ASNT

NONDESTRUCTIVE TESTING HANDBOOK FOURTH EDITION

RADIOGRAPHIC TESTING RICHARD H. BOSSI AND TREY GORDON, TECHNICAL EDITORS VOLUME 3

Copyright © 2019 by The American Society for Nondestructive Testing.

The American Society for Nondestructive Testing Inc. (ASNT) is not responsible for the authenticity or accuracy of information herein. Published opinions and statements do not necessarily reflect the opinion of ASNT. Products or services that are advertised or mentioned do not carry the endorsement or recommendation of ASNT. No part of this publication may be reproduced or transmitted in any form, by means electronic or mechanical including photocopying, recording or otherwise, without the expressed prior written permission of The American Society for Nondestructive Testing Inc. IRRSP, NDT Handbook, The NDT Technician , and asnt.org are trademarks of The American Society for Nondestructive Testing Inc. ACCP, ASNT, Level III Study Guide, Materials Evaluation, Nondestructive Testing Handbook, Research in Nondestructive Evaluation , and RNDE are registered trademarks of The American Society for Nondestructive Testing Inc.

First printing 12/19 ebook 12/19

ISBN: 978-1-57117-432-1 (print) ISBN: 978-1-57117-433-8 (ebook)

Printed in the United States of America

Published by: The American Society for Nondestructive Testing Inc. 1711 Arlingate Lane Columbus, OH 43228-0518 asnt.org

Publications Team:

Toni Kervina, Interim Director of Publications

Editorial: Karen F. Balkin, Handbook Editor

Production: Joy Grimm, Production Manager Synthia Jester, Graphic Designer and Illustrator

ASNT Mission Statement: ASNT exists to create a safer world by advancing scientific, engineering, and technical knowledge in the field of nondestructive testing.

ASNT Code of Ethics : The ASNT Code of Ethics was developed to provide members of the Society with broad ethical statements to guide their professional lives. In spirit and in word, each ASNT member is responsible for knowing and adhering to the values and standards set forth in the Society’s Code. More information, as well as the complete version of the Code of Ethics , can be found on ASNT’s website, asnt.org.

FOREWORD

AIMS OF NDT HANDBOOK The publication of another volume of the NDT Handbook is a good occasion to ref lect on the goals of the ASNT Handbook series. Handbooks exist in many disciplines of science and technology, and certain features set them apart from other reference works. A handbook should ideally give the basic knowledge necessary for an understanding of the technology, including both scientific principles and means of application. Handbooks are reference documents, rarely read cover to cover but consulted for specific information. The NDT Handbook is written for a broad audience but includes technical details up through college physics. Assumptions about the reader vary according to the subject in any given chapter. It is not possible or practical for the handbook to provide all the background ancillary to nondestructive testing. A handbook offers a view of its subject at a certain period in time. Even before it is published, it starts to get obsolete. The authors and editors do their best to be current but the technology will continue to change even as the book goes to press. Moreover, the NDT Handbook ref lects, to the best of our ability, technology that is being used by industry. Standards, specifications, recommended practices, and inspection procedures may be discussed in a handbook for instructional purposes, but at a level of generalization that is illustrative rather than comprehensive. Standards writing bodies take great pains to ensure that their documents are definitive in wording and technical accuracy. People writing contracts or procedures should consult real standards when appropriate. Those who design qualifying examinations or study for them draw on the NDT Handbook as a quick and convenient way of approximating the body of knowledge. Committees and individuals who write or anticipate questions are selective in what they draw from any source. The parts of the NDT Handbook that give scientific background, for instance, may have little bearing on a practical examination. Other parts of a handbook are specific to a certain industry. The NDT Handbook cannot include everything on its subject matter but does try to cover as much as practical.

Volunteer activity including peer review draws on the expertise in ASNT’s Technical and Education Council and is coordinated through the Handbook Development Committee.

Richard H. Bossi ASNT Handbook Development Committee Chair

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ADDITIONAL INFORMATION In ASNT publications, the words discontinuity and defect have specific meanings. These words are used as follows: l A discontinuity is an intentional (such as drilled holes) or unintentional interruption in the physical structure or configuration of a material or component. NDT techniques reveal indications of discontinuities. Discontinuities may exist without being detected. l A defect is a discontinuity whose size, shape, orientation, or location make it detrimental to the useful service of the object, or exceed accept/reject criteria of an applicable specification. Some discontinuities do not exceed an accept/reject criterion and are therefore not defects. l The process for determining rejectability is interpretation or evaluation . All defects are discontinuities, but not all discontinuities are defects. In 2018 ASNT accepted the ASTM E1316 definitions of calibration and standardization for use in its publications. These words are used as follows: l Calibration is the comparison (which may include adjustment) of a test instrument to a known reference that is normally traceable to some recognized authority (e.g., NIST). Calibration is typically performed by an organization considered qualified to do so (e.g., an accredited laboratory, or in some cases, the instrument manufacturer) at a determined, periodic interval. Calibration of electronic instrumentation typically involves verification of the linearity of the instrument’s response over its usable range. l S tandardization is typically completed prior to performing an NDT test, and may also be performed at times during the performance of the test and at the completion of the test as a validation of proper instrument operation. It is the adjustment of an NDT instrument using a reference standard (that contains a known condition) to obtain or establish a known and reproducible response.

