
11.4.5 Creep Rupture ………………………………………………………………………………..273
11.4.6 Compensating for Thermal Effects …………………………………………………….274
11.5 Joint Equations That Include the Effects of Eccentricity
and Differential Expansion …………………………………………………………………………..276
11.5.1 The Equations…………………………………………………………………………………276
11.5.2 An Example ……………………………………………………………………………………277
Exercises and Problems …………………………………………………………………………………………281
References …………………………………………………………………………………………………………..281
Chapter 12
In-Service Behavior of a Shear Joint……………………………………………………………………….283
12.1 Bolted Joints Loaded in Axial Shear ……………………………………………………………..283
12.1.1 In General ………………………………………………………………………………………283
12.1.2 Friction-Type Joints…………………………………………………………………………284
12.1.2.1 Bolt Load in Friction-Type Joints ………………………………………. 284
12.1.2.2 Stresses in Friction-Type Joints ………………………………………….. 285
12.1.3 Bearing-Type Joints …………………………………………………………………………285
12.1.3.1 Stresses in Bearing-Type Joints…………………………………………… 286
12.2 Factors That Affect Clamping Force in Shear Joints ……………………………………….286
12.3 Response of Shear Joints to External Loads …………………………………………………..288
12.4 Joints Loaded in Both Shear and Tension ………………………………………………………288
12.5 Present Definitions—Types of Shear Joint ……………………………………………………..290
Exercises ……………………………………………………………………………………………………………..290
References …………………………………………………………………………………………………………..291
Chapter 13
Introduction to Joint Failure …………………………………………………………………………………293
13.1 Mechanical Failure of Bolts ………………………………………………………………………..293
13.2 Missing Bolts…………………………………………………………………………………………….294
13.3 Loose Bolts……………………………………………………………………………………………….294
13.4 Bolts Too Tight …………………………………………………………………………………………295
13.5 Which Failure Modes Must We Worry About?……………………………………………..295
13.6 Concept of Essential Conditions ………………………………………………………………….295
13.7 Importance of Correct Preload ……………………………………………………………………297
13.7.1 Corrosion ……………………………………………………………………………………297
13.7.2 Stress Corrosion Cracking……………………………………………………………..297
13.7.3 Fatigue Failure …………………………………………………………………………….297
13.7.4 Mechanical Failure……………………………………………………………………….297
13.7.5 Self-Loosening of Fastener…………………………………………………………….297
13.7.6 Leakage ………………………………………………………………………………………297
13.8 Load Intensifiers ……………………………………………………………………………………….298
13.9 Failure of Joint Members……………………………………………………………………………298
13.10 Galling……………………………………………………………………………………………………..300
13.10.1 Discussion …………………………………………………………………………………..300
13.10.2 Removing Galled Studs…………………………………………………………………300
Exercises ……………………………………………………………………………………………………………..301
References …………………………………………………………………………………………………………..302
Chapter 14
Self-Loosening……………………………………………………………………………………………………..303
14.1 The Problem……………………………………………………………………………………………..303
14.2 How Does a Nut Self-Loosen?…………………………………………………………………….303
14.3 Loosening Sequence …………………………………………………………………………………..306
14.4 Junker’s Theory of Self-Loosening……………………………………………………………….306
14.4.1 The Equations ……………………………………………………………………………..307
14.4.2 The Long-Form Equation in Practice ……………………………………………..308
14.4.3 The Equation When Applied Torque Is Absent ……………………………….308
14.4.4 Why Slip Occurs? …………………………………………………………………………309
14.4.5 Other Reasons for Slip ………………………………………………………………….310
14.4.6 Other Theories of Self-Loosening……………………………………………………310
14.5 Testing for Vibration Resistance………………………………………………………………….310
14.5.1 NAS Test…………………………………………………………………………………….310
14.5.2 Junker Test………………………………………………………………………………….311
14.6 To Resist Vibration……………………………………………………………………………………312
14.6.1 Maintaining Preload and Friction…………………………………………………..313
14.6.1.1 Conventional Wisdom……………………………………………………. 313
14.6.2 Preventing Relative Slip between Surfaces ……………………………………….314
14.6.3 Countering Back-Off Torque …………………………………………………………315
14.6.3.1 Prevailing Torque Fasteners …………………………………………… 315
14.6.3.2 Nord-Lock Nuts and Washers………………………………………… 318
14.6.3.3 In General ……………………………………………………………………. 318
14.6.4 Double Nuts ………………………………………………………………………………..319
14.6.5 Mechanically Locked Fasteners ……………………………………………………..319
