TO 33B-1-1NAVAIR 01-1A-16-1

TM 1-1500-335-23TECHNICAL MANUAL

NONDESTRUCTIVE INSPECTION METHODS, BASIC THEORY

(ATOS)

THIS MANUAL SUPERSEDES TO 33B-1-1/NAVAIR 01-1A-16-1/TM 1-1500-335-23, DATED 15 MAY 2014.

ARMY Wherever the text of this manual refers to Air Force technical orders for supportive information,PERSONNEL: refer to the comparable Army documents.

NAVY OPNAV instruction 4790.2 and weapon system specific manuals take precedence over this manual.PERSONNEL:

DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. PA Case Number 72ABW-2013-0007. Submitrecommended changes or problems with this Technical Order to AFLCMC/LZPTP.

Published under Authority of the Secretary of the Air Force

15 OCTOBER 2016

TO 33B-1-1NAVAIR 01-1A-16-1TM 1-1500-335-23

INSERT LATEST CHANGED PAGES. DESTROY SUPERSEDED PAGES.

LIST OF EFFECTIVE PAGESNOTE: The portion of the text affected by the changes is indicated by a vertical line in the outer

margins of the page. Changes to illustrations are indicated by shaded or screened areas,or by miniature pointing hands.

Dates of issue for original and changed pages are:

Original . . . . . . . . . . . . . . . . . . . . 0 . . . . . . . . . . 15 October 2016

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A USAF

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TABLE OF CONTENTS

Chapter Page

INTRODUCTION............................................................................................................................................................ xxi

SAFETY SUMMARY...................................................................................................................................................xxiii

1 NONDESTRUCTIVE INSPECTION METHODS, GENERAL INFORMATION ......................................................1-1

SECTION I NONDESTRUCTIVE INSPECTION (NDI) METHODS ......................................................................1-1

1.1 Why We Do Nondestructive Inspection (NDI)................................................................................................1-11.1.1 Nondestructive Inspection Data ........................................................................................................................1-11.1.2 Structural Management Programs.....................................................................................................................1-11.1.3 Mechanisms for Using NDI Data .....................................................................................................................1-11.1.4 Tools for Gathering NDI Data..........................................................................................................................1-2

SECTION II PERSONNEL TRAINING/QUALIFICATION/CERTIFICATION ......................................................1-3

1.2 Personnel Training/Qualification/Certification .................................................................................................1-31.2.1 Training Introduction.........................................................................................................................................1-31.2.2 Training Requirements ......................................................................................................................................1-31.2.3 Certification Requirements................................................................................................................................1-31.2.4 Experience Hours Documentation ....................................................................................................................1-41.2.5 Physical Requirements ......................................................................................................................................1-41.2.6 Requirement for Special Task Certification and Recurring Training..............................................................1-5

SECTION III REPORTING NEW OR IMPROVED NDI TECHNIQUES ...............................................................1-7

1.3 Reporting New/Improved Nondestructive Inspection Techniques ..................................................................1-71.3.1 Need for Reporting New and Improved Techniques .......................................................................................1-71.3.2 Authority ............................................................................................................................................................1-71.3.3 AFTO Form 242................................................................................................................................................1-71.3.4 Scope..................................................................................................................................................................1-71.3.5 Responsibilities for Updating Techniques ........................................................................................................1-71.3.6 AFTO Form 242 Entries ...................................................................................................................................1-8

SECTION IV NDI EQUIPMENT ..............................................................................................................................1-11

1.4 Procuring NDI Equipment (AIR FORCE Only) ............................................................................................1-111.4.1 Centrally Procured NDI Equipment................................................................................................................1-111.4.2 Weapon System Specific/Special Purpose Equipment...................................................................................1-111.4.3 Local Purchase Equipment..............................................................................................................................1-11

SECTION V PROCESS CONTROL..........................................................................................................................1-12

1.5 Process Control................................................................................................................................................1-121.5.1 Reason for Controlling the Process ................................................................................................................1-121.5.2 Scope of Process Control ................................................................................................................................1-121.5.3 Process Control Documentation Requirements ..............................................................................................1-121.5.4 Establishing a Documentation Method...........................................................................................................1-121.5.5 Suggested Documentation Method .................................................................................................................1-12

SECTION VI LABORATORY INFORMATION .....................................................................................................1-13

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1.6 General Laboratory Information .....................................................................................................................1-131.6.1 Constructing a Nondestructive Inspection Laboratory...................................................................................1-131.6.2 Building Requirements ....................................................................................................................................1-141.6.3 Electrical and Mechanical Requirements........................................................................................................1-151.6.4 Room Identification.........................................................................................................................................1-15

2 LIQUID PENETRANT INSPECTION METHOD ........................................................................................................2-1

SECTION I LIQUID PENETRANT (LT) INSPECTION METHOD ........................................................................2-1