FOREWORD

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PREFACE

RADIOGRAPHIC TESTING METHOD Radiographic testing has been a preeminent method of nondestructive testing since the discovery of X-rays in 1895. Film radiography in particular has been the backbone of industrial applications of penetrating radiation. It is fundamentally a very elegant analog process that provides an internal evaluation of solid objects. Although film radiography remains a widely used method of radiographic testing, many other penetrating radiation techniques for nondestructive testing have been developed and implemented. The advancements in speed and capability of digital data processing since the writing of the third edition of the radiographic testing volume have dramatically increased the application of digital methods for penetrating radiation inspections. The transition from analog to digital technology will continue into the future. This fourth edition volume of the Nondestructive Testing Handbook builds on material in the first (1959), second (1985) and third (2002) editions. The many contributors to this volume have assembled the basic body of knowledge for radiographic testing. Fundamental information in the earlier editions of the radiography volume has been maintained and enhanced, while dated or rarely used material has been dropped. The earlier editions thus remain useful references — not only for historical purposes but for material that could no longer be included in the present edition. Considerable updated information, particularly in the area of digital imaging, data processing, and digital image reconstruction, has been added in this fourth edition. Other material has been updated with recent information in such areas as radiation sources, standards, and applications. The team of contributors has tried to prepare as useful a text as possible. In many cases, items are discussed in multiple chapters to keep the continuity of the discussion in that particular chapter. This also provides multiple contexts for understanding concepts and techniques. In other cases, the handbook may rely on other chapters for details on a particular concept. The reader is encouraged to refer to the index to find information on items of interest in multiple chapters. Because of the current rate of change in technology, it is not possible to have a handbook that is completely up to date. This handbook contains the fundamental, as well as the most recent, material available at the time of its writing. Where possible, tables and figures are used to serve as a quick and ready means of finding essential technical information. The references for each chapter should be helpful for the reader seeking additional material. Readers are also encouraged to use the internet and ASNT’s website to find supplemental material on equipment and topics that are subject to change with technological advancement. It has been the pleasure of the technical editors to work with the authors and ASNT’s Nondestructive Testing Handbook staff to provide this fourth edition of the radiography handbook. We wish to thank the all the contributors, including those named in the current volume, those who provided material to the contributors and may not have been named, and those whose contributions to earlier editions have been carried over to this edition. We hope this edition proves useful as both a quick reference for technical details and a source of fundamental information for comprehensive understanding.

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ACKNOWLEDGMENTS This Radiographic Testing Volume 3 of the fourth edition of the ASNT Nondestructive Testing Handbook is indebted to preceding editions. Additionally, and very importantly much of the text has been revised, reedited, and updated by many new authors and reviewers so that the book ref lects both current techniques, equipment, and technology as well as historical examples and fundamentals. The Technical Editors are indebted to the handbook contributors, authors and reviewers, who volunteered to help assemble this book. The ASNT Penetrating Radiation Committee also played a key role in the setting the direction for updates and additions that have been incorporated. A special thanks to Karen Balkin, ASNT Handbook Editor, for her diligent efforts to gather, assemble, and edit the information into an attractive and functional format. We also acknowledge the service of Patrick O. Moore (1951-2017) to ASNT for his decades- long contribution as editor of the Nondestructive Testing Handbook series, creating volumes that provide clear, accurate text and illustrative figures that are the hallmark of a quality reference.

Richard H. Bossi Trey Gordon Technical Editors

WORKING GROUP Contributors Vijay Alreja, VJ Technologies Inc. Luke K. Banks, Digicon Harold Berger, Rockville, Maryland Hassina Bilheux, Oak Ridge National Laboratory Richard Bossi, Renton, Washington Karen L. Bruer, Amee Bay LLC Clifford Bueno, GE Global Research Center Chen Dai, VJ Technologies Inc. John P. Ellegood, Radiographic Solutions LLC Gary E. Georgeson, Lawrence Livermore National Laboratory Trey Gordon, Renton, Washington Kenneth Herwig, Oak Ridge National Laboratory Boeing Company Steven M. Glenn,

Enrico Quintana, Sandia National Laboratories Mansoureh Norouzi Rad, Carl Zeiss Microscopy LLC Edward H. Ruescher, Coueur d’Alene, Idaho Morteza Safai, Boeing Company Lou Santodonato, Oak Ridge National Laboratory Daniel J. Schneberk, Lawrence Livermore National Laboratory Mark Shilton, QSA Global Inc. Bryan Shumway, Jr., Prime NDT Services George R. Strabel, Norton Shores, Michigan Michael J. Taylor, Phoenix LLC Kyle R. Thompson, Sandia National Laboratories Marvin Trimm, Savannah River Laboratory Jeffery A. Umbach, Palm Beach Gardens, Florida Karen Ursel, Carestream Health Inc.

