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T.O. 33B-1-1 NAVAIR 01-1A-16 TM 1-1500-335-23TECHNICAL MANUAL

NONDESTRUCTIVE INSPECTION METHODS, BASIC THEORY(ATOS) THIS MANUAL SUPERSEDES T.O. 33B-1-1, DATED 1 JANUARY 2005, AND ALL SUBSEQUENT CHANGES. THIS MANUAL HAS BEEN EXTENSIVELY REWRITTEN; THEREFORE, REVISION BARS HAVE BEEN OMITTED.

ARMY PERSONNEL: NAVY PERSONNEL:

Wherever the text of this manual refers to Air Force technical orders for supportive information, refer to the comparable Army documents. OPNAV instruction 4790.2 and weapon system specific manuals take precedence over this manual.

DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. PA Case Number SPR50014. Submit recommended changes or problems with this Technical Order to 558 CBSS/GBHA.

Published under Authority of the Secretary of the Air Force

15 JUNE 2007

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T.O. 33B-1-1INSERT 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 DESTROY SUPERSEDED PAGES.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 June 2007

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T.O. 33B-1-1

TABLE OF CONTENTSChapter Page

INTRODUCTION............................................................................................................................................................ xix SAFETY SUMMARY..................................................................................................................................................... xxi 1 NONDESTRUCTIVE INSPECTION METHODS, GENERAL INFORMATION ......................................................1-1 SECTION I NONDESTRUCTIVE INSPECTION (NDI) METHODS ......................................................................1-1 1.1 1.1.1 1.1.2 1.1.3 1.1.4 Why We Do Nondestructive Inspection (NDI)................................................................................................1-1 Nondestructive Inspection Data ........................................................................................................................1-1 Structural Management Programs.....................................................................................................................1-1 Mechanisms for Using NDI Data .....................................................................................................................1-1 Tools for Gathering NDI Data..........................................................................................................................1-2

SECTION II PERSONNEL TRAINING/QUALIFICATION/CERTIFICATION ......................................................1-3 1.2 1.2.1 1.2.2 1.2.3 1.2.4 1.2.5 Personnel Training/Qualification/Certification .................................................................................................1-3 Training Introduction.........................................................................................................................................1-3 Training Requirements ......................................................................................................................................1-3 Certification Requirements................................................................................................................................1-3 Physical Requirements ......................................................................................................................................1-3 Requirement for Special Task Certification and Recurring Training..............................................................1-3

SECTION III REPORTING NEW OR IMPROVED NDI TECHNIQUES ...............................................................1-5 1.3 1.3.1 1.3.2 1.3.3 1.3.4 1.3.5 1.3.6 Reporting New/Improved Nondestructive Inspection Techniques ..................................................................1-5 Need for Reporting New and Improved Techniques .......................................................................................1-5 Authority ............................................................................................................................................................1-5 AFTO Form 242................................................................................................................................................1-5 Scope..................................................................................................................................................................1-5 Responsibilities for Updating Techniques ........................................................................................................1-5 AFTO Form 242 Entries ...................................................................................................................................1-6

SECTION IV NDI EQUIPMENT ................................................................................................................................1-9 1.4 1.4.1 1.4.2 1.4.3 Procuring NDI Equipment (AIR FORCE Only) ..............................................................................................1-9 Centrally Procured NDI Equipment..................................................................................................................1-9 Weapon System Specific/Special Purpose Equipment.....................................................................................1-9 Local Purchase Equipment................................................................................................................................1-9

SECTION V PROCESS CONTROL..........................................................................................................................1-10 1.5 1.5.1 1.5.2 1.5.3 1.5.4 1.5.5 Process Control................................................................................................................................................1-10 Reason for Controlling the Process ................................................................................................................1-10 Scope of Process Control ................................................................................................................................1-10 Process Control Documentation Requirements ..............................................................................................1-12 Establishing a Documentation Method...........................................................................................................1-12 Suggested Documentation Method .................................................................................................................1-12

SECTION VI LABORATORY INFORMATION .....................................................................................................1-13 1.6 General Laboratory Information .....................................................................................................................1-13

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T.O. 33B-1-1 1.6.1 1.6.2 1.6.3 1.6.4 2 Constructing a Nondestructive Inspection Laboratory ...................................................................................1-13 Building Requirements ....................................................................................................................................1-13 Electrical and Mechanical Requirements........................................................................................................1-14 Room Identification.........................................................................................................................................1-15

LIQUID PENETRANT INSPECTION METHOD ........................................................................................................2-1 SECTION I LIQUID PENETRANT INSPECTION METHOD .................................................................................2-1 2.1 2.1.1 2.1.2 2.1.3 2.1.4 2.1.5 2.1.6 2.1.7 2.1.8 2.1.9 2.1.10 2.1.11 2.1.12 General Capabilities of Liquid Penetrant Inspection .......................................................................................2-1 Introduction to Liquid Penetrant Inspection.....................................................................................................2-1 Background of Liquid Penetrant Inspection.....................................................................................................2-1 Why Use Liquid Penetrant Inspection..............................................................................................................2-1 Limitations of Liquid Penetrant Inspection ......................................................................................................2-1 Advantages of Liquid Penetrant Inspection......................................................................................................2-2 Disadvantages of Liquid Penetrant Inspection .................................................................................................2-2 Basic Penetrant Inspection Process...................................................................................................................2-3 Personnel Requirements ....................................................................................................................................2-4 Understanding Penetrant Classification and Processes ....................................................................................2-4 Qualification of Penetrant Material ..................................................................................................................2-9 Qualification of Penetrant Sensitivity...............................................................................................................2-9 Penetrant Material Performance........................................................................................................................2-9