2.1 General Capabilities of Liquid Penetrant Inspection .......................................................................................2-12.1.1 Introduction to Liquid Penetrant Inspection.....................................................................................................2-12.1.2 Background of Liquid Penetrant Inspection.....................................................................................................2-12.1.3 Why Use Liquid Penetrant Inspection..............................................................................................................2-12.1.4 Limitations of Liquid Penetrant Inspection ......................................................................................................2-12.1.5 Advantages of Liquid Penetrant Inspection......................................................................................................2-32.1.6 Disadvantages of Liquid Penetrant Inspection .................................................................................................2-32.1.7 Basic Penetrant Inspection Process...................................................................................................................2-42.1.8 Personnel Requirements ....................................................................................................................................2-52.1.9 Understanding Penetrant Classification and Processes ....................................................................................2-52.1.10 Qualification of Penetrant Material ..................................................................................................................2-92.1.11 Qualification of Penetrant Sensitivity.............................................................................................................2-102.1.12 Penetrant Material Performance......................................................................................................................2-10

SECTION II PRINCIPLES AND THEORY OF LIQUID PENETRANT INSPECTION.......................................2-11

2.2 Principles and Theory of Liquid Penetrant Inspection ..................................................................................2-112.2.1 General.............................................................................................................................................................2-112.2.2 Characteristics of a Penetrant..........................................................................................................................2-112.2.3 Mechanisms of Penetrant Action ....................................................................................................................2-112.2.4 How Liquid Penetrant Enters Discontinuities ................................................................................................2-172.2.5 Mechanisms and Principles of Penetrant Removal ........................................................................................2-172.2.6 Mechanisms of Developer Action ..................................................................................................................2-212.2.7 Cleaning and Surface Preparation...................................................................................................................2-222.2.8 Surface Conditions Affecting Penetrant Inspection .......................................................................................2-222.2.9 Contaminants and Soils...................................................................................................................................2-222.2.10 Coatings ...........................................................................................................................................................2-282.2.11 Effects of Surface Deformation, Wear, and Surface Roughness on Penetrant Inspection ...........................2-30

SECTION III LIQUID PENETRANT INSPECTION EQUIPMENT.......................................................................2-32

2.3 Equipment ........................................................................................................................................................2-322.3.1 General.............................................................................................................................................................2-322.3.2 Portable Equipment .........................................................................................................................................2-322.3.3 Stationary Inspection Equipment - General Purpose .....................................................................................2-322.3.4 Small Parts Inspection Systems ......................................................................................................................2-322.3.5 Automated Inspection Systems .......................................................................................................................2-322.3.6 Inspection Lamps.............................................................................................................................................2-322.3.7 Process Control Equipment.............................................................................................................................2-39

SECTION IV LIQUID PENETRANT APPLICATION METHODS .......................................................................2-41

2.4 Application Method.........................................................................................................................................2-412.4.1 General.............................................................................................................................................................2-412.4.2 Basic Penetrant Processes ...............................................................................................................................2-412.4.3 Pre-Testing.......................................................................................................................................................2-462.4.4 Pre-Cleaning Performed by NDI Personnel ...................................................................................................2-462.4.5 Penetrant Application ......................................................................................................................................2-472.4.6 Temperature Limitations .................................................................................................................................2-50

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2.4.7 Penetrant Dwell ...............................................................................................................................................2-522.4.8 Penetrant Removal...........................................................................................................................................2-582.4.9 Water Washing/Rinsing Technique ................................................................................................................2-712.4.10 Drying ..............................................................................................................................................................2-722.4.11 Application of Developers ..............................................................................................................................2-742.4.12 Post-Cleaning After Penetrant Inspection.......................................................................................................2-852.4.13 Protection of Parts Following Penetrant Inspection.......................................................................................2-86

SECTION V INTERPRETATION OF LIQUID PENETRANT INSPECTION ......................................................2-87

2.5 Interpretation of Indications ............................................................................................................................2-872.5.1 General.............................................................................................................................................................2-872.5.2 Importance of Understanding the Interpretation Process ...............................................................................2-872.5.3 Personnel Requirements ..................................................................................................................................2-872.5.4 Lighting............................................................................................................................................................2-872.5.5 Inspection Conditions ......................................................................................................................................2-932.5.6 Evaluating Indications .....................................................................................................................................2-93

SECTION VI PROCESS CONTROL OF LIQUID PENETRANT INSPECTION................................................2-101

2.6 Liquid Penetrant Process Control .................................................................................................................2-1012.6.1 General...........................................................................................................................................................2-1012.6.2 Need for Process Quality ..............................................................................................................................2-1012.6.3 Why Test New Materials ..............................................................................................................................2-1012.6.4 Why Test In-Use Materials ...........................................................................................................................2-1012.6.5 Causes of Material Degradation....................................................................................................................2-1012.6.6 Establishing Work Center Process Control Intervals ...................................................................................2-1022.6.7 Process Control Equipment...........................................................................................................................2-1022.6.8 Process Checks ..............................................................................................................................................2-1052.6.9 Control of New Materials .............................................................................................................................2-1112.6.10 Testing In-Use Materials ...............................................................................................................................2-113

SECTION VII SPECIAL PURPOSE LIQUID PENETRANTS .............................................................................2-123

2.7 Special Purpose Liquid Penetrant .................................................................................................................2-1232.7.1 General...........................................................................................................................................................2-1232.7.2 Liquid Oxygen (LOX) Compatible Penetrants.............................................................................................2-1232.7.3 Low Sulfur, Low Chlorine Penetrant Systems.............................................................................................2-1242.7.4 High Temperature Penetrant Materials .........................................................................................................2-1242.7.5 Dye Precipitation Penetrant Systems ............................................................................................................2-1242.7.6 Reversed Fluorescence Method ....................................................................................................................2-1242.7.7 Thixotropic Penetrant ....................................................................................................................................2-1252.7.8 Dilution Expansion Developers ....................................................................................................................2-1252.7.9 Plastic-Film Developers ................................................................................................................................2-125