Thomas S. Jones, Winchester, Virginia Burke L. Kernen, Sandia National Laboratories Timothy Kinsella, Dassault Falcon Jet Corp. Stuart A. Kleven, Alloyweld Inspection Company Inc. Mark Lessard, Thermo Fisher Scientific Xin Li, GE Global Research Center Richard D. Lopez, John Deere Moline Technology Innovation Center Thomas Maeder, Boeing Company Steven A. Mango, Morganton, Georgia Harry E. Martz Jr., Lawrence Livermore National Laboratory

Jim Neal, Fuji Film W.L. Nighan,

ETM-Electromatic Inc. J. Scott Price, GE Global Research Center

PREFACE

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Trey Gordon, Renton, Washington David P. Harvey, Los Alamos National Laboratory Dietmar F. Henning, Winston-Salem, North Carolina Timothy E. Jones, American Society for Nondestructive Testing Doron Kishoni, Business Solutions USA Richard D. Lopez, John Deere Moline Technology Innovation Center Xavier P.V. Maldague, Université Laval, Quebec George A. Matzkanin, Erie, Colorado Michael V. McGloin, Loveland, Ohio Scott D. Miller, Dripping Springs, Texas David G. Moore, Sandia National Laboratories Yi Cheng (Peter) Pan, Therm-O-Disc Robert F. Plumstead, Municipal Testing Laboratory Mark R. Pompe, West Penn Testing Group—Mistras Todd E. Sellmer, Nuclear Waste Partnerships Vijay Srinivasan, Automotive and Industrial Equipment Roderic K. Stanley, NDE Information Consultants Kenneth Starry, IVC Technologies Satish S. Udpa, Michigan State University Mark F.A. Warchol, Texas Research Institute Glenn A. Washer, University of Missouri, Columbia NDT Enterprises Ronnie K. Miller,

Gregory A. Mohr, Navel Nuclear Laborotory Ramon S. Fernandez Orozco, Fercon Research SC Emery Roberts, Mistras Group Inc. Matt Roberts, Virtual Media Integration Stanislav I. Rokhlin, Ohio State University Frank J. Sattler, Sattler Consultants Company Inc. Kyle D. Stoll, NSWC Crane Michael L. Turnbow, Consulting and Inspection Services Vijay Srinivasan, Con Edison, Bronx, New York Howard Wallace, Boeing Company William P. Winfree, NASA Langley Research Center Handbook Development Committee Karen Balkin, American Society for Nondestructive Testing Richard H. Bossi, Renton, Washington Lisa Brasche, Pratt and Whitney James R. Cahill, General Electric Sensing and Inspection Technologies Robert E. Cameron, Conroe, Texas John Steve Cargill, Aerospace Structural Integrity Josh deMonbrun, SubSea NDT Nat Y. Faransso, KBR Ramon S. Fernandez Orozco, Fercon Research SC Jerry D. Fulin, Fugro Consultants

Reviewers Anthony S. Balowski, Alyeska Pipeline Service Comp. John Barton, San Diego, California Klaus Bavendiek, Yxlon John Chen, Schlumberger Aaron E. Craft, Idaho National Laboratory David Crocker, QSA Global Inc. David Culbertson, NDT Technical Services Inc. Robert P. Devries, NDT Solutions Robert A. Feole, Feole Technologies Inc. Toshihide Fukui, Kobe Steel Ltd. Edward Jimenez, Sandia National Laboratories Darrell W. Harris, Pacific Gas and Electric David P. Harvey, Los Alamos National Laboratory George K. Hodges, Hodges NDT LLC James F. Hunter, Los Alamos National Laboratory Erik Iverson, Oak Ridge National Laboratory

Danny L. Keck, Magnolia, Texas

Bradley S. Kienlen, Zachary, Louisiana Claudia V. Kropas-Hughes,

West Carrollton, Ohio Kenneth J. LaCivita, US Air Force Kevin L. McClain, Hellier Scott McClain, US Army Michael V. McGloin, NDT Enterprises LLC

