THIRD EDITION Practical Non-Destructive Testing Baldev Raj T. Jayakumar M. Thavasimuthu CD Alpha Science International Ltd. Oxford, U. K.
---------------Contents Foreword Preface to the Third Edition Preface to the First Edition CHAPTER 1. Non-Destructive Testing: An Introduction CHAPTER 2. Visual Inspection 2.1 Basic Principle 4 2.2 The Eye 4 2.2.1 Defects which can be detected by unaided visual inspection 5 2.3 Optical Aids Used for Visual Inspection 5 2.3.1 Microscope 5 2.3.2 Borescope 6 2.3.3 Endoscope 6 2.3.4 Flexible fibre-optic Borescope (Flexiscope) 6 2.3.5 Telescope 7 2.3.6 Holography 7 2.4 Applications 7 CHAPTER 3. Liquid Penetrant Testing 3.1 Physical Principles 8 3.2 Procedure for Penetrant Testing 9 3.2.1 Cleaning 9 3.2.2 Penetrant application 10 3.2.3 Removal of excess penetrant 10 3.2.4 Application of developer 10 3.2.5 Inspection and evaluation 10 3.3 Penetrant Testing Materials JJ 3.3.1 Penetrants 11 3.3.2 Cleaners and emujsitiers 11 3.3.3 Developers 11 3.3.4 Special requirements 12 3.3.5 Test blocks 12 v vii i.x 1 4 8
xii Contents _ 3.4 Penetrant Testing Methods 12 3.4.1 Water washable method /2 3.4.2 Post-emulsifiable method /3 3.4.3 Solvent removable method /4 3.5 Sensitivity 14 3.6 Applications and Limitations 15 3.7 Standards 16 3.8 Typical Examples 16 CHAPTER 4. Magnetic Particle Testing 4.1 Magnetism-Basic Definitions and Principle of MPT 21 4.1.1 Principle of MPT 22 4.2 Magnetizing Techniques 22 4.2.1 Magnetization using a magnet 23 4.2.2 Magnetization using an electromagnet 23 4.2.3 Contact current flow method 23 4.2.4 Using the threading bar 24 4.2.5 The coil 24 4.2.6 Induced current flow 25 4.3 Procedure Used for Testing a Cümponent 26 4.4 Equipment Used for MPT 28 4.5 Sensitivity 29 4.6 Limitations 30 4.7 Standards 30 4.8 Typical Examples 30 CHAPTER 5. Eddy Current Testing 5.1 Principles 33 5.2 Instrumentation für ECT 36 5.3 Techniques 40 5.3.1 High sensitivity techniques 40 5.3.2 Inspection of heal exchanger tubes by single frequency ECT system 41 5.3.3 Multifrequency ECT 43 5.3.4 High frequency ECT 46 5.3.5 3D or phased array ECT 46 5.3.6 InspectiQn offerromagnetic materials 47 5.4 Sensitivity 49 5.5 Advanced Eddy Current Test Methods 49 5.5.1 Magneto-optic/eddy current imaging (MOl) 49 5.5.2 Pulsed eddy current testing 51 5.5.3 Low frequency eddy current lesting 58 5.5.4 SQUID based eddy current testing 61 5.6 Applications 61 5.7 Limitations 62 5.8 Standards 62 CHAPTER 6. Radiography 6.1 Basic Principle 63 21 33 63
------------------------ Contents xiii 6.2 Eleetromagnetie Radiation Sourees 64 6.2.1 X-ray souree 64 6.2.2 Produetion of X-rays 65 6.2.3 High energy X-ray souree 66 6.2.4 Gamma ray sources 66 6.2.5 Properties of X- and gamma rays 67 6.3 Radiation Attenuation in the Speeimen 67 6.4 Effeet of Radiation on Film 67 6.4. L Film ionisation 67 6.4.2 Inherent unsharpness 67 6.5 Radiographie Imaging 68 6.5.1 GeometrieaJ faetors 68 6.5.2 Radiographie film 68 6.5.3 Intensifying sereens 69 6.5.4 Film density 70 6.5.5 Radiographie sensitivity 70 6.5.6 Penetrameter 71 6.5.7 Determining radiographie exposure 72 6.6 lnspeetion Teehniques 72 6.6.1 Single wall single image teehnique 72 6.6.2 Double wall penetration teehnique 72 6.6.3 Latitude teehnique 73 6.6.4 Special teehniques 75 6.7 Applieations of Radiographie Inspeetion 76 6.8 Limitations 76 6.9 Typical Examples 77. 6.10 Real Time Radiography 80 6.11 Mierofoeal Radiography 83 6.11.1 Advantages and limitations of mierofoeal radiography, 83 6.11.2 Applieations 84 6.12 Safety in Industrial Radiography 85 6.12.1 Radiation units 85 6.12.2 Limits for radiation exposure 86 6.12.3 Methods for exposure eontrol 86 6.12.4 Radiation monitoring 86 6.13 Standards 86 6.14 Neutron Radiography 87 6.14.1 Prineiples of neutron radiography 87 6.14.2 Neutron sources 88 6.14.3 Moderator and eollimator 89 6.14.4 Neutron deteetion 89 6.14.5 Applieations ofneutron radiography 91 CHAPTER 7. Ultrasonic Testing 7.1 Basie Properties of Sound Beam 93 7.1.1 Sound waves 93 7.1.2 Veloeity"ofultrasoniewaves 95 7.1.3 Aeoustie impedanee 96 7.1.4 Behaviour of ultrasonic waves 96 93