14.6.5.1 Lock Wires and Pins ……………………………………………………… 319
14.6.5.2 Welding ……………………………………………………………………….. 319
14.6.5.3 Stage 8 Fastening System ………………………………………………….. 319
14.6.5.4 Huck Lockbolt…………………………………………………………………. 320
14.6.5.5 Honeybee Robotics…………………………………………………………… 320
14.6.5.6 A-Lock Bolt and Nut ……………………………………………………….. 321
14.6.5.7 Omni-Lok Fasteners …………………………………………………………. 322
14.6.6 Chemically Bonded Fasteners ……………………………………………………………322
14.6.6.1 Rust ……………………………………………………………………………….. 322
14.6.6.2 Anaerobic Adhesives ………………………………………………………… 322
14.6.7 Vibration-Resistant Washers ……………………………………………………………. 323
14.6.7.1 Washers That Maintain Tension in the Fastener ………………….. 323
14.6.7.2 Toothed Washer ………………………………………………………………. 323
14.6.7.3 Helical Spring Washer ………………………………………………………. 324
14.6.7.4 Nord-Lock Washer…………………………………………………………… 324
14.6.8 Comparison of Options ……………………………………………………………………324
Exercises ……………………………………………………………………………………………………………..324
References and Bibliography………………………………………………………………………………….325
Chapter 15
Fatigue Failure …………………………………………………………………………………………………….327
15.1 Fatigue Process …………………………………………………………………………………………..327
15.1.1 Sequence of a Fatigue Failure……………………………………………………………327
15.1.1.1 Crack Initiation ……………………………………………………………….. 327
15.1.1.2 Crack Growth………………………………………………………………….. 328
15.1.1.3 Crack Propagation……………………………………………………………. 328
15.1.1.4 Final Rupture ………………………………………………………………….. 328
15.1.2 Types of Fatigue Failure…………………………………………………………………..328
15.1.3 Appearance of the Break ………………………………………………………………….329
15.2 What Determines Fatigue Life? …………………………………………………………………….329
15.2.1 S–N Diagrams…………………………………………………………………………………330
15.2.2 Material versus ‘‘The Part’’……………………………………………………………….332
15.2.3 Summary………………………………………………………………………………………..332
15.3 Other Types of Diagram ………………………………………………………………………………333
15.3.1 Constant Life Diagram …………………………………………………………………….333
15.3.2 Center Portion of Constant Life Diagram………………………………………….. 334
15.3.3 Approximate Constant Life Diagram …………………………………………………334
15.3.4 Endurance Limit Diagram ………………………………………………………………..336
15.3.5 Fatigue Life Data for Fasteners…………………………………………………………337
15.4 Influence of Preload and Joint Stiffness………………………………………………………….338
15.4.1 Fatigue in a Linear Joint…………………………………………………………………..338
15.4.2 Nonlinear Joints………………………………………………………………………………339
15.4.3 What Is the Optimum Preload? …………………………………………………………341
15.4.4 Fatigue and the VDI Joint Design Equations……………………………………… 341
15.5 Minimizing Fatigue Problems ……………………………………………………………………….343
15.5.1 Minimizing Stress Levels…………………………………………………………………..344
15.5.1.1 Increased Thread Root Radius…………………………………………… 344
15.5.1.2 Rolled Threads ………………………………………………………………… 344
15.5.1.3 Fillets ……………………………………………………………………………… 345
15.5.1.4 Perpendicularity ……………………………………………………………….. 345
15.5.1.5 Overlapping Stress Concentrations……………………………………… 345
15.5.1.6 Thread Run-Out ………………………………………………………………. 345
15.5.1.7 Thread Stress Distribution……………………………………………….. 345
15.5.1.8 Bending …………………………………………………………………………. 347
15.5.1.9 Corrosion ………………………………………………………………………. 347
15.5.1.10 Flanged Head and Nut ……………………………………………………. 347
15.5.1.11 Surface Condition …………………………………………………………… 348
15.5.2 Reducing Load Excursions ……………………………………………………………….348
15.5.2.1 Prevent Prying………………………………………………………………… 348
15.5.2.2 Proper Selection of Preload ……………………………………………… 348
15.5.2.3 Control of Bolt-to-Joint Stiffness Ratios ……………………………. 348
15.5.2.4 Achieving the Correct Preload………………………………………….. 348
15.6 Predicting Fatigue Life or Endurance Limit ……………………………………………………348
15.7 Fatigue of Shear Joint Members……………………………………………………………………349
15.8 Case Histories …………………………………………………………………………………………….351
15.8.1 Transmission Towers ……………………………………………………………………….351
15.8.2 Gas Compressor Distance Piece…………………………………………………………351
Exercises ……………………………………………………………………………………………………………..352
References and Bibliography………………………………………………………………………………….352
Chapter 16
Corrosion ……………………………………………………………………………………………………………355
16.1 Corrosion Mechanism………………………………………………………………………………….355
16.1.1 Galvanic Series………………………………………………………………………………..355