PREFACE

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DEDICATION

DR. RICHARD H. BOSSI

This fourth edition of the ASNT NDT Radiographic Testing Handbook is dedicated to ASNT Fellow and my co-technical editor Dr. Richard H. Bossi. Three years ago, when he asked me to join him in working on this handbook, I was honored and accepted without hesitation. The opportunity to work with Dick on any NDT project, especially one of this depth and scope, was a career highlight and unique learning experience. During this time, I have not only learned from Dick about X-ray and neutron technology, but also how to work effectively with the many contributors, reviewers, and ASNT staff members who have aided in the completion of this handbook. Dick’s experience as a handbook technical editor and contributor spans almost two decades—he worked on the third edition of the Nondestructive Testing Handbook: Radiographic Testing and the ASNT Industry Handbook: Aerospace NDT . He has also served for many years as the associate technical editor and a technical editor for the ASNT journal, Materials Evaluation, and he has served as the chair of the ASNT Handbook Development Committee. Those of us who have been mentored by Dick are determined to carry forward his vision and dedication to support ASNT and the global NDT community. I feel very lucky to have worked with Dick on this handbook. I consider him not only a valued technical colleague and mentor but also a great friend. Thank you, Dick.

Trey Gordon Handbook Co-technical Editor December 2019

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CONTENTS

FOREWORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . III PREFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V DEDICATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VIII CHAPTER 1 INTRODUCTION TO RADIOGRAPHIC TESTING. . . . . . . . . . . 1 Part 1. Nondestructive Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Part 2. History of Radiographic Testing. . . . . . . . . . . . . . . . . . . . . . . . 16 Part 3. Management of Radiographic Testing . . . . . . . . . . . . . . . . . . . . . . 24 Part 4. Units of Measure for Radiographic Testing. . . . . . . . . . . . . . . . . . . . 32 CHAPTER 2 PENETRATING RADIATION PHYSICS. . . . . . . . . . . . . . . 37 Part 1. Atomic Structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Part 2. Electromagnetic Radiation Characteristics. . . . . . . . . . . . . . . . . . . . 41 Part 3. Radioactive Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Part 4. Introduction to the Neutron. . . . . . . . . . . . . . . . . . . . . . . . . . 50 CHAPTER 3 RADIATION SOURCES AND EXPOSURE DEVICES. . . . . . . . . 51 Part 1. X-ray Tubes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Part 2. Accelerator Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 Part 3. Radioisotope Sources and Exposure Devices . . . . . . . . . . . . . . . . . . . 66 Part 4. Neutron Sources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

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CHAPTER 4 RADIATION SAFETY AND PERSONNEL PROTECTION. . . . . . . 97 Part 1. Dose Definitions and Exposure Levels. . . . . . . . . . . . . . . . . . . . . . 99 Part 2. Radiation Measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . 102 Part 3. Radiation Protection and Measurements. . . . . . . . . . . . . . . . . . . . 103 Part 4. Basic Exposure Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 Part 5. Shielding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 Part 6. Management of Radiation Safety . . . . . . . . . . . . . . . . . . . . . . . 122 Part 7. Neutron Radiographic Safety. . . . . . . . . . . . . . . . . . . . . . . . . 129 CHAPTER 5 PRINCIPLES OF RADIOGRAPHY. . . . . . . . . . . . . . . . . 131 Part 1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 Part 2. Radiographic Geometry. . . . . . . . . . . . . . . . . . . . . . . . . . . 135 Part 3. Radiographic Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 Part 4. Energy Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 Part 5. Scatter Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154 Part 6. Image Quality Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 Part 7. Probability of Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . 161 CHAPTER 6 PRINCIPLES OF DIGITAL IMAGING. . . . . . . . . . . . . . . . 163 Part 1. Digital Image Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 Part 2. Image Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170 Part 3. Human Perception and Image Display. . . . . . . . . . . . . . . . . . . . . 176 Part 4. Image Enhancement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185 CHAPTER 7 FILM RADIOGRAPHY FOR INDUSTRY. . . . . . . . . . . . . . 199 Part 1. Industrial X-ray Films. . . . . . . . . . . . . . . . . . . . . . . . . . . . 201 Part 2. Film Image Formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218 Part 3. Film Handling and Equipment. . . . . . . . . . . . . . . . . . . . . . . . 229 Part 4. Film Viewing Equipment. . . . . . . . . . . . . . . . . . . . . . . . . . . 237 Part 5. Film Digitization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250 Part 6. Silver Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253