SECTION VIII LIQUID PENETRANT INSPECTION SAFETY..........................................................................2-126

2.8 Liquid Penetrant Inspection Safety...............................................................................................................2-1262.8.1 Safety Requirements......................................................................................................................................2-1262.8.2 General Precautions.......................................................................................................................................2-1262.8.3 Personal Protection Equipment .....................................................................................................................2-1262.8.4 Ventilation......................................................................................................................................................2-1262.8.5 Matting...........................................................................................................................................................2-1272.8.6 UV-A Hazards ...............................................................................................................................................2-1272.8.7 Hazards of Aerosol Cans ..............................................................................................................................2-127

3 MAGNETIC PARTICLE INSPECTION METHOD .....................................................................................................3-1

SECTION I MAGNETIC PARTICLE (MT) INSPECTION METHOD ....................................................................3-1

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3.1 General Capabilities of Magnetic Particle Inspection......................................................................................3-13.1.1 Introduction to Magnetic Particle Inspection (MPI) ........................................................................................3-13.1.2 Benefit of Magnetic Particle Inspection ...........................................................................................................3-13.1.3 Basic Concept of Magnetic Particle Inspection ...............................................................................................3-1

SECTION II MAGNETIC PARTICLE PRINCIPLES AND THEORY.....................................................................3-2

3.2 Principles and Theory of Magnetic Particle Inspection ...................................................................................3-23.2.1 Principles of Magnetization ..............................................................................................................................3-23.2.2 Basic Terminology ............................................................................................................................................3-23.2.3 Magnetic Field Characteristics..........................................................................................................................3-33.2.4 Currents Used to Generate Magnetic Fields ....................................................................................................3-93.2.5 Ferromagnetic Material Characteristics ..........................................................................................................3-10

SECTION III MAGNETIC PARTICLE INSPECTION EQUIPMENT ...................................................................3-14

3.3 Magnetic Particle Inspection Equipment and Materials ................................................................................3-143.3.1 Selection of Magnetic Particle Inspection Equipment ...................................................................................3-143.3.2 Categories of Magnetic Particle Inspection Equipment .................................................................................3-143.3.3 Inspection Equipment Accessories..................................................................................................................3-173.3.4 Special Purpose Equipment.............................................................................................................................3-173.3.5 Field Strength Measurement Devices .............................................................................................................3-193.3.6 Understanding and Selecting Magnetic Particle Inspection Materials ..........................................................3-22

SECTION IV MAGNETIC PARTICLE INSPECTION APPLICATIONS..............................................................3-28

3.4 Magnetic Particle Inspection Application Methods .......................................................................................3-283.4.1 Inspection Preparation .....................................................................................................................................3-283.4.2 Magnetic Particle Inspection Techniques .......................................................................................................3-303.4.3 Selecting a Magnetizing Current ....................................................................................................................3-323.4.4 Magnetic Field.................................................................................................................................................3-343.4.5 Field Strength Measurement Techniques........................................................................................................3-403.4.6 Methods of Particle Application .....................................................................................................................3-423.4.7 Wet Fluorescent Inspection Technique...........................................................................................................3-523.4.8 Portable Magnetic Particle Inspection ............................................................................................................3-533.4.9 Special Magnetization Techniques..................................................................................................................3-553.4.10 Multidirectional Magnetization .......................................................................................................................3-573.4.11 Demagnetization ..............................................................................................................................................3-583.4.12 Post Inspection Cleaning.................................................................................................................................3-653.4.13 Magnetic Rubber Inspection ...........................................................................................................................3-66

SECTION V MAGNETIC PARTICLE INSPECTION INTERPRETATIONS .......................................................3-77

3.5 Magnetic Particle Inspection Interpretation....................................................................................................3-773.5.1 Formation of Discontinuities and their Indications........................................................................................3-773.5.2 Definition of Terms.........................................................................................................................................3-793.5.3 Basic Steps of Inspection ................................................................................................................................3-793.5.4 Classes of Discontinuities ...............................................................................................................................3-853.5.5 Non-Relevant Indications ..............................................................................................................................3-1043.5.6 Interpretation and Elimination of Non-Relevant Indications .......................................................................3-1093.5.7 Methods of Recording MPI Indications .......................................................................................................3-109

SECTION VI PROCESS CONTROL OF MAGNETIC PARTICLE INSPECTION ............................................3-112

3.6 Magnetic Particle Process Control................................................................................................................3-1123.6.1 Purpose and Scope ........................................................................................................................................3-1123.6.2 General...........................................................................................................................................................3-1123.6.3 Causes of System Degradation .....................................................................................................................3-1123.6.4 Frequency of Process Control .......................................................................................................................3-1133.6.5 Evaluating the Magnetic Particle Process ....................................................................................................3-113

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3.6.6 Evaluating Equipment Effectiveness ............................................................................................................3-1133.6.7 Evaluating Material Effectiveness ................................................................................................................3-1163.6.8 Additional Tests for Water Baths .................................................................................................................3-1193.6.9 Disposition for Nonconformance Materials..................................................................................................3-1203.6.10 Magnetic Particle Process Checklist .............................................................................................................3-120