SECTION II PRINCIPLES AND THEORY OF LIQUID PENETRANT INSPECTION.......................................2-11 2.2 2.2.1 2.2.2 2.2.3 2.2.4 2.2.5 2.2.6 2.2.7 2.2.8 2.2.9 2.2.10 2.2.11 Principles and Theory of Liquid Penetrant Inspection ..................................................................................2-11 General.............................................................................................................................................................2-11 Characteristics of a Penetrant..........................................................................................................................2-11 Mechanisms of Penetrant Action ....................................................................................................................2-11 How Liquid Penetrant Enters Discontinuities ................................................................................................2-17 Mechanisms and Principles of Penetrant Removal ........................................................................................2-17 Mechanisms of Developer Action ..................................................................................................................2-21 Cleaning and Surface Preparation...................................................................................................................2-22 Surface Conditions Affecting Penetrant Inspection .......................................................................................2-22 Contaminants and Soils...................................................................................................................................2-22 Coatings ...........................................................................................................................................................2-27 Effects of Surface Deformation, Wear, and Surface Roughness on Penetrant Inspection ...........................2-29

SECTION III LIQUID PENETRANT INSPECTION EQUIPMENT.......................................................................2-31 2.3 2.3.1 2.3.2 2.3.3 2.3.4 2.3.5 2.3.6 2.3.7 Equipment ........................................................................................................................................................2-31 General.............................................................................................................................................................2-31 Portable Equipment .........................................................................................................................................2-31 Stationary Inspection Equipment - General Purpose .....................................................................................2-31 Small Parts Inspection Systems ......................................................................................................................2-31 Automated Inspection Systems .......................................................................................................................2-31 Inspection Lamps.............................................................................................................................................2-31 Process Control Equipment.............................................................................................................................2-35

SECTION IV LIQUID PENETRANT APPLICATION METHODS .......................................................................2-36 2.4 2.4.1 2.4.2 2.4.3 2.4.4 2.4.5 2.4.6 2.4.7 Application Method.........................................................................................................................................2-36 General.............................................................................................................................................................2-36 Basic Penetrant Processes ...............................................................................................................................2-36 Pre-Testing.......................................................................................................................................................2-41 Pre-Cleaning Preformed by NDI Personnel ...................................................................................................2-41 Penetrant Application ......................................................................................................................................2-42 Temperature Limitations .................................................................................................................................2-44 Penetrant Dwell ...............................................................................................................................................2-47

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T.O. 33B-1-1 2.4.8 2.4.9 2.4.10 2.4.11 2.4.12 2.4.13 Penetrant Removal...........................................................................................................................................2-53 Water Washing/Rinsing Technique ................................................................................................................2-64 Drying ..............................................................................................................................................................2-65 Application of Developers ..............................................................................................................................2-67 Post-Cleaning After Penetrant Inspection.......................................................................................................2-76 Protection of Parts Following Penetrant Inspection .......................................................................................2-77

SECTION V INTERPRETATION OF LIQUID PENETRANT INSPECTION ......................................................2-78 2.5 2.5.1 2.5.2 2.5.3 2.5.4 2.5.5 2.5.6 Interpretation of Indications ............................................................................................................................2-78 General.............................................................................................................................................................2-78 Importance of Understanding the Interpretation Process ...............................................................................2-78 Personnel Requirements ..................................................................................................................................2-78 Lighting............................................................................................................................................................2-78 Inspection Conditions ......................................................................................................................................2-83 Evaluating Indications .....................................................................................................................................2-83

SECTION VI PROCESS CONTROL OF LIQUID PENETRANT INSPECTION..................................................2-92 2.6 2.6.1 2.6.2 2.6.3 2.6.4 2.6.5 2.6.6 2.6.7 2.6.8 2.6.9 2.6.10 Liquid Penetrant Process Control ...................................................................................................................2-92 General.............................................................................................................................................................2-92 Need for Process Quality ................................................................................................................................2-92 Why Test New Materials ................................................................................................................................2-92 Why Test In-Use Materials.............................................................................................................................2-92 Causes of Material Degradation......................................................................................................................2-92 Establishing Work Center Process Control Intervals .....................................................................................2-93 Process Control Equipment.............................................................................................................................2-93 Process Control Requirement..........................................................................................................................2-96 Control of New Materials .............................................................................................................................2-101 Testing In-Use Materials...............................................................................................................................2-102

SECTION VII SPECIAL PURPOSE LIQUID PENETRANTS .............................................................................2-118 2.7 2.7.1 2.7.2 2.7.3 2.7.4 2.7.5 2.7.6 2.7.7 2.7.8 2.7.9 Special Purpose Liquid Penetrant .................................................................................................................2-118 General...........................................................................................................................................................2-118 Liquid Oxygen (LOX) Compatible Penetrants.............................................................................................2-118 Low Sulfur, Low Chlorine Penetrant Systems.............................................................................................2-119 High Temperature Penetrant Materials.........................................................................................................2-119 Dye Precipitation Penetrant Systems ............................................................................................................2-119 Reversed Fluorescence Method ....................................................................................................................2-119 Thixotropic Penetrant ....................................................................................................................................2-120 Dilution Expansion Developers ....................................................................................................................2-120 Plastic-Film Developers ................................................................................................................................2-120

SECTION VIII LIQUID PENETRANT INSPECTION SAFETY..........................................................................2-121 2.8 2.8.1 2.8.2 2.8.3 2.8.4 2.8.5 2.8.6 3 Liquid Penetrant Inspection Safety...............................................................................................................2-121 Safety Requirements......................................................................................................................................2-121 General Precautions.......................................................................................................................................2-121 Personal Protection Equipment .....................................................................................................................2-121 Ventilation......................................................................................................................................................2-121 Matting...........................................................................................................................................................2-122 UV-A (Black Light) Hazards........................................................................................................................2-122