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CHAPTER 8 COMPUTED RADIOGRAPHY FOR NONDESTRUCTIVE TESTING. . . . . . . . . . . . . . . . . . . . . . 257 Part 1. Principles of Computed Radiography. . . . . . . . . . . . . . . . . . . . . . 259 Part 2. Computed Radiography Practices. . . . . . . . . . . . . . . . . . . . . . . 264 Part 3. Computed Radiography System Testing. . . . . . . . . . . . . . . . . . . . . 272 CHAPTER 9 DIGITAL RADIOGRAPHY WITH DETECTOR ARRAYS . . . . . . . 277 Part 1. Overview of Digital Radiography . . . . . . . . . . . . . . . . . . . . . . . 279 Part 2. Digital Detector Array Technologies. . . . . . . . . . . . . . . . . . . . . . 281 Part 3. Digital Detector Array Properties. . . . . . . . . . . . . . . . . . . . . . . 289 Part 4. Digital Detector Array Practices . . . . . . . . . . . . . . . . . . . . . . . . 299 CHAPTER 10 RADIOSCOPY OF OBJECTS AND ASSEMBLIES. . . . . . . . . 307 Part 1. Principles of Radioscopy. . . . . . . . . . . . . . . . . . . . . . . . . . . 309 Part 2. Radioscopic Imaging Systems . . . . . . . . . . . . . . . . . . . . . . . . . 317 Part 3. Radioscopy Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 328 Part 4. Radioscopic Practices . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332 CHAPTER 11 COMPUTED TOMOGRAPHY FOR NONDESTRUCTIVE TESTING. . . . . . . . . . . . . . . . . . . . . . 337 Part 1. Introduction and Practice of Industrial Computed Tomography. . . . . . . . . . 339 Part 2. Principles of Computed Tomography. . . . . . . . . . . . . . . . . . . . . . 344 Part 3. Resolution and Contrast . . . . . . . . . . . . . . . . . . . . . . . . . . . 350 Part 4. Computed Tomographic Systems. . . . . . . . . . . . . . . . . . . . . . . . 352 Part 5. Image Quality Measurement and Reference Standards . . . . . . . . . . . . . . 358 Part 6. Partial Scanning Techniques. . . . . . . . . . . . . . . . . . . . . . . . . 375 Part 7. Computed Tomography Examples . . . . . . . . . . . . . . . . . . . . . . . 382 Part 8. Advanced Analysis Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . 386

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CHAPTER 12 NEUTRON RADIOGRAPHY FOR NONDESTRUCTIVE TESTING. . . . . . . . . . . . . . . . . . . . . . 389 Part 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391 Part 2. Principles of Neutron Radiography . . . . . . . . . . . . . . . . . . . . . . 393 Part 3. Standards and Image Quality . . . . . . . . . . . . . . . . . . . . . . . . . 407 Part 4. Applications of Neutron Radiography . . . . . . . . . . . . . . . . . . . . . 411 Part 5. Advanced Techniques of Neutron Radiography. . . . . . . . . . . . . . . . . 418 CHAPTER 13 SPECIAL RADIOGRAPHIC TECHNIQUES. . . . . . . . . . . . 425 Part 1. X-ray Backscatter Imaging. . . . . . . . . . . . . . . . . . . . . . . . . . 427 Part 2. X-ray Microscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 441 Part 3. Stereo Radiography and Parallax . . . . . . . . . . . . . . . . . . . . . . . 445 Part 4. Dual-Energy X-ray Radiography and Computed Tomography . . . . . . . . . . . 454 Part 5. Flash Radiography. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 466 Part 6. X-ray Diffraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 473 Part 7. X-ray Fluorescence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 476 CHAPTER 14 RADIOGRAPHIC TESTING OF METAL CASTINGS. . . . . . . . 481 Part 1. Introduction to Radiographic Testing of Metal Castings. . . . . . . . . . . . . . 483 Part 2. General Radiographic Techniques for Metal Castings. . . . . . . . . . . . . . . 485 Part 3. Radiographic Indications for Metal Castings . . . . . . . . . . . . . . . . . . 493 Part 4. Radiographic Testing and Process Scheduling. . . . . . . . . . . . . . . . . . 497 Part 5. Problems in Radiographic Testing of Metal Castings. . . . . . . . . . . . . . . 499 CHAPTER 15 RADIOGRAPHIC TESTING OF WELDS. . . . . . . . . . . . . . 503 Part 1. Introduction to Radiographic Testing of Welds . . . . . . . . . . . . . . . . . 505 Part 2. Weld Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 506 Part 3. Discontinuities in Welds. . . . . . . . . . . . . . . . . . . . . . . . . . . 510 Part 4. Technique Development. . . . . . . . . . . . . . . . . . . . . . . . . . . 515 Part 5. Standards and Specifications for Radiographic Testing of Welds . . . . . . . . . . 524 Part 6. Radiography of Weld Discontinuities. . . . . . . . . . . . . . . . . . . . . . 526