SECTION VII MAGNETIC PARTICLE INSPECTION EQUATIONS ................................................................3-122

3.7 Magnetic Particle Equations..........................................................................................................................3-1223.7.1 Rule-of-Thumb Formulas ..............................................................................................................................3-1223.7.2 Cross-Sectional Area .....................................................................................................................................3-1223.7.3 Calculating Coil Current ...............................................................................................................................3-123

SECTION VIII MAGNETIC PARTICLE INSPECTION SAFETY.......................................................................3-127

3.8 Magnetic Particle Safety ...............................................................................................................................3-1273.8.1 Safety Requirements......................................................................................................................................3-1273.8.2 General Precautions.......................................................................................................................................3-1273.8.3 Floor Matting.................................................................................................................................................3-1273.8.4 Wet Suspension Precautions .........................................................................................................................3-1273.8.5 Arcing Precautions ........................................................................................................................................3-1273.8.6 Head Stocks ...................................................................................................................................................3-1273.8.7 UV-A Hazards ...............................................................................................................................................3-1283.8.8 Hazards of Aerosol Cans ..............................................................................................................................3-1283.8.9 Magnetic Rubber Precautions .......................................................................................................................3-128

4 EDDY CURRENT INSPECTION METHOD................................................................................................................4-1

SECTION I EDDY CURRENT INSPECTION (ET) METHOD................................................................................4-1

4.1 General Capabilities of ET................................................................................................................................4-14.1.1 Introduction to Eddy Current Inspection ..........................................................................................................4-14.1.2 Definition of Eddy Current ...............................................................................................................................4-14.1.3 Inspection With Eddy Current ..........................................................................................................................4-14.1.4 Advantages of the Eddy Current Method.........................................................................................................4-14.1.5 Limitations of the Eddy Current Method .........................................................................................................4-24.1.6 Variables Affecting Eddy Currents...................................................................................................................4-24.1.7 Eddy Current Techniques..................................................................................................................................4-64.1.8 Field Application ...............................................................................................................................................4-6

SECTION II MATERIALS AND PROCESSES .........................................................................................................4-7

4.2 Materials and Processes ....................................................................................................................................4-74.2.1 Structure of Metals ............................................................................................................................................4-74.2.2 Mechanical Properties .......................................................................................................................................4-74.2.3 Electrical Conductivity ......................................................................................................................................4-74.2.4 Mechanical Properties of Pure Metals..............................................................................................................4-74.2.5 Alloys.................................................................................................................................................................4-84.2.6 Heat Treatment ..................................................................................................................................................4-84.2.7 Measurement of Mechanical Properties............................................................................................................4-9

SECTION III EDDY CURRENT PRINCIPLES AND THEORY............................................................................4-10

4.3 Principles and Theory of Eddy Current Inspection........................................................................................4-104.3.1 Induction of Eddy Currents.............................................................................................................................4-104.3.2 Primary Electromagnetic Field........................................................................................................................4-104.3.3 Secondary Electromagnetic Field....................................................................................................................4-104.3.4 Depth of Penetration........................................................................................................................................4-104.3.5 Impedance ........................................................................................................................................................4-114.3.6 Sensitivity ........................................................................................................................................................4-11

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4.3.7 Resolution ........................................................................................................................................................4-114.3.8 Measurement of Resistivity.............................................................................................................................4-114.3.9 Measurement of Conductivity.........................................................................................................................4-124.3.10 Overview of Signal Detection, Processing, and Display ...............................................................................4-124.3.11 Impedance Diagrams .......................................................................................................................................4-174.3.12 Impedance Plane Analysis ..............................................................................................................................4-234.3.13 Phase Lag at Depth .........................................................................................................................................4-264.3.14 Effects of Inspection Conditions on Eddy Currents ......................................................................................4-27

SECTION IV EDDY CURRENT EQUIPMENT ......................................................................................................4-30

4.4 ET Equipment..................................................................................................................................................4-304.4.1 Components of an Eddy Current System .......................................................................................................4-304.4.2 Eddy Current Subsystems ...............................................................................................................................4-314.4.3 Functions of the Eddy Current Instrument .....................................................................................................4-344.4.4 Digital Equipment............................................................................................................................................4-374.4.5 Recorders .........................................................................................................................................................4-374.4.6 Mechanical Scanners .......................................................................................................................................4-384.4.7 Fixtures and Guides.........................................................................................................................................4-384.4.8 Special Processes.............................................................................................................................................4-384.4.9 Electromagnetic Techniques Closely Related to Eddy Current.....................................................................4-394.4.10 Application of Advanced Techniques.............................................................................................................4-39

SECTION V APPLICATION OF ET ........................................................................................................................4-40