xiv Contents' _ 7.2 Ultrasonic Transducers 97 7.2.1 Characteristics of ultrasonic beam 98 7.2.2 Attenualion 99 7.3 Inspection Methods 100 7.3.1 Normal incident pulse-echo inspection 100 7.3.2 Normal incident through-transmission testing 101 7.3.3 Angle beam pulse-echo testing 101 7.3.4 Criteria for probe selection 101 7.3.5 Flaw sensitivity 101 7.3.6 Beam divergence 102 7.3.7 Penetration and resolution 102 7.4 Techniques for Nonnal Beam Inspection 102 7.4.1 Fatigue cracks 102 7.4.2 IncJusions, slag, porosity, and large grain structure 103 7.4.3 Thickness measurement: corrosion deteclion 103 7.4.4 Intergranular cracks: hydrogen attack 104 7.5 Techniques for Angle Beam Inspection 104 7.5.1 Pipe inspeclion 106 7.6 Flaw Characterisation Techniques 106 7.7 Ultrasonic Flaw Detection Equipment 107 7.8 Modes of Display 109 7.8.1 A-scan 109 7.8.2 B-scan 109 7.8.3 C-scan 109 7.9 Immersion Testing 110 7.10 Applications of Ultrasonic Testing 110 7.11 Advantages 110 7.12 Limitations 110 7.13 Standards 111 7.14 Mechanical Impedance Analysis Technique 111 7.14.1 Introduction and basic principle I I I 7.14.2 Measurement of variations in mechanical impedance I 12 7.14.3 Applications and limitations JJ5 CHAPTER 8. Acoustic Emission Testing 8.1 Principle of AET 116 8.2 Technique 117 8.3 Instrumentation 118 8.4 Sensitivity 120 8.5 Applications 120 8.6 Standards 120 8.7 Structural Integrity Assessment 121 8.7.1 Hydro testing of a Horten sphere /21 8.8 Acoustic Emission Technique for Leak Defection 122 8.8.1 Leak defection in an end shield of a PHWR /23 CHAPTER 9. Thermography 9.1 Basic Principles 125 116 125
Contents xv 9.2 Oetectors and Equipment 126 9.3 Techniques 127 9.4 Applications 127 9.4.1 Thermal imagining for eondition monitoring of industrial eomponent 129 9.5 Codes and Standards 131 CHAPTER 10. In situ Metallographie Examination 132 10.1 Approach to the Selection of Site for Metallographie Examination 133 10.2 Replication Process 133 10.3 Significance of Microstructural Observation 134 10.4 Oecision Making 135 10.5 Applications 13) 10.6 Codes and Standards 135 10.7 Typieal Case-Studies for assessment of components by IN-SITU Metallography 136 10.7.1 Assessment of degration of a heavy water plant eomponent 136 CHAPTER 11. Leak Testing 11.1 Measurement of Leakage 139 11.2 Leak Testing Methods 140 11.3 Leak Oetection 140 11.3.1 Bubble testing 141 11.3.2 Helium leak deteetor 141 11.4 Standards 143 CHAPTER 12. Comparison and Seleetion of NDT Methods 12.1 Oefects in Materials 145 12.1.1 Metallurgieal proeess and defeets 146 Casting defects 146 Forging and roljing defects 148 Extrusion defects 149 Drawing defects 150 Welding defects 150 Grinding cracks 153 Heat treating cracks 154 12.1.2 Defeets introdueed during service 154 Cause of material failures Types of material failures 154 155 12.2 Selection of the NOT Method 157 12.2.1 Visual testing (VT) 157 12.2.2 Liquid penetrant testing 158 12.2.3 Magnetic particle testing 158 12.2.4 Eddy eurrent testing 159 12.2.5 Radiographie testing (RT) 159 12.2.6 Ultrasonic testing (UT) 160 12.2.7 Aeoustie emission testing (AET) 161 12.2.8 Thermography 162 12.2.9 Summary 162 12.3 Selection of Instrumentation 162 12.3.1 Visual testing 139 139 145
xvi Contents 12.3.2 Liquid penetrant testing 163 12.3.3 Magnetic particle testing 164 12.3.4 Eddy current testing 164 12.3.5 Radiography testing 165 12.3.6 Ultrasonic testing 166 12.3.7 Acoustic emission testing 167 12.3.8 Thermography 168 12.4 Summary 169 CHAPTER 13. ProbabiJity of Detection Concepts in NDT 172 13.1 Introduction 172 13.2 ProbabiIity of Detection (POD): The Approach 173 13.3 TypicaI Methodology for Establishing POD 174 13.4 Role of POD Concepts During Design and Operation 176 CHAPTER 14. Statistical Methods for Quality Control 179 14.1 Probability 180 14.1.1 Basic concepts 180 14.1.2 Prabability sampie space and tlaw si~e distribution 181 14.1.3 Effect of inspection on f1aw size distribution 182 14.2 Statistical Methods 183 14.2.1 Basic principles 183 14.2.2 Contra1 charts 185 14.2.3 Basic princip1es of acceptance samp1ing inspection 188 14.2.4 Sampling plans 190 14.3 Taguchi Concepts in Quality Control 191 14.3.1 Basic concepts 191 14.4 Total Quality Management 192 14.4.1 Quality 192 14.4.2 Deming's philosophy 193 14.4.3 Concept of total quality management 193 14.4.4 Key ingredients of total quality management 195 14.5 Summary 195 CHAPTER 15. Codes, Standards, Specification and Procedures 196 15.1 Code 197 15.2 Standards 197 15.2.1 International and national standards 198 15.2.2 Industry standards 198 15.2.3 Government and military standards 198 15.2.4 Industry practices 198 15.2.5 Company standards 198 15.3 Specification 199 15.4 Procedures 199 15.5 Indian National Standards for NDT 200 15.6 International Standards far NDT 200 15.6.1 ISO standards for quality systems 200 15.7 Conclusion 202 GENERAL REFERENCES 203 INDEX 206