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CHAPTER 16 OTHER APPLICATIONS OF RADIOGRAPHIC TESTING: HISTORICAL REVIEW. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 539 Part 1. Pipe and Tubing Applications . . . . . . . . . . . . . . . . . . . . . . . . . 541 Part 2. Pressure Vessel and Tank Applications . . . . . . . . . . . . . . . . . . . . . 553 Part 3. Nuclear Reactor Applications. . . . . . . . . . . . . . . . . . . . . . . . . 555 Part 4. Radiation Gauging of Density or Thickness. . . . . . . . . . . . . . . . . . . 566 Part 5. Radiographic Testing in the Aerospace Industry. . . . . . . . . . . . . . . . . 576 Part 6. Radiographic Testing of Electronic Components . . . . . . . . . . . . . . . . . 599 Part 7. Radiographic Testing in Art and Historic Conservation. . . . . . . . . . . . . . 605 Part 8. Infrastructure Applications of Radiographic Testing. . . . . . . . . . . . . . . 615 Part 9. Radiographic Testing of Consumer Goods. . . . . . . . . . . . . . . . . . . . 620 Part 10. Radiographic Testing for Airport Security . . . . . . . . . . . . . . . . . . . 625 CHAPTER 17 ATTENUATION COEFFICIENTS FOR RADIOGRAPHIC TESTING. . . . . . . . . . . . . . . . . . . . . . . . 629 Part 1. Introduction to Attenuation Coefficients. . . . . . . . . . . . . . . . . . . . 631 Part 2. Attenuation Coefficient Tables. . . . . . . . . . . . . . . . . . . . . . . . . 633 GLOSSARY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 677 REFERENCES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 707 INDEX. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 729 FIGURE SOURCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 753

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CHAPTER 1

INTRODUCTION to Radiographic Testing

CONTENTS

PART 1 Nondestructive Testing, 3 PART 2 History of Radiographic Testing, 16

PART 3 Management of Radiographic Testing, 24 PART 4 Units of Measure for Radiographic Testing, 32

CONTRIBUTORS

Richard H Bossi (Parts 1 and 4) Renton, Washington

Marvin W Trimm (Part 3) Savannah River Laboratory Aiken, South Carolina

Harry Berger (Part 2) Digitome Rockville, Maryland

CHAPTER 1

2

Part 1

Nondestructive Testing PART 1

Nondestructive testing (NDT) comprises those test methods used to examine or inspect a part, material, structure, or system without impairing its future usefulness (ASNT 1996). The term is applied to nonmedical investigations of material integrity. Nondestructive testing asks: “Is this material fit for service?” Various performance and proof tests, in contrast, ask: “Does this component work?” For example, circuit checking by running electric current or hydrostatic pressure proof testing is not considered NDT. Some material investigations involve taking a sample of the inspected part for testing that is inherently destructive. A noncrit- ical portion of a product may be removed and destructively tested mechanically or analytically. For example, a pressure vessel may be scraped or shaved to get a sample for electron microscopy. Although future usefulness of the vessel is not impaired by the loss of material, the procedure is inherently destructive and the shaving itself has been removed from service permanently. NDT methods are important tools employed in quality assurance and quality control procedures. NDT is not confined to discontinuity detection such as cracks, porosity, inclusions, or disbonds. Other issues include dimension measurements, such as wall thinning from corrosion, wear or environ- ment, leak detection, and strain measurements. Nondestructive material characterization is an important field concerned with material properties, including material identification and microstruc- tural characteristics that have a direct inf luence on the service life of the test object.

Nondestructive testing has also been defined by listing or classifying the various methods (ASNT 1996; Wenk 1987; DOD TM 55-1500-335-23). This approach is practical in that it typically highlights methods in use by industry. PURPOSES OF NONDESTRUCTIVE TESTING Since the 1920s, the art of testing without destroy- ing the test object has developed from a laboratory curiosity to an indispensable tool of production and in-service inspection. No longer is visual examination of materials, parts, and complete products the principal means of determining adequate quality. Nondestructive tests in great variety are in worldwide use to detect variations in structure, minute changes in surface finish, the presence of cracks or other physical discontinuities, to measure the thickness of materials and coating, and to determine other characteristics of industrial products. The various nondestructive testing methods are covered in detail in the literature, but it is always wise to consider objectives before selecting a method. What is the use of nondestructive testing? Why do thousands of industrial concerns buy the testing equipment, pay the subsequent operating costs of the testing, and even reshape manufac- turing processes to fit the needs and findings of nondestructive testing? Modern nondestructive tests are used (1) to ensure product integrity and, in turn, reliability;

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(2) to avoid failures, prevent accidents, and save human life (Figures 1 and 2); (3) to make a profit for the user; (4) to ensure customer satisfaction and maintain the manufacturer’s reputation; (5) to aid in better product design; (6) to control manufac- turing processes; (7) to lower manufacturing costs; (8) to maintain uniform quality levels; and (9) to ensure operational readiness. These reasons for widespread profitable use of nondestructive testing are sufficient in themselves, but parallel developments have contributed to its growth and acceptance. Increased Engineering Demand In the interest of greater performance and reduced cost, the design engineer seeks to reduce weight. Designing with lightweight metal alloys (aluminum or magnesium alloys for steel or iron); polymer composites, or ceramics are examples. Such lighter weight components are not necessarily of the same size or design as those they replace. These changes may subject parts to increased stress levels. The stress to be supported is seldom static. It often f luctuates and reverses at low or high frequencies. Frequency of stress reversals increases with the speeds of operation, risking fatigue damage. Because nondestructive testing can reveal, characterize, and quantify anomalies on the surface and throughout the component’s volume, it is a major tool to ensure raw materials and fabricated components meet design expectation for quality,