4.5 General.............................................................................................................................................................4-404.5.1 Null Point.........................................................................................................................................................4-404.5.2 Parameters........................................................................................................................................................4-404.5.3 Modulation Analysis........................................................................................................................................4-424.5.4 Frequency Response ........................................................................................................................................4-434.5.5 Inspection of Fastener Holes...........................................................................................................................4-454.5.6 Fastener Hole Inspection Equipment ..............................................................................................................4-464.5.7 Probe Fit ..........................................................................................................................................................4-494.5.8 Probe Taping....................................................................................................................................................4-504.5.9 Lift-Off Compensation for Bolt-Hole Inspection...........................................................................................4-524.5.10 Standardization Settings ..................................................................................................................................4-524.5.11 Scan Speed and Pattern...................................................................................................................................4-524.5.12 Probe Alignment..............................................................................................................................................4-524.5.13 Probe to Edge Spacing ....................................................................................................................................4-534.5.14 Bolt Hole Eddy Current Signal Interpretation................................................................................................4-544.5.15 Fastener Holes Non-Removable Fasteners .....................................................................................................4-584.5.16 Fillets and Rounded Corners...........................................................................................................................4-584.5.17 Corrosion..........................................................................................................................................................4-594.5.18 Field Measurement of Conductivity ...............................................................................................................4-614.5.19 Effects of Variations in Material Properties...................................................................................................4-624.5.20 Effects of Variations in Test Conditions ........................................................................................................4-634.5.21 Flaw Detection.................................................................................................................................................4-644.5.22 Lift-Off Effects ................................................................................................................................................4-674.5.23 Lift-Off Compensation Methods.....................................................................................................................4-684.5.24 Effects of Crack Location on Detectability....................................................................................................4-724.5.25 Effects of Scanning Techniques on Detection ...............................................................................................4-744.5.26 Reference Standards for Cracks......................................................................................................................4-754.5.27 Thickness Measurement ..................................................................................................................................4-824.5.28 Measurement of Total Metal Thickness .........................................................................................................4-834.5.29 Application of Conductive Coating Measurement .........................................................................................4-854.5.30 Measurement of Nonconductive Coatings......................................................................................................4-86

SECTION VI INTERPRETING EDDY CURRENT SIGNALS...............................................................................4-88

4.6 ET Interpretation..............................................................................................................................................4-88

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4.6.1 Flaw Detection.................................................................................................................................................4-884.6.2 Effect of Scan Rate and Pattern......................................................................................................................4-894.6.3 Openings, Large Holes, and Cutouts ..............................................................................................................4-894.6.4 Conductivity Measurement..............................................................................................................................4-90

SECTION VII EDDY CURRENT PROCESS CONTROL.......................................................................................4-92

4.7 ET Process Control..........................................................................................................................................4-924.7.1 General.............................................................................................................................................................4-924.7.2 Specific ............................................................................................................................................................4-92

SECTION VIII EDDY CURRENT EQUATIONS....................................................................................................4-93

4.8 Eddy Current Equations ..................................................................................................................................4-934.8.1 Resistance ......................................................................................................................................................4-1014.8.2 Inductance ......................................................................................................................................................4-1034.8.3 Fill Factor ......................................................................................................................................................4-1044.8.4 Inductive Reactance and Capacitive Reactance ...........................................................................................4-1044.8.5 Impedance ......................................................................................................................................................4-1054.8.6 Permeability ...................................................................................................................................................4-1054.8.7 Depth of Penetration ()................................................................................................................................4-1064.8.8 Limit Frequency, f g. and the ''Similarity'' Law ...........................................................................................4-1074.8.9 Characteristic Frequency ...............................................................................................................................4-1074.8.10 Coverage of Coil or Effective Coil Diameter ..............................................................................................4-1074.8.11 Calculating Flaw Frequency for Setting Filters ...........................................................................................4-1074.8.12 Measurement of Conductivity.......................................................................................................................4-107

SECTION IX EDDY SAFETY ................................................................................................................................4-108

4.9 Eddy Current Safety ......................................................................................................................................4-1084.9.1 Safety Requirements......................................................................................................................................4-1084.9.2 General Precautions.......................................................................................................................................4-108

5 ULTRASONIC INSPECTION METHOD .....................................................................................................................5-1

SECTION I GENERAL CAPABILITIES OF ULTRASONIC (UT) INSPECTION.................................................5-1

5.1 Introduction........................................................................................................................................................5-15.1.1 Introduction to Ultrasonic Inspection ...............................................................................................................5-15.1.2 Development of Ultrasonics..............................................................................................................................5-15.1.3 Ultrasonic Testing..............................................................................................................................................5-1

SECTION II PRINCIPLES AND THEORY OF ULTRASONIC INSPECTION......................................................5-2

5.2 Introduction........................................................................................................................................................5-25.2.1 Characteristics of Ultrasonic Energy ................................................................................................................5-25.2.2 Generation and Receiving of Ultrasonic Vibrations ........................................................................................5-25.2.3 Modes of Ultrasonic Vibration .........................................................................................................................5-35.2.4 Refraction and Mode Conversion .....................................................................................................................5-65.2.5 Ultrasonic Inspection Variables ........................................................................................................................5-75.2.6 Sound Beam Characteristics..............................................................................................................................5-8

SECTION III ULTRASONIC INSPECTION EQUIPMENT AND MATERIALS .................................................5-12

5.3 Introduction......................................................................................................................................................5-125.3.1 Ultrasonic Instruments.....................................................................................................................................5-125.3.2 Transducers ......................................................................................................................................................5-215.3.3 Specialized Transducers ..................................................................................................................................5-255.3.4 Wedges and Shoes...........................................................................................................................................5-275.3.5 Couplants .........................................................................................................................................................5-35

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5.3.6 Inspection Standards........................................................................................................................................5-365.3.7 Bonded Structure Reference Standards ..........................................................................................................5-375.3.8 Thickness Measurement Equipment ...............................................................................................................5-38