MAGNETIC PARTICLE INSPECTION METHOD .....................................................................................................3-1 SECTION I MAGNETIC PARTICLE INSPECTION METHOD ..............................................................................3-1 3.1 3.1.1 General Capabilities of Magnetic Particle Inspection......................................................................................3-1 Introduction to Magnetic Particle Inspection (MPI) ........................................................................................3-1 iii

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T.O. 33B-1-1 3.1.2 3.1.3 Benefit of Magnetic Particle Inspection ...........................................................................................................3-1 Basic Concept of Magnetic Particle Inspection ...............................................................................................3-1

SECTION II MAGNETIC PARTICLE PRINCIPLES AND THEORY.....................................................................3-2 3.2 3.2.1 3.2.2 3.2.3 3.2.4 3.2.5 Principles and Theory of Magnetic Particle Inspection ...................................................................................3-2 Principles of Magnetization ..............................................................................................................................3-2 Basic Terminology ............................................................................................................................................3-2 Magnetic Field Characteristics..........................................................................................................................3-3 Currents Used to Generate Magnetic Fields ....................................................................................................3-9 Ferromagnetic Material Characteristics ..........................................................................................................3-10

SECTION III MAGNETIC PARTICLE INSPECTION EQUIPMENT ...................................................................3-14 3.3 3.3.1 3.3.2 3.3.3 3.3.4 3.3.5 3.3.6 Magnetic Particle Inspection Equipment and Materials ................................................................................3-14 Selection of Magnetic Particle Inspection Equipment ...................................................................................3-14 Categories of Magnetic Particle Inspection Equipment .................................................................................3-14 Inspection Equipment Accessories..................................................................................................................3-17 Special Purpose Equipment.............................................................................................................................3-17 Field Strength Measurement Devices .............................................................................................................3-18 Understanding and Selecting Magnetic Particle Inspection Materials ..........................................................3-20

SECTION IV MAGNETIC PARTICLE INSPECTION APPLICATIONS ..............................................................3-27 3.4 3.4.1 3.4.2 3.4.3 3.4.4 3.4.5 3.4.6 3.4.7 3.4.8 3.4.9 3.4.10 3.4.11 3.4.12 3.4.13 Magnetic Particle Inspection Application Methods .......................................................................................3-27 Inspection Preparation .....................................................................................................................................3-27 Magnetic Particle Inspection Techniques .......................................................................................................3-29 Selecting a Magnetizing Current ....................................................................................................................3-30 Magnetic Field.................................................................................................................................................3-33 Field Strength Measurement Techniques........................................................................................................3-39 Methods of Particle Application .....................................................................................................................3-41 Wet Fluorescent Inspection Technique...........................................................................................................3-50 Portable Magnetic Particle Inspection ............................................................................................................3-51 Special Magnetization Techniques..................................................................................................................3-53 Multidirectional Magnetization .......................................................................................................................3-55 Demagnetization ..............................................................................................................................................3-55 Post Inspection Cleaning.................................................................................................................................3-62 Magnetic Rubber Inspection ...........................................................................................................................3-63

SECTION V MAGNETIC PARTICLE INSPECTION INTERPRETATIONS .......................................................3-73 3.5 3.5.1 3.5.2 3.5.3 3.5.4 3.5.5 3.5.6 3.5.7 Magnetic Particle Inspection Interpretation....................................................................................................3-73 Formation of Discontinuities and their Indications........................................................................................3-73 Definition of Terms.........................................................................................................................................3-75 Basic Steps of Inspection ................................................................................................................................3-75 Classes of Discontinuities ...............................................................................................................................3-80 Non-Relevant Indications ................................................................................................................................3-98 Interpretation and Elimination of Non-Relevant Indications .......................................................................3-103 Methods of Recording MPI Indications .......................................................................................................3-103

SECTION VI PROCESS CONTROL OF MAGNETIC PARTICLE INSPECTION ............................................3-106 3.6 3.6.1 3.6.2 3.6.3 3.6.4 3.6.5 3.6.6 3.6.7 Magnetic Particle Process Control................................................................................................................3-106 Purpose and Scope ........................................................................................................................................3-106 General...........................................................................................................................................................3-106 Causes of System Degradation .....................................................................................................................3-106 Frequency of Process Control.......................................................................................................................3-107 Evaluating the Magnetic Particle Process ....................................................................................................3-107 Evaluating Equipment Effectiveness ............................................................................................................3-107 Evaluating Material Effectiveness ................................................................................................................3-113

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T.O. 33B-1-1 3.6.8 3.6.9 3.6.10 Additional Tests for Water Baths .................................................................................................................3-118 Disposition for Nonconformance Materials..................................................................................................3-119 Magnetic Particle Process Checklist.............................................................................................................3-119

SECTION VII MAGNETIC PARTICLE INSPECTION EQUATIONS ................................................................3-121 3.7 3.7.1 3.7.2 3.7.3 Magnetic Particle Equations..........................................................................................................................3-121 Rule-of-Thumb Formulas ..............................................................................................................................3-121 Cross-Sectional Area .....................................................................................................................................3-121 Calculating Coil Current ...............................................................................................................................3-122