16.1.2 Corrosion Cell…………………………………………………………………………………356
16.1.3 Types of Cells………………………………………………………………………………….357
16.1.3.1 Two-Metal Corrosion ……………………………………………………… 357
16.1.3.2 Broken Oxide Film …………………………………………………………. 358
16.1.3.3 Stress Corrosion Cracking ……………………………………………….. 358
16.1.3.4 Crevice Corrosion …………………………………………………………… 359
16.1.3.5 Fretting Corrosion ………………………………………………………….. 359
16.2 Hydrogen Embrittlement ……………………………………………………………………………..360
16.2.1 Stress Cracking Failure Modes ………………………………………………………….360
16.2.2 Hydrogen Embrittlement Mechanism of Failure ………………………………….360
16.2.3 Susceptible and Safe Materials…………………………………………………………..361
16.2.4 Testing for Embrittlement…………………………………………………………………362
16.2.5 Fighting Hydrogen Embrittlement……………………………………………………..363
16.3 Stress Corrosion Cracking ……………………………………………………………………………363
16.3.1 Mechanism of Failure ………………………………………………………………………363
16.3.2 The Concept of KISCC ………………………………………………………………………364
16.3.3 Factors Affecting KISCC ……………………………………………………………………365
16.3.3.1 Bolt Material………………………………………………………………….. 365
16.3.3.2 The Environment ……………………………………………………………. 365
16.3.3.3 Thread-Forming Procedure ……………………………………………… 365
16.3.3.4 Bolt Strength or Hardness ……………………………………………….. 365
16.3.3.5 Type of Electrolyte………………………………………………………….. 367
16.3.3.6 Temperature…………………………………………………………………… 367
16.3.3.7 Bolt Diameter and Thread Pitch……………………………………….. 367
16.3.4 Combating SCC………………………………………………………………………………368
16.3.4.1 Susceptibility of the Material……………………………………………. 368
16.3.4.2 Eliminating the Electrolyte ………………………………………………. 369
16.3.4.3 Keeping Stress Levels below a Threshold Limit ………………….. 370
16.3.5 Surface Coatings or Treatment ………………………………………………………….374
16.3.6 Detecting Early SCC Cracks……………………………………………………………..376
16.4 Other Types of Stress Cracking …………………………………………………………………….376
16.4.1 Stress Embrittlement………………………………………………………………………..376
16.4.2 Hydrogen-Assisted Cracking ……………………………………………………………. 376
16.5 Minimizing Corrosion Problems……………………………………………………………………377
16.5.1 In General ………………………………………………………………………………………377
16.5.2 Detailed Techniques…………………………………………………………………………377
16.6 Fastener Coatings ……………………………………………………………………………………….379
16.6.1 In General ………………………………………………………………………………………379
16.6.2 Organic Coatings …………………………………………………………………………….380
16.6.2.1 Paints ……………………………………………………………………………. 380
16.6.2.2 Phos-Oil Coatings …………………………………………………………… 381
16.6.2.3 Solid-Film Organic Coatings ……………………………………………. 381
16.6.3 Inorganic or Metallic Coatings ………………………………………………………….381
16.6.3.1 Electroplated Coatings…………………………………………………….. 382
16.6.3.2 Hot-Dip Coatings …………………………………………………………… 382
16.6.3.3 Mechanical Plating …………………………………………………………. 382
16.6.3.4 Miscellaneous Coating Processes ………………………………………. 383
16.6.4 Composite Coatings …………………………………………………………………………383
16.6.5 Rating Corrosion Resistance ……………………………………………………………. 387
16.6.6 Substitutes for Cadmium Plate ………………………………………………………….387
Exercises ……………………………………………………………………………………………………………..388
References and Bibliography………………………………………………………………………………….388
Chapter 17
Selecting Preload for an Existing Joint ……………………………………………………………………391
17.1 How Much Clamping Force Do We Want? …………………………………………………… 391
17.1.1 Factors to Consider …………………………………………………………………………391
17.1.1.1 Joint Slip ……………………………………………………………………….. 392
17.1.1.2 Self-Loosening ……………………………………………………………….. 392
17.1.1.3 Pressure Loads……………………………………………………………….. 392
17.1.1.4 Joint Separation……………………………………………………………… 393
17.1.1.5 Fatigue ………………………………………………………………………….. 393
17.1.2 Placing an Upper Limit on the Clamping Force…………………………………..393
17.1.2.1 Yield Strength of the Bolt………………………………………………… 394
17.1.2.2 Thread-Stripping Strength ……………………………………………….. 394
17.1.2.3 Design-Allowable Bolt Stress and Assembly Stress Limits……. 394
17.1.2.4 Torsional Stress Factor……………………………………………………. 394
17.1.2.5 Shear Stress Allowance ……………………………………………………. 395
17.1.2.6 Stress Cracking ………………………………………………………………. 395
17.1.2.7 Combined Loads…………………………………………………………….. 395
17.1.2.8 Damage to Joint Members ………………………………………………. 395