SECTION IV ULTRASONIC INSPECTION APPLICATION ................................................................................5-40

5.4 Introduction......................................................................................................................................................5-405.4.1 Guidelines for Inspector Familiarization ........................................................................................................5-405.4.2 Basic Ultrasonic Inspection.............................................................................................................................5-405.4.3 Ultrasonic Reflections .....................................................................................................................................5-415.4.4 Data Presentation Methods..............................................................................................................................5-425.4.5 Relationship of a Scan Waveform Display to Distance.................................................................................5-445.4.6 Common Inspection Techniques.....................................................................................................................5-445.4.7 Ultrasonic Technique Development................................................................................................................5-495.4.8 Distance Amplitude Correction (DAC) Curve ...............................................................................................5-515.4.9 Attenuation Correction (Transfer)...................................................................................................................5-515.4.10 Inspection of Bonded Structures.....................................................................................................................5-575.4.11 Thickness Measurement ..................................................................................................................................5-585.4.12 Calibration and Thickness Measurement........................................................................................................5-59

SECTION V ULTRASONIC INSPECTION INTERPRETATION..........................................................................5-60

5.5 Introduction......................................................................................................................................................5-605.5.1 Evaluation of Discontinuity Indications .........................................................................................................5-605.5.2 Types of Discontinuity Indications.................................................................................................................5-605.5.3 Test Part Variables ..........................................................................................................................................5-675.5.4 Discontinuity Variables ...................................................................................................................................5-705.5.5 Inspection Coverage of Bonded Structures ....................................................................................................5-705.5.6 Inspection Methods for Bonded Structures ....................................................................................................5-725.5.7 Techniques Associated With Instruments Dedicated to Bond Inspection.....................................................5-805.5.8 Thickness Measurement Test Part Preparation ..............................................................................................5-845.5.9 Thickness Measurement Considerations.........................................................................................................5-85

SECTION VI ULTRASONIC INSPECTION PROCESS CONTROLS...................................................................5-86

5.6 Introduction......................................................................................................................................................5-865.6.1 Ultrasonic Process Control Requirements ......................................................................................................5-865.6.2 Reference Standard Configuration ..................................................................................................................5-865.6.3 System (Equipment) Checks ...........................................................................................................................5-905.6.4 Transducer Verifications .................................................................................................................................5-91

SECTION VII ULTRASONIC INSPECTION EQUATIONS ..................................................................................5-93

5.7 Introduction......................................................................................................................................................5-935.7.1 General.............................................................................................................................................................5-935.7.2 Snells Law......................................................................................................................................................5-935.7.3 Determining the Angle of Incidence in Plastic to Generate 45-Degree Shear Wave in Aluminum ...........5-935.7.4 Wavelength ......................................................................................................................................................5-935.7.5 Near Field ........................................................................................................................................................5-945.7.6 Beam Spread....................................................................................................................................................5-945.7.7 Calculating Acoustic Impedance.....................................................................................................................5-955.7.8 Thickness Measurement Correlation Factor ...................................................................................................5-96

SECTION VIII ULTRASONIC INSPECTION SAFETY.........................................................................................5-98

5.8 Introduction......................................................................................................................................................5-985.8.1 Safety Requirements........................................................................................................................................5-985.8.2 General Precautions.........................................................................................................................................5-985.8.3 Ultrasonic Inspection.......................................................................................................................................5-98

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6 RADIOGRAPHIC INSPECTION METHOD.................................................................................................................6-1

SECTION I RADIOGRAPHIC (RT) INSPECTION METHOD ................................................................................6-1

6.1 General Capabilities of Radiographic Inspection.............................................................................................6-16.1.1 Introduction to Radiographic Inspection ..........................................................................................................6-16.1.2 History of X- and Gamma Radiation ...............................................................................................................6-26.1.3 Factors of Radiographic Inspection ..................................................................................................................6-36.1.4 The Physics of X-rays.......................................................................................................................................6-46.1.5 Properties of X- and Gamma Radiation ...........................................................................................................6-66.1.6 Differential Absorption of Radiation in Matter................................................................................................6-66.1.7 Exposure of Film to Radiation..........................................................................................................................6-86.1.8 When to use Radiography.................................................................................................................................6-96.1.9 Unique Properties of Gamma Radiation...........................................................................................................6-9

SECTION II PRINCIPLES AND THEORY OF RADIOGRAPHIC INSPECTION...............................................6-11

6.2 How X-rays Are Produced..............................................................................................................................6-116.2.1 Generating X-Radiation...................................................................................................................................6-116.2.2 Type of Radiation Produced by a Tube Head................................................................................................6-126.2.3 Effects of Voltage and Amperage on X-ray Production................................................................................6-136.2.4 X-ray Generators .............................................................................................................................................6-146.2.5 Intensity and Distribution of an X-ray Beam.................................................................................................6-166.2.6 Interaction of Radiation With Matter .............................................................................................................6-196.2.7 Radiation Energy .............................................................................................................................................6-236.2.8 Scatter Radiation..............................................................................................................................................6-246.2.9 Material Contrast .............................................................................................................................................6-256.2.10 Understanding Radiographic Film ..................................................................................................................6-256.2.11 Fundamentals of Digital Radiography ............................................................................................................6-30