SECTION VIII MAGNETIC PARTICLE INSPECTION SAFETY.......................................................................3-126 3.8 3.8.1 3.8.2 3.8.3 3.8.4 3.8.5 3.8.6 3.8.7 3.8.8 3.8.9 4 Magnetic Particle Safety ...............................................................................................................................3-126 Safety Requirements......................................................................................................................................3-126 General Precautions.......................................................................................................................................3-126 Floor Matting.................................................................................................................................................3-126 Wet Suspension Precautions .........................................................................................................................3-126 Arcing Precautions ........................................................................................................................................3-126 Head Stocks ...................................................................................................................................................3-126 UV-A (Black Light) Hazards........................................................................................................................3-126 Hazards of Aerosol Cans ..............................................................................................................................3-127 Magnetic Rubber Precautions .......................................................................................................................3-127

EDDY CURRENT INSPECTION METHOD................................................................................................................4-1 SECTION I EDDY CURRENT TESTING (ET) METHOD ......................................................................................4-1 4.1 4.1.1 4.1.2 4.1.3 4.1.4 4.1.5 4.1.6 4.1.7 4.1.8 4.1.9 General Capabilities of ET................................................................................................................................4-1 Introduction to ET .............................................................................................................................................4-1 Definition of Eddy Current ...............................................................................................................................4-2 Inspection With Eddy Current ..........................................................................................................................4-2 Limitations of Eddy Current Method ...............................................................................................................4-2 Variables Affecting Eddy Currents...................................................................................................................4-2 Eddy Current Techniques..................................................................................................................................4-3 Effect of Conductivity on Eddy Currents.........................................................................................................4-4 Crack Detection in Non-Ferromagnetic Materials ...........................................................................................4-9 Phase Lag at Depth .........................................................................................................................................4-11

SECTION II EDDY CURRENT PRINCIPLES AND THEORY .............................................................................4-13 4.2 4.2.1 Principles and Theory of ET...........................................................................................................................4-13 Materials and Processes ..................................................................................................................................4-13

SECTION III EDDY CURRENT EQUIPMENT TYPES .........................................................................................4-27 4.3 4.3.2 4.3.3 4.3.4 4.3.5 4.3.6 4.3.7 4.3.8 4.3.9 4.3.10 4.3.11 4.3.12 4.3.13 4.3.14 ET Equipment..................................................................................................................................................4-27 Components of an ET System ........................................................................................................................4-27 Eddy Current Subsystems ...............................................................................................................................4-28 Functions of the Eddy Current Instrument .....................................................................................................4-31 General Requirements .....................................................................................................................................4-31 Specific Instrumentation Requirements ..........................................................................................................4-31 Special Circuits and Processes........................................................................................................................4-33 Amplitude Detection........................................................................................................................................4-33 Multi-Frequency Eddy Current Systems ........................................................................................................4-33 Pulsed Eddy Current Techniques....................................................................................................................4-33 Metal Thickness Measurements ......................................................................................................................4-33 Presentations and Displays..............................................................................................................................4-33 Meters ..............................................................................................................................................................4-33 Cathode Ray Tube (CRT) Display .................................................................................................................4-33 v

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T.O. 33B-1-1 4.3.15 4.3.16 4.3.17 4.3.18 4.3.19 4.3.20 4.3.21 4.3.22 4.3.23 4.3.24 4.3.25 4.3.26 4.3.27 4.3.28 4.3.29 Digital Display.................................................................................................................................................4-33 Linear Time Base Display ..............................................................................................................................4-34 Recorders .........................................................................................................................................................4-34 Impedance Plane Eddy Current Test Equipment ...........................................................................................4-34 Digital Equipment............................................................................................................................................4-34 Mechanical Scanning.......................................................................................................................................4-34 Multi-Frequency Testing Techniques .............................................................................................................4-34 Dual Frequency Testing ..................................................................................................................................4-34 Pulsed Eddy Current Testing ..........................................................................................................................4-34 Low Frequency ET..........................................................................................................................................4-35 Barkhausen Noise Testing of Ferromagnetic Materials .................................................................................4-35 Alpha-Case on Titanium .................................................................................................................................4-35 Titanium Aluminide ........................................................................................................................................4-35 Magneto-Optic Imaging (MOI).......................................................................................................................4-35 Application of Advanced Techniques.............................................................................................................4-35

SECTION IV APPLICATION OF ET .......................................................................................................................4-36 4.4 4.4.1 4.4.2 4.4.3 4.4.4 4.4.5 4.4.6 4.4.7 4.4.8 4.4.9 4.4.10 4.4.11 4.4.12 4.4.13 4.4.14 4.4.15 4.4.16 4.4.17 4.4.18 4.4.19 4.4.20 4.4.21 4.4.22 4.4.23 4.4.24 4.4.25 4.4.26 4.4.27 4.4.28 4.4.29 4.4.30 4.4.31 4.4.32 4.4.33 4.4.34 4.4.35 4.4.36 4.4.37 4.4.38 4.4.39 4.4.40 4.4.41 vi General.............................................................................................................................................................4-36 Operating Point................................................................................................................................................4-36 Filters ...............................................................................................................................................................4-36 Modulation Analysis........................................................................................................................................4-37 Frequency Response ........................................................................................................................................4-38 Inspection of Fastener Holes...........................................................................................................................4-40 Fastener Hole Inspection Equipment ..............................................................................................................4-40 Lift-Off Compensation for Bolt-Hole Inspection...........................................................................................4-40 Sensitivity Settings ..........................................................................................................................................4-41 Scanning Speed................................................................................................................................................4-41 Bolt Hole Preparation......................................................................................................................................4-41 Probe to Edge Spacing ....................................................................................................................................4-41 Fixtures and Guides.........................................................................................................................................4-42 Fastener Holes Non-Removable Fasteners .....................................................................................................4-42 Probe Selection ................................................................................................................................................4-42 Standards for Nonremovable Fastener Holes .................................................................................................4-42 Fillets and Rounded Corner ............................................................................................................................4-42 Impedance Diagrams .......................................................................................................................................4-43 Corrosion..........................................................................................................................................................4-47 Frequency Selection ........................................................................................................................................4-48 Probe Selection ................................................................................................................................................4-48 Corrosion Reference Standards.......................................................................................................................4-48 Inspection Procedure-Corrosion Detection .....................................................................................................4-48 Part Preparation ...............................................................................................................................................4-48 Field Measurement of Conductivity ...............................................................................................................4-48 Conductivity of Aluminum Alloys .................................................................................................................4-48 Heat Treatment Effects on Aluminum Conductivity .....................................................................................4-49 Discrepancies in Aluminum Alloy Heat Treatment .......................................................................................4-49 Applications of Conductivity Measurement ...................................................................................................4-49 Conductivity Measurement..............................................................................................................................4-50 Equipment for Magnetic Materials .................................................................................................................4-50 Effects of Variations in Material Properties...................................................................................................4-50 Effects of Variations in Test Conditions ........................................................................................................4-51 Flaw Detection.................................................................................................................................................4-52 Inspection Material ..........................................................................................................................................4-52 Accessibility.....................................................................................................................................................4-52 Crack Detection ...............................................................................................................................................4-52 Probe Selection ................................................................................................................................................4-52 Lift-Off Effects ................................................................................................................................................4-56 Lift-Off Compensation Methods.....................................................................................................................4-56 Effects of Crack Location on Detectability....................................................................................................4-60 Effects of Scanning Techniques on Detection ...............................................................................................4-62