17.1.2.9 Distortion of Joint Members ……………………………………………. 395
17.1.2.10 Gasket Crush …………………………………………………………………. 396
17.1.3 Summarizing Clamping Force Limits …………………………………………………396
17.2 Simple Ways to Select Assembly Preloads ………………………………………………………397
17.2.1 Best Guide: Past Experience ……………………………………………………………..397
17.2.2 Second Best: Ask the Designer ………………………………………………………….398
17.2.3 Unimportant Joint: No Prior Experience ……………………………………………398
17.2.4 When More Care Is Indicated …………………………………………………………..398
17.2.5 If Improvements Are Required ………………………………………………………….400
17.2.6 Selecting Preload for Critical Joints……………………………………………………400
17.3 Estimating the In-Service Clamping Force ……………………………………………………..400
17.3.1 Basic Assumptions …………………………………………………………………………..402
17.3.2 Combining the Scatter Effects …………………………………………………………..402
17.4 Relating Desired to Anticipated Bolt Tensions………………………………………………..408
17.5 Which Variables to Include in the Analysis …………………………………………………….410
17.5.1 In General ………………………………………………………………………………………410
17.5.2 Possible Factors to Include ……………………………………………………………….411
17.5.3 Which Should We Include?……………………………………………………………….411
17.6 ASTM F16.96 Subcommittee on Bolting Technology ………………………………………412
17.7 A More Rigorous Procedure…………………………………………………………………………412
17.7.1 Experiments Required for True Accuracy …………………………………………..413
17.7.2 The Equations…………………………………………………………………………………413
17.7.3 Minimum Clamping Force—Some Examples………………………………………414
17.7.3.1 First Example—Using Worst-Case Values …………………………… 414
17.7.3.2 Second Example—Using Statistically Combined Values………… 415
17.7.3.3 Third Example—Using Average Values ………………………………. 416
17.7.3.4 Fourth Example—Using Feedback Control Values ………………. 417
17.7.4 Maximum Bolt Tension ……………………………………………………………………417
17.8 NASA’s Space Shuttle Preload Selection Procedure…………………………………………418
17.8.1 Calculating Maximum and Minimum Preloads……………………………………418
17.8.2 Confirming the Preload Calculations………………………………………………….420
17.8.3 Discussion ………………………………………………………………………………………420
Exercises ……………………………………………………………………………………………………………..421
References and Bibliography………………………………………………………………………………….421
Chapter 18
Design of Joints Loaded in Tension………………………………………………………………………..423
18.1 A Major Goal: Reliable Joints………………………………………………………………………423
18.1.1 Checklist for Reliable Bolted Joints……………………………………………………423
18.2 Typical Design Steps ……………………………………………………………………………………424
18.2.1 Initial Definitions and Specifications ………………………………………………….425
18.2.2 Preliminary Design…………………………………………………………………………..425
18.2.3 Load Estimates ……………………………………………………………………………….425
18.2.4 Review Preliminary Layouts: Define the Bolts …………………………………….426
18.2.5 Clamping Force Required…………………………………………………………………426
18.2.5.1 Minimum Clamp ……………………………………………………………… 426
18.2.5.2 Maximum Clamp……………………………………………………………… 427
18.3 Joint Design in the Real World …………………………………………………………………….427
18.4 VDI Joint Design Procedure …………………………………………………………………………427
18.4.1 Terms and Units ……………………………………………………………………………..428
18.4.2 Design Goals…………………………………………………………………………………..429
18.4.3 General Procedure …………………………………………………………………………..429
18.4.4 Estimating Assembly Preloads: Preliminary Estimate of Minimum
and Maximum Assembly Preloads……………………………………………………..430
18.4.5 Adding the Effects of the External Load …………………………………………….431
18.4.6 Is the Required Force Good Enough? ………………………………………………..432
18.4.7 Further Considerations …………………………………………………………………….433
18.4.7.1 Static Strength of the Bolt ……………………………………………….. 433
18.4.7.2 Fatigue ………………………………………………………………………….. 433
18.4.7.3 Bearing Stress…………………………………………………………………. 434
18.4.7.4 Shear Stress……………………………………………………………………. 434
18.4.7.5 Bending Stress………………………………………………………………… 434
18.4.7.6 Eccentric Loading …………………………………………………………… 434
18.4.8 Revised Bolt Specifications ……………………………………………………………..435
18.5 An Example ……………………………………………………………………………………………….435
18.5.1 Inputs …………………………………………………………………………………………..435
18.5.2 Calculations…………………………………………………………………………………..436
18.5.2.1 Maximum and Minimum Assembly Preloads……………………… 436