SECTION III RADIOGRAPHIC EQUIPMENT .......................................................................................................6-34

6.3 Radiographic Inspection Equipment ...............................................................................................................6-346.3.1 Types of X-ray Generators..............................................................................................................................6-346.3.2 Types of X-ray Tubes .....................................................................................................................................6-346.3.3 Considerations in Choosing Equipment..........................................................................................................6-346.3.4 Considerations When Operating X-ray Equipment........................................................................................6-366.3.5 Standard Industrial X-ray Equipment in the DoD .........................................................................................6-386.3.6 Isotope Source Equipment ..............................................................................................................................6-386.3.7 Radiographic Film ...........................................................................................................................................6-406.3.8 Film Holders, Film Cassettes, and Radiographic Screens .............................................................................6-456.3.9 Quality Indicators ............................................................................................................................................6-496.3.10 Radiation Monitoring Devices and Instruments .............................................................................................6-516.3.11 Radiographic Processing Equipment ..............................................................................................................6-556.3.12 Film Evaluation Equipment ............................................................................................................................6-566.3.13 Digital Radiographic Viewing, Storage, Archival, and Printing Systems.....................................................6-56

SECTION IV APPLICATION OF RADIOGRAPHIC INSPECTION .....................................................................6-57

6.4 Effective Radiographic Inspections ................................................................................................................6-576.4.1 Introduction......................................................................................................................................................6-576.4.2 Factors Affecting Image Quality ....................................................................................................................6-576.4.3 Radiographic Sensitivity..................................................................................................................................6-706.4.4 Improving Radiographic Sensitivity ...............................................................................................................6-746.4.5 Darkroom Design ............................................................................................................................................6-806.4.6 Radiographic Film ...........................................................................................................................................6-836.4.7 Film Handling Problems .................................................................................................................................6-846.4.8 Preparation for Manual Processing.................................................................................................................6-886.4.9 Storage of Radiographs ...................................................................................................................................6-88

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6.4.10 Processing Chemicals ......................................................................................................................................6-896.4.11 Processing Radiographic Film ........................................................................................................................6-916.4.12 Manual Film Processing Procedure ................................................................................................................6-996.4.13 Automatic Film Processing ...........................................................................................................................6-1026.4.14 Silver Recovery .............................................................................................................................................6-1056.4.15 Film Reproduction Technique.......................................................................................................................6-1056.4.16 Film Artifacts.................................................................................................................................................6-1066.4.17 Special Radiographic Techniques .................................................................................................................6-1086.4.18 Digital Radiographic Techniques..................................................................................................................6-116

SECTION V INTERPRETATION OF RADIOGRAPHIC INSPECTION.............................................................6-117

6.5 Radiographic Interpretation...........................................................................................................................6-1176.5.1 General...........................................................................................................................................................6-1176.5.2 Radiographic Image Quality .........................................................................................................................6-1176.5.3 Sensitivity ......................................................................................................................................................6-1176.5.4 Definition or Detail .......................................................................................................................................6-1176.5.5 Density ...........................................................................................................................................................6-1196.5.6 Contrast ..........................................................................................................................................................6-1206.5.7 Fog .................................................................................................................................................................6-1216.5.8 Distortion and Magnification ........................................................................................................................6-1216.5.9 Kilovoltage and Processing...........................................................................................................................6-1216.5.10 Viewing Radiographs ....................................................................................................................................6-1216.5.11 Reading (Interpreting) Radiographs..............................................................................................................6-1246.5.12 Typical Use of Radiography .........................................................................................................................6-1246.5.13 Castings..........................................................................................................................................................6-1246.5.14 Casting Defects..............................................................................................................................................6-1256.5.15 Welds .............................................................................................................................................................6-1336.5.16 Welding Defects and Conditions ..................................................................................................................6-1346.5.17 In-Service Inspections ...................................................................................................................................6-1506.5.18 Assemblies .....................................................................................................................................................6-1516.5.19 Radiographic Standards.................................................................................................................................6-1516.5.20 Digital Radiographic Image Analysis ...........................................................................................................6-152

SECTION VI PROCESS CONTROL OF RADIOGRAPHIC INSPECTION........................................................6-154

6.6 Radiographic Process Control .......................................................................................................................6-1546.6.1 Scope and Purpose ........................................................................................................................................6-1546.6.2 Radiographic Process Control Requirements ...............................................................................................6-1546.6.3 Process Control in the Darkroom .................................................................................................................6-1546.6.4 Controlling the Development Process ..........................................................................................................6-155

SECTION VII RADIOGRAPHIC INSPECTION EQUATIONS ...........................................................................6-158

6.7 Radiographic Equations.................................................................................................................................6-1586.7.1 General...........................................................................................................................................................6-1586.7.2 Exposure Factor.............................................................................................................................................6-1586.7.3 Inverse Square Law.......................................................................................................................................6-1586.7.4 Source-to-Film Distance (SFD) ....................................................................................................................6-1596.7.5 Film Density ..................................................................................................................................................6-1596.7.6 Logarithms for Density and Exposure Calculations ....................................................................................6-1606.7.7 Material Contrast Factor................................................................................................................................6-1636.7.8 Image Unsharpness........................................................................................................................................6-1636.7.9 Heel Effect.....................................................................................................................................................6-164