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T.O. 33B-1-1 4.4.42 4.4.43 4.4.44 Reference Standards for Cracks......................................................................................................................4-64 Thickness Measurement ..................................................................................................................................4-70 Measurement of Total Metal Thickness .........................................................................................................4-71

SECTION V INTERPRETING EDDY CURRENT SIGNALS ................................................................................4-76 4.5 4.5.1 4.5.2 4.5.3 4.5.4 4.5.5 4.5.6 4.5.7 ET Interpretation..............................................................................................................................................4-76 Flaw Detection.................................................................................................................................................4-76 Evaluation of Crack Indications......................................................................................................................4-76 Effect of Scan Rate and Pattern......................................................................................................................4-77 Openings, Large Holes, and Cutouts ..............................................................................................................4-78 Conductivity Measurement..............................................................................................................................4-78 Inspection Procedures......................................................................................................................................4-78 Calibration for Measuring Conductivity Values ............................................................................................4-79

SECTION VI EDDY CURRENT PROCESS CONTROL ........................................................................................4-80 4.6 4.6.1 4.6.2 4.6.3 ET Process Control..........................................................................................................................................4-80 General.............................................................................................................................................................4-80 Probe Test ........................................................................................................................................................4-80 Slot Test...........................................................................................................................................................4-80

SECTION VII EDDY CURRENT EQUATIONS .....................................................................................................4-81 4.7 4.7.1 4.7.2 4.7.3 4.7.5 4.7.6 4.7.7 4.7.8 4.7.10 4.7.11 Tables and Equations ......................................................................................................................................4-81 Resistance ........................................................................................................................................................4-88 Inductance ........................................................................................................................................................4-89 Fill Factor ........................................................................................................................................................4-90 Permeability .....................................................................................................................................................4-91 Depth of Penetration ()..................................................................................................................................4-92 Limit Frequency, f g. and the Similarity Law.............................................................................................4-93 Characteristic Frequency .................................................................................................................................4-93 Calculating Flaw Frequency for Setting Filters .............................................................................................4-93 Measurement of Conductivity.........................................................................................................................4-94

SECTION VIII EDDY CURRENT SAFETY............................................................................................................4-95 4.8 4.8.1 4.8.2 4.8.3 5 ET Safety .........................................................................................................................................................4-95 Safety Requirements........................................................................................................................................4-95 General Precautions.........................................................................................................................................4-95 ET.....................................................................................................................................................................4-95

ULTRASONIC INSPECTION METHOD .....................................................................................................................5-1 SECTION I GENERAL CAPABILITIES OF ULTRASONIC INSPECTION ..........................................................5-1 5.1 5.1.1 5.1.2 5.1.3 Introduction........................................................................................................................................................5-1 Introduction to Ultrasonic Inspection ...............................................................................................................5-1 Development of Ultrasonics..............................................................................................................................5-1 Ultrasonic Testing..............................................................................................................................................5-1

SECTION II PRINCIPLES AND THEORY OF ULTRASONIC INSPECTION......................................................5-2 5.2 5.2.1 5.2.2 5.2.3 5.2.4 5.2.5 5.2.6 Introduction........................................................................................................................................................5-2 Characteristics of Ultrasonic Energy ................................................................................................................5-2 Generation and Receiving of Ultrasonic Vibrations ........................................................................................5-2 Modes of Ultrasonic Vibration .........................................................................................................................5-3 Refraction and Mode Conversion .....................................................................................................................5-5 Ultrasonic Inspection Variables ........................................................................................................................5-7 Sound Beam Characteristics..............................................................................................................................5-8 vii

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T.O. 33B-1-1 SECTION III ULTRASONIC INSPECTION EQUIPMENT AND MATERIALS .................................................5-12 5.3 5.3.1 5.3.2 5.3.3 5.3.4 5.3.5 5.3.6 5.3.7 5.3.8 Introduction......................................................................................................................................................5-12 Ultrasonic Instruments.....................................................................................................................................5-12 Transducers ......................................................................................................................................................5-20 Specialized Transducers ..................................................................................................................................5-24 Wedges and Shoes...........................................................................................................................................5-25 Couplants .........................................................................................................................................................5-33 Inspection Standards........................................................................................................................................5-34 Bonded Structure Reference Standards ..........................................................................................................5-34 Thickness Measurement Equipment ...............................................................................................................5-36