reliability, and service. Nondestructive testing can provide data to let engineers reduce safety factors and cost. Due to the success of nondestructive testing in fabrication, operation engineers use nondestructive testing to locate and describe service discontinuities and monitor their growth. Today’s nondestructive testing technologies ensure structural integrity of operating components that allow continued service of critical components. Extended component life reduces operational costs while ensuring continued safe operation. For this and other reasons, national codes and standards have also adopted nondestruc- tive testing in in-service requirements. The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, for example, has an entire section dedicated to in-service inspection of critical components. That section uses nondestructive testing as its primary tool. ASME Section V ( Nondestructive Examination ) provides the “how to” requirements for the performance of various nondestructive testing methods. Other sections of the Boiler and Pressure Vessel Code also identify specific requirements when nondestructive test methods are to be used. Engineers also use nondestructive testing for plant life extension. Most designs project an expected life of operation. For example, nuclear reactors at energy generation stations in the United States were designed originally for a service life of 40 years. After their designed service life, the reactor would be shut down and decommissioned. However, because of the critical need for energy, the lead time for the construction of new power plants, and the cost of construction, plant owners have commissioned studies, including nondestructive testing, to determine if plant operations can safely continue beyond 40 years. Once complete, the plant owner will submit a formal request to the appropri- ate regulatory authority (in this example, the US Nuclear Regulatory Commission) using the study as a basis for continued service. As technology improves and as service requirements increase, structures and equipment are subjected to greater variations and to wider extremes of all kinds of stress, creating a demand

Figure 1 View of Aloha Airlines Flight 243 pressure cabin skin departure looking aft on left-hand side of fuselage (FAA training), 1988.

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(a)

(b)

(c)

Figure 2 Aftermath of material failures: (a) defective welds in gas pipelines led to explosion and destruction in San Bruno, California, 2010; (b) boiler explosion; (c) problems in pipe seam welds, including hook cracks, led to major oil spill in Mayflower, Arkansas, 2013; (d) collapse of I-35 W bridge in Minneapolis, Minnesota, 2007; (e) inadequate inspection of rails and switches led to train derailment and sulfuric acid spill in Farragut, Tennessee, 2002. (d) (e)

for stronger, damage-tolerant materials that are formed without discontinuities. As emphasis is placed on better raw material quality control, and higher quality manufacturing processes and workmanship, the designer’s requirement for sound material must be verified by NDT.

Public Demands for Greater Safety The demands and expectations of the public for safety are apparent everywhere. The record of the courts in granting high awards to injured people points to the high cost that can result if there is a risk of product failure. The activities of the

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National Safety Council, UL (formerly Underwriters Laboratories, Inc.), the United States Environmen- tal Protection Agency (EPA), the Federal Aviation Administration in the US, and the work of similar agencies abroad, are only a few of the ways in which this demand for safety is expressed. This demand for personal safety has been a strong force in the development of nondestructive tests. Costs of Failure Aside from awards to the injured and costs to the public for collateral effects of large system or structure failure, the cost of failure to a company is significant. Some important reasons are (1) costs of materials and labor; (2) costs of complex parts; (3) costs due to the complexity of assemblies; (4) risk that failure of one part will cause failure of others; and (5) part failure shutting down an entire high-speed, integrated production line. The economics of just-in-time and lean manufacturing place great emphasis on maintaining uninterrupted equipment performance. Loss of such production is one of the greatest losses from part failure. APPLICATIONS OF NONDESTRUCTIVE TESTING Nondestructive testing is a branch of the materials sciences concerned with all aspects of the uniformity, quality, and serviceability of materials and structures. The science of nondestructive testing incorporates all technology for detection and measurement of significant properties, including discontinuities, in items ranging from research specimens to finished hardware and products. By definition, nondestructive techniques are the means by which materials and structures may be inspected without disruption or impairment of serviceability. By using nondestructive testing, internal properties of hidden discontinuities are revealed or inferred through appropriate techniques. Nondestructive testing is vital in effective research, development, design, and manufacturing. Only with nondestructive testing can the benefits of materials science be realized. The information required to appreciate the scope of nondestructive testing is available in many publications.