18.5.2.2 Static Strength of the Bolts ………………………………………………. 436
18.5.2.3 Fatigue Strength …………………………………………………………….. 437
18.5.2.4 Contact Stress ………………………………………………………………… 437
18.6 Other Factors to Consider When Designing a Joint …………………………………………437
18.6.1 Thread Strength …………………………………………………………………………….437
18.6.2 Flexible Bolts ………………………………………………………………………………..438
18.6.3 Accessibility…………………………………………………………………………………..438
18.6.4 Shear versus Tensile Loads ……………………………………………………………..438
18.6.5 Load Magnifiers…………………………………………………………………………….438
18.6.6 Minimizing Embedment………………………………………………………………….438
18.6.7 Differential Expansion ……………………………………………………………………438
18.6.8 Other Stresses in Joint Members………………………………………………………438
18.6.9 Locking Devices …………………………………………………………………………….439
18.6.10 Hole Interference……………………………………………………………………………439
18.6.11 Safety Factors ……………………………………………………………………………….439
18.6.12 Selecting a Torque to be Used at Assembly……………………………………….439
Exercises ……………………………………………………………………………………………………………..440
References …………………………………………………………………………………………………………..440
Bibliography………………………………………………………………………………………………………..440
Chapter 19
Design of Joints Loaded in Shear …………………………………………………………………………..443
19.1 An Overview ………………………………………………………………………………………………443
19.2 The VDI Procedure Applied to Shear Joints …………………………………………………..444
19.3 How Shear Joints Resist Shear Loads ……………………………………………………………446
19.3.1 In General …………………………………………………………………………………….446
19.3.2 Concept of Slip-Critical Joints …………………………………………………………446
19.4 Strength of Friction-Type Joints ……………………………………………………………………448
19.4.1 In General …………………………………………………………………………………….448
19.4.2 Allowable Stress Procedure……………………………………………………………..449
19.4.3 Other Factors to Consider ………………………………………………………………449
19.4.4 Slip Coefficients in Structural Steel…………………………………………………..450
19.4.5 An Example ………………………………………………………………………………….451
19.4.5.1 Minimum Preload Required to Prevent Slip……………………….. 453
19.4.5.2 Alternate Using the Allowable Stress Procedure …………………. 454
19.5 Strength of Bearing-Type Joints ……………………………………………………………………455
19.5.1 Shear Strength of Bolts …………………………………………………………………..455
19.5.1.1 Distribution of Load among the Bolts……………………………….. 455
19.5.1.2 Shear Strength Calculations……………………………………………… 456
19.5.2 Tensile Strength of Joint Plates………………………………………………………….457
19.5.3 Bearing Stress………………………………………………………………………………….457
19.5.4 Tearout Strength ……………………………………………………………………………..458
19.5.5 Summary………………………………………………………………………………………..459
19.5.6 Clamping Force Required by a Bearing-Type Joint ……………………………..459
19.6 Eccentrically Loaded Shear Joints …………………………………………………………………459
19.6.1 Rotation about an Instant Center………………………………………………………459
19.6.2 Rotation about the Centroid of the Bolt Group…………………………………..461
19.6.2.1 Find the Centroid of the Bolt Group ………………………………….. 461
19.6.2.2 Estimating the Shear Stress on the Most Remote Bolt…………… 462
19.7 Allowable Stress versus Load and Resistance Factor Design …………………………….465
Exercises ……………………………………………………………………………………………………………..466
References …………………………………………………………………………………………………………..466
Appendix A
Units and Symbol Log ………………………………………………………………………………………….467
Appendix B
Glossary of Fastener and Bolted Joint Terms…………………………………………………………..475
Appendix C
Sources of Bolting Information and Standards…………………………………………………………483
Appendix D
English and Metric Conversion Factors…………………………………………………………………..485
Appendix E
Tensile Stress Areas for English and Metric Threads with Estimated ‘‘Typical’’
Preloads and Torques for As-Received Steel Fasteners ……………………………………………..487
Appendix F
Basic Head, Thread, and Nut Lengths…………………………………………………………………….497
Index…………………………………………………………………………………………………………………..505

Preface to the Fourth Edition

This fourth edition stands on the shoulders of the first three editions, so I have included
large excerpts from their prefaces once again. These detail the steps taken—and the themes
developed—to reach this point. The acknowledgments found in the third edition are still valid
too, so they are also included. At the end of this preface I express my thanks for the additional