SECTION IV ULTRASONIC INSPECTION APPLICATION ................................................................................5-38 5.4 5.4.1 5.4.2 5.4.3 5.4.4 5.4.5 5.4.6 5.4.7 5.4.8 5.4.9 5.4.10 5.4.11 5.4.12 Introduction......................................................................................................................................................5-38 Guidelines for Inspector Familiarization ........................................................................................................5-38 Basic Ultrasonic Inspection.............................................................................................................................5-38 Ultrasonic Reflections .....................................................................................................................................5-39 Data Presentation Methods..............................................................................................................................5-40 Relationship of a Scan Waveform Display to Distance.................................................................................5-42 Common Inspection Techniques.....................................................................................................................5-42 Ultrasonic Technique Development................................................................................................................5-47 Distance Amplitude Correction (DAC) Curve ...............................................................................................5-49 Attenuation Correction (Transfer)...................................................................................................................5-50 Inspection of Bonded Structures.....................................................................................................................5-56 Thickness Measurement ..................................................................................................................................5-56 Calibration and Thickness Measurement........................................................................................................5-57

SECTION V ULTRASONIC INSPECTION INTERPRETATION ..........................................................................5-59 5.5 5.5.1 5.5.2 5.5.3 5.5.4 5.5.5 5.5.6 5.5.7 5.5.8 5.5.9 Introduction......................................................................................................................................................5-59 Evaluation of Discontinuity Indications .........................................................................................................5-59 Types of Discontinuity Indications.................................................................................................................5-59 Test Part Variables ..........................................................................................................................................5-65 Discontinuity Variables ...................................................................................................................................5-68 Inspection Coverage of Bonded Structures ....................................................................................................5-68 Inspection Methods for Bonded Structures ....................................................................................................5-70 Techniques Associated With Instruments Dedicated to Bond Inspection.....................................................5-78 Thickness Measurement Test Part Preparation ..............................................................................................5-82 Thickness Measurement Considerations.........................................................................................................5-82

SECTION VI ULTRASONIC INSPECTION PROCESS CONTROLS...................................................................5-83 5.6 5.6.1 5.6.2 5.6.3 5.6.4 Introduction......................................................................................................................................................5-83 Ultrasonic Process Control Requirements ......................................................................................................5-83 Reference Standard Configuration ..................................................................................................................5-83 System (Equipment) Checks ...........................................................................................................................5-87 Transducer Verifications .................................................................................................................................5-96

SECTION VII ULTRASONIC INSPECTION EQUATIONS ................................................................................5-101 5.7 5.7.1 5.7.2 5.7.3 5.7.4 5.7.5 5.7.6 5.7.7 Introduction....................................................................................................................................................5-101 General...........................................................................................................................................................5-101 Snells Law ....................................................................................................................................................5-101 Determining the Angle of Incidence in Plastic to Generate 45-Degree Shear Wave in Aluminum .........5-101 Near Field ......................................................................................................................................................5-101 Beam Spread..................................................................................................................................................5-102 Calculating Acoustic Impedance...................................................................................................................5-102 Thickness Measurement Correlation Factor .................................................................................................5-105

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T.O. 33B-1-1 SECTION VIII ULTRASONIC INSPECTION SAFETY.......................................................................................5-107 5.8 5.8.1 5.8.2 5.8.3 6 Introduction....................................................................................................................................................5-107 Safety Requirements......................................................................................................................................5-107 General Precautions.......................................................................................................................................5-107 Ultrasonic Inspection.....................................................................................................................................5-107

RADIOGRAPHIC INSPECTION METHOD.................................................................................................................6-1 SECTION I RADIOGRAPHIC INSPECTION METHOD .........................................................................................6-1 6.1 6.1.1 6.1.2 6.1.3 6.1.4 6.1.5 6.1.6 6.1.7 6.1.8 6.1.9 General Capabilities of Radiographic Inspection .............................................................................................6-1 Introduction to Radiographic Inspection ..........................................................................................................6-1 History of X- and Gamma Radiation ...............................................................................................................6-2 Factors of Radiographic Inspection ..................................................................................................................6-3 The Physics of X-rays.......................................................................................................................................6-3 Properties of X- and Gamma Radiation ...........................................................................................................6-5 Differential Absorption of Radiation in Matter................................................................................................6-5 Exposure of Film to Radiation..........................................................................................................................6-7 When to use Radiography.................................................................................................................................6-8 Unique Properties of Gamma Radiation...........................................................................................................6-8

SECTION II PRINCIPLES AND THEORY OF RADIOGRAPHIC INSPECTION...............................................6-10 6.2 6.2.1 6.2.2 6.2.3 6.2.4 6.2.5 6.2.6 6.2.7 6.2.8 6.2.9 6.2.10 6.2.11 How X-rays Are Produced..............................................................................................................................6-10 Generating X-Radiation...................................................................................................................................6-10 Type of Radiation Produced by a Tube Head................................................................................................6-11 Effects of Voltage and Amperage on X-ray Production................................................................................6-12 X-ray Generators .............................................................................................................................................6-13 Intensity and Distribution of an X-ray Beam.................................................................................................6-15 Interaction of Radiation With Matter .............................................................................................................6-18 Radiation Energy .............................................................................................................................................6-22 Scatter Radiation..............................................................................................................................................6-23 Material Contrast .............................................................................................................................................6-24 Understanding Radiographic Film ..................................................................................................................6-24 Fundamentals of Digital Radiography ............................................................................................................6-29