SECTION VIII AIR FORCE RADIOGRAPHIC INSPECTION SAFETY ...........................................................6-166

6.8 Scope and Purpose of Radiation Protection .................................................................................................6-1666.8.1 General...........................................................................................................................................................6-1666.8.2 Responsibilities ..............................................................................................................................................6-166

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6.8.3 Qualifications and Training of Industrial Radiographers.............................................................................6-1696.8.4 Radiation Protection ......................................................................................................................................6-1726.8.5 Industrial Radiographic Operations ..............................................................................................................6-1816.8.6 Industrial Radiographic Installation Classifications .....................................................................................6-1826.8.7 Utilization Log...............................................................................................................................................6-1916.8.8 Radiation Areas and Facilities ......................................................................................................................6-192

SECTION IX ARMY RADIOGRAPHIC INSPECTION SAFETY .......................................................................6-197

6.9 Scope and Purpose of Radiation Protection .................................................................................................6-1976.9.1 General...........................................................................................................................................................6-1976.9.2 Responsibilities ..............................................................................................................................................6-1976.9.3 Qualifications of Industrial Radiographers...................................................................................................6-2016.9.4 Industrial Radiographic Safety Training.......................................................................................................6-2016.9.5 Radiation Protection ......................................................................................................................................6-2056.9.6 Industrial Radiographic Operations ..............................................................................................................6-2166.9.7 Industrial Radiographic Installation Classifications .....................................................................................6-2166.9.8 Mandatory Operating Procedures..................................................................................................................6-2226.9.9 NDI Facility Design and Modification.........................................................................................................6-228

SECTION X COMPUTED RADIOGRAPHY.........................................................................................................6-232

6.10 General Capabilities of Computed Radiography..........................................................................................6-2326.10.1 Introduction to Computed Radiography .......................................................................................................6-2326.10.2 Computed Radiography System....................................................................................................................6-2346.10.3 Display Conversion .......................................................................................................................................6-2406.10.4 Point-to-Point Pre-Processing........................................................................................................................6-2406.10.5 Image Filtering ..............................................................................................................................................6-2406.10.6 Spatial Re-Sampling ......................................................................................................................................6-2416.10.7 Gray Mapping................................................................................................................................................6-2426.10.8 Adding Annotations and Analysis ................................................................................................................6-2446.10.9 Viewing Room Ambient Light .....................................................................................................................6-2446.10.10 Process Controls ............................................................................................................................................6-2446.10.11 Tools Used in Image Interpretation With the Software...............................................................................6-2456.10.12 Digital Image, Data Archival and Retention................................................................................................6-2456.10.13 Computed Radiography Terminology...........................................................................................................6-246

7 LASER SHEAROGRAPHY ...........................................................................................................................................7-1

SECTION I LASER SHEAROGRAPHY (ST) INSPECTION METHOD.................................................................7-1

7.1 General Capabilities of Laser Shearography Inspection ..................................................................................7-17.1.1 Introduction to Laser Shearography Inspection................................................................................................7-17.1.2 Background of Laser Shearography Inspection................................................................................................7-17.1.3 Why Use Laser Shearography Inspection ........................................................................................................7-17.1.4 Consideration for Laser Shearography Inspection ...........................................................................................7-17.1.5 Advantages of Laser Shearography Inspection ................................................................................................7-27.1.6 Disadvantages of Laser Shearography Inspection............................................................................................7-3

SECTION II PRINCIPLES AND THEORY OF LASER SHEAROGRAPHY INSPECTION.................................7-4

7.2 Principles and Theory of Laser Shearography Inspection ...............................................................................7-47.2.1 Principles of Shearography ...............................................................................................................................7-47.2.2 Basic Terminology ............................................................................................................................................7-67.2.3 Stressing Methods..............................................................................................................................................7-9

SECTION III LASER SHEAROGRAPHY EQUIPMENT .......................................................................................7-11

7.3 Laser Shearography Inspection Equipment and Materials.............................................................................7-117.3.1 Selection of Laser Shearography Inspection Equipment ...............................................................................7-11

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7.3.2 Components of the Laser Shearography Systems ..........................................................................................7-11

SECTION IV APPLICATION OF LASER SHEAROGRAPHY INSPECTION.....................................................7-12

7.4 Application of Laser Shearography Inspection ..............................................................................................7-127.4.1 General.............................................................................................................................................................7-127.4.2 Basic Inspection Process .................................................................................................................................7-127.4.3 Definition of Defect Indication.......................................................................................................................7-22

SECTION V INTERPRETATION OF LASER SHEAROGRAPHY INSPECTION ..............................................7-23

7.5 Laser Shearography Inspection Image Interpretation.....................................................................................7-237.5.1 Image Interpretation and Analysis ..................................................................................................................7-237.5.2 Shearography NDI Test Standards..................................................................................................................7-24

SECTION VI PROCESS CONTROL OF LASER SHEAROGRAPHY ..................................................................7-29

7.6 Laser Shearography Process Control ..............................................................................................................7-297.6.1 General.............................................................................................................................................................7-29

SECTION VII LASER SHEAROGRAPHY SAFETY..............................................................................................7-30

7.7 Laser Shearography Safety..............................................................................................................................7-307.7.1 Safety Requirements........................................................................................................................................7-307.7.2 Laser Safety ........................