help provided for this present text.
The third edition was just under 1,000 pages in length, so it was clearly undesirable to
create a longer, single volume, fourth edition. Experience in conducting bolting seminars, and
through contacts with readers has shown, furthermore, that the audience for this text comes
in two flavors. Many users deal primarily with gasketed, pressure vessel, and piping joints.
The rest deal with the types of non-gasketed joints found in the auto, aerospace, structural
steel, heavy equipment, mass production, and other industries. So it was decided that this
fourth edition should be published in two volumes, one for each group. It was further decided
that Volume 2, for gasketed joint users, should be coauthored by me and by Jim Payne. Jim is
an internationally recognized expert in PVP joints, and is very active in ASME, the Pressure
Vessel Research Council, and other groups that sponsor research and write standards dealing
with gasketed joints. Jim will write all of the chapters whose focus is the gasketed joint. I will
contribute those chapters pertinent to any bolted joint: on the basic behavior of joints and
bolts, on materials, on threads, on torque and other preload control means, on failure modes
common to gasketed and non-gasketed joints, etc. This generic material will also, of course,
be included in the volume designed for those dealing with non-gasketed joints, so there will be
a great deal of redundancy between the two volumes. We expect that only a few readers will
need or want both volumes.
Previous editions have been used by practicing engineers, and have rarely if ever been used
as a classroom text. An attempt has been made this time to make it more attractive not only to
people in the field but also to teachers. A set of problems or exercises has been included at the
end of each chapter. Answers to these will be found in the Appendix. All of the information
required to answer the questions or do the exercises can be found in the book, either in the
text or in the tables of data found in the Appendices. In fact, many of the exercises have been
designed to force the student to search for information or data not in the chapter containing
those exercises but elsewhere in the book, to encourage him to learn how to use the book
more effectively. These exercises should also help to fix the material in the mind of a homebased
student. An attempt has also been made to create a leaner, meaner text: long winded
historical discussions, redundancies, irrelevancies and the like have been excluded this time so
that basic ideas, data, and themes will be easier to find and use. The overall goal is a useful
text that can also be used for training purposes.
Much material has been eliminated, but a lot of new information has been added. This is
scattered throughout both volumes and generally involves an update of material already
included in the previous edition. These updates are based on the latest revisions to various
bolting standards, on information obtained from colleagues who are active in the field, and
from that wonderfully helpful source of information that was not available to me when I
created previous editions—the Web. The latter is so useful that, in several places including the
Appendices, I’ve given the addresses of many Web sites you will find especially useful when
working with or studying bolted joints.
There are no new chapters in this Volume 1. Changes and additions have sometimes only
required a sentence or two, more frequently a new paragraph, and occasionally a couple of
pages. New information includes such things as revised designations for several bolting
materials; new products and procedures to fight self-loosening; new ways to control preload,
including the SquirterTM, a tension-indicating washer; new ultrasonic equipment for measuring
bolt stretch or preload, including a plasma-coated, thin-film, ultrasonic transducer; a
NASA procedure for selecting preload for space shuttle bolts, revised specifications and
definitions for the design of joints loaded in shear; and current practices and tools for mass
production bolting.