SECTION III RADIOGRAPHIC EQUIPMENT .......................................................................................................6-33 6.3 6.3.1 6.3.2 6.3.3 6.3.4 6.3.5 6.3.6 6.3.7 6.3.8 6.3.9 6.3.10 6.3.11 6.3.12 6.3.13 Radiographic Inspection Equipment ...............................................................................................................6-33 Types of X-ray Generators..............................................................................................................................6-33 Types of X-ray Tubes .....................................................................................................................................6-33 Considerations in Choosing Equipment..........................................................................................................6-33 Considerations When Operating X-ray Equipment........................................................................................6-35 Standard Industrial X-ray Equipment in the DoD .........................................................................................6-36 Isotope Source Equipment ..............................................................................................................................6-37 Radiographic Film ...........................................................................................................................................6-39 Film Holders, Film Cassettes, and Radiographic Screens .............................................................................6-44 Quality Indicators ............................................................................................................................................6-47 Radiation Monitoring Devices and Instruments.............................................................................................6-50 Radiographic Processing Equipment ..............................................................................................................6-53 Film Evaluation Equipment ............................................................................................................................6-53 Digital Radiographic Viewing, Storage, Archival, and Printing Systems.....................................................6-54

SECTION IV APPLICATION OF RADIOGRAPHIC INSPECTION .....................................................................6-55 6.4 6.4.1 6.4.2 Effective Radiographic Inspections ................................................................................................................6-55 Introduction......................................................................................................................................................6-55 Factors Affecting Image Quality ....................................................................................................................6-55

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T.O. 33B-1-1 6.4.3 6.4.4 6.4.5 6.4.6 6.4.7 6.4.8 6.4.9 6.4.10 6.4.11 6.4.12 6.4.13 6.4.14 6.4.15 6.4.16 6.4.17 6.4.18 Radiographic Sensitivity..................................................................................................................................6-67 Improving Radiographic Sensitivity ...............................................................................................................6-71 Darkroom Design ............................................................................................................................................6-76 Radiographic Film ...........................................................................................................................................6-79 Film Handling Problems .................................................................................................................................6-80 Preparation for Manual Processing.................................................................................................................6-83 Storage of Radiographs ...................................................................................................................................6-83 Processing Chemicals ......................................................................................................................................6-84 Processing Radiographic Film ........................................................................................................................6-86 Manual Film Processing Procedure ................................................................................................................6-94 Automatic Film Processing .............................................................................................................................6-97 Silver Recovery .............................................................................................................................................6-100 Film Reproduction Technique.......................................................................................................................6-100 Film Artifacts.................................................................................................................................................6-101 Special Radiographic Techniques .................................................................................................................6-102 Digital Radiographic Techniques..................................................................................................................6-111

SECTION V INTERPRETATION OF RADIOGRAPHIC INSPECTION.............................................................6-112 6.5 6.5.1 6.5.2 6.5.3 6.5.4 6.5.5 6.5.6 6.5.7 6.5.8 6.5.9 6.5.10 6.5.11 6.5.12 6.5.13 6.5.14 6.5.15 6.5.16 6.5.17 6.5.18 6.5.19 6.5.20 Radiographic Interpretation...........................................................................................................................6-112 General...........................................................................................................................................................6-112 Radiographic Image Quality .........................................................................................................................6-112 Sensitivity ......................................................................................................................................................6-112 Definition or Detail .......................................................................................................................................6-112 Density ...........................................................................................................................................................6-114 Contrast ..........................................................................................................................................................6-115 Fog .................................................................................................................................................................6-115 Distortion and Magnification ........................................................................................................................6-116 Kilovoltage and Processing...........................................................................................................................6-116 Viewing Radiographs ....................................................................................................................................6-116 Reading (Interpreting) Radiographs..............................................................................................................6-118 Typical Use of Radiography .........................................................................................................................6-118 Castings..........................................................................................................................................................6-118 Casting Defects..............................................................................................................................................6-120 Welds .............................................................................................................................................................6-128 Welding Defects and Conditions ..................................................................................................................6-128 In-Service Inspections ...................................................................................................................................6-145 Assemblies .....................................................................................................................................................6-146 Radiographic Standards.................................................................................................................................6-146 Digital Radiographic Image Analysis...........................................................................................................6-146

SECTION VI PROCESS CONTROL OF RADIOGRAPHIC INSPECTION........................................................6-149 6.6 6.6.1 6.6.2 6.6.3 6.6.4 Radiographic Process Control.......................................................................................................................6-149 Scope and Purpose ........................................................................................................................................6-149 Radiographic Process Control Requirements ...............................................................................................6-149 Process Control in the Darkroom .................................................................................................................6-149 Controlling the Development Process ..........................................................................................................6-153

SECTION VII RADIOGRAPHIC INSPECTION EQUATIONS ...........................................................................6-155 6.7 6.7.1 6.7.2 6.7.3 6.7.4 6.7.5 6.7.6 6.7.7 6.7.8 Radiographic Equations.................................................................................................................................6-155 General...........................................................................................................................................................6-155 Inverse Square Law.......................................................................................................................................6-155 Source-to-Film Distance (SFD) ....................................................................................................................6-155 Film Density ..................................................................................................................................................6-156 Logarithms for Density and Exposure Calculations ....................................................................................6-156 Material Contrast Factor................................................................................................................................6-159 Image Unsharpness........................................................................................................................................6-159 Heel Effect.....................................................................................................................................................6-160