CLASSIFICATION OF METHODS NDT method can be characterized in terms of five principal factors: (1) energy source or medium used to probe object (such as X-rays, ultrasonic waves, or thermal radiation); (2) nature of the signals, image, and/or signature resulting from interaction with the object (attenuation of X-rays or ref lection of ultrasound); (3) means of detecting or sensing resultant signals (photoemulsion, piezoelectric crystal, or inductance coil); (4) means of indicating and/or recording signals (meter reading, signal display, or image); and (5) basis for interpreting the results (direct or indirect indication, qualitative or quantitative, and pertinent dependencies). The objective of each method is to provide information about the following material parameters: 1. discontinuities and separations (cracks, voids, inclusions, delaminations, others); 2. structure or malstructure (crystalline structure, grain size, segregation, misalignment, others); 3. dimensions and metrology (thickness, diameter, gap size, discontinuity size, others); 4. physical and mechanical properties (reflectivity, conductivity, elastic modulus, sonic velocity, others); 5. composition and chemical analysis (alloy identification, impurities, elemental distributions, others); 6. stress and dynamic response (residual stress, crack growth, wear, vibration, others); 7. signature analysis (image content, frequency spectrum, field configuration, others). Terms in this block are defined in Table 1 with respect to specific objectives and specific attributes to be measured, detected, and defined. Methods that use electromagnetic radiation (Table 2) can be divided according to the segment of the spectrum each uses as interrogating energy: radar, thermography, visual testing, and X-radiography (Figure 3). Methods using vibration and ultrasound are in a different spectrum—the acoustic spectrum. The limitations of a method include conditions required by that method, conditions to be met for technique application (access, physical contact, preparation, or others), and requirements to adapt

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the probe or probe medium to the object examined. Other factors limit the detection and/or character- ization of discontinuities, properties, and other attributes and limit interpretation of signals or images. Classification Relative to Test Object Nondestructive testing techniques may be classified according to how they detect indications relative to the surface of a test object. Surface methods include penetrant testing, visual testing, grid and moiré testing, holography, and shearography. Surface/ near-surface methods include tap, potential drop, magnetic particle, and electromagnetic testing. When surface or surface/near-surface methods are applied during manufacturing, they provide preliminary assurance that volumetric methods performed on the completed object or component

will reveal few, if any, rejectable discontinuities, that is, f laws. Volumetric methods include radiography, tomography, ultrasonic testing, bond testing, acoustic emission testing, certain infrared thermographic techniques, and less familiar methods such as acoustoultrasonic testing and magnetic resonance imaging. Through-boundary methods described include leak testing, some infrared thermographic techniques, airborne ultrasonic testing, and certain techniques of acoustic emission testing. Other less easily classified methods are material identification, vibration analysis, and strain gauging. No one nondestructive testing method is all revealing. That is not to say that one method or technique of a method cannot be adequate for a specific object or component. However, in most cases, it takes a series of test methods to do a

Table 1 Objectives of nondestructive testing methods Discontinuities and separations

Objectives

Attributes Measured or Detected

Surface anomalies

roughness; scratches; gouges; crazing; pitting; inclusions and imbedded foreign material

Surface connected anomalies

cracks; porosity; pinholes; laps; seams; folds; inclusions

Internal anomalies

cracks; separations; hot tears; cold shuts; shrinkage; voids; lack of fusion; pores; cavities; delaminations; disbonds; poor bonds; inclusions; segregations

Structure

Objectives

Attributes Measured or Detected

Microstructure

molecular structure; crystalline structure and/or strain; lattice structure; strain; dislocation; vacancy; deformation grain structure, size, orientation, and phase; sinter and porosity; impregnation; filler and/or reinforcement distribution; anisotropy; heterogeneity; segregation leaks (lack of seal or through-holes); poor fit; poor contact; loose parts; loose particles; foreign objects

Matrix structure

Small structural anomalies

Gross structural anomalies

assembly errors; misalignment; poor spacing or ordering; deformation; malformation; missing parts

Dimensions and metrology

Objectives

Attributes Measured or Detected

Displacement; position

linear measurement; separation; gap size; discontinuity size, depth, location, and orientation

Dimensional variations

unevenness; nonuniformity; eccentricity; shape and contour; size and mass variations

Thickness; density

film, coating, layer, plating, wall, and sheet thickness; density or thickness variations

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Table 1 Objectives of nondestructive testing methods (continued) Physical and mechanical properties

Objectives

Attributes Measured or Detected

Electrical properties

resistivity; conductivity; dielectric constant and dissipation factor

Magnetic properties

polarization; permeability; ferromagnetism; cohesive force

Thermal properties

conductivity; thermal time constant and thermoelectric potential

Mechanical properties

compressive, shear, and tensile strength (and moduli); Poisson’s ratio; sonic velocity; hardness; temper and embrittlement

Surface properties

color; reflectivity; refraction index; emissivity

Chemical composition and analysis

Objectives

Attributes Measured or Detected

Elemental analysis

detection; identification, distribution, and/or profile

Impurity concentrations

contamination; depletion; doping and diffusants

Metallurgical