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T.O. 33B-1-1 SECTION VIII RADIOGRAPHIC INSPECTION SAFETY ..................................................................................6-161 6.8 6.8.1 6.8.2 6.8.3 6.8.4 6.8.5 6.8.6 6.8.7 6.8.8 6.8.9 Scope and Purpose of Radiation Protection .................................................................................................6-161 General...........................................................................................................................................................6-161 Responsibilities ..............................................................................................................................................6-161 (ALL) Qualifications of Civilian Industrial Radiographers .........................................................................6-166 (ALL) Industrial Radiographic Safety Training ...........................................................................................6-167 (ALL) Radiation Protection ..........................................................................................................................6-169 Industrial Radiographic Operations ..............................................................................................................6-180 Industrial Radiographic Installation Classifications .....................................................................................6-181 Mandatory Operating Procedures..................................................................................................................6-187 NDI Facility Design and Modification.........................................................................................................6-193

GLOSSARY.........................................................................................................................................................Glossary 1

LIST OF ILLUSTRATIONSNumber 1-1 2-1 2-2 2-3 2-4 2-5 2-6 2-7 2-8 2-9 2-10 2-11 2-12 2-13 2-14 2-15 2-16 2-17 2-18 2-19 2-20 2-21 2-22 2-23 2-24 2-25 2-26 2-27 2-28 2-29 2-30 Title Page

Typical Nondestructive Inspection Facility ...........................................................................................................1-16 The Penetrant Inspection Process.............................................................................................................................2-4 The Results of Inspection With a Medium Sensitivity Level Penetrant and a High Sensitivity Level Penetrant ...............................................................................................................................................................2-8 The Contact Angle, , is the Angle Between the Liquid and Solid Surface and is a Measure of the Wetting Ability...................................................................................................................................................2-12 The Rise and Depression of Liquid in a Capillary Tube is Dependant Upon the Contact Angle ......................2-13 Indications Produced by Penetrant of Four Different Sensitivity Levels Using Dry Developer.........................2-16 Diffusion of Emulsifier Into Penetrant During Lipophilic Emulsifier Dwell.......................................................2-18 Action of the Hydrophilic Remover Process .........................................................................................................2-20 The Effects of a Developer ....................................................................................................................................2-21 Cross-Section of a Typical High-Pressure Mercury Vapor Arc Bulb ..................................................................2-33 Transmission Curve for Kopp 41 Glass ................................................................................................................2-35 Flow Chart for Water Washable Penetrant Process (Method A)..........................................................................2-37 Flow Chart For Post-Emulsifiable Lipophilic Penetrant Process (Method B) .....................................................2-38 Flow Chart for Solvent Removable Penetrant Process (Method C) .....................................................................2-39 Flow Chart for Post-Emulsifiable Hydrophilic Penetrant Process (Method D) ...................................................2-40 Graph Showing the Approximate Drying Times for Two Types of Nonaqueous Developers at Various Temperatures ......................................................................................................................................................2-46 Graph Showing the Viscosities of Several QPL Penetrants at Various Temperatures ........................................2-49 Graph Showing the Comparison of Dwell Time Vs. Viscosity for Two Types of Penetrants ...........................2-50 Comparison of Adequate Dwell Vs. Insufficient Dwell on a Thermally Cracked Aluminum Block.................2-52 Cracked-Chrome Panels Showing Effects of Insufficient Wash, Optimum Wash, and Excessive Wash...........2-55 Effects of Optimum, Insufficient, and Excessive Hydrophilic Removal Dwell Time.........................................2-58 Effects of Optimum, Insufficient, and Excessive Remover Dwell Time .............................................................2-60 Effects of Proper vs. Excessive Drying .................................................................................................................2-66 Cracked, Aluminum Panel Comparing Results of an Optimum Thickness Layer of Developer (Top) to an Excessive Thickness Layer of Developer (Bottom) ....................................................................................2-72 Comparison of Four Cracked Chrome Test Panels With Different Sensitivity Levels .......................................2-75 Electromagnetic Spectrum Shows the Relatively Narrow Band of Black Light .................................................2-79 Relative Response of a Typical Human Eye to Visible Light at Two Different Light Levels, (A) 100 Lumens, and (B) 2.0 Lumens............................................................................................................................2-80 Typical Penetrant Indications (a, b, c, d)...............................................................................................................2-85 Micrograph of a Cross-Section Through a Fatigue Crack Showing the Transgranular Progression of the Crack...................................................................................................................................................................2-87 Micrograph of a Cross-Section Through a Stress-Corrosion Crack .....................................................................2-88 Location of Camera and Lights for Photographing Fluorescent Indications........................................................2-90

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T.O. 33B-1-1 2-31 2-32 2-33 2-34 2-35 3-1 3-2 3-3 3-4 3-5 3-6 3-7 3-8 3-9 3-10 3-11 3-12 3-13 3-14 3-15 3-16 3-17 3-18 3-19 3-20 3-21 3-22 3-23 3-24 3-25 3-26 3-27 3-28 3-29 3-30 3-31 3-32 3-33 3-34 3-35 3-36 3-37 3-38 3-39 3-40 3-41 3-42 3-43 3-44 3-45 3-46 3-47 3-48 3-49 3-50 3-51 3-52 xii Processed Starburst Panel With Indications ..........................................................................................................2-94 Magnified View of Largest Manufactured Indication ...........................................................................................2-95 Illustration of Crack Depth in Cracked-Chrome Panel .......................................................................................2-104 Specific Gravity Hydrometer Readings for Two Water-Suspended Developers ...............................................2-114 Specific Gravity Hydrometer Readings Versus Concentration for One Manufacturers Water-Soluble Developers........................................................................................................................................................2-116 Horseshoe Magnet ....................................................................................................................................................3-3 Horseshoe Magnet With Poles Close Together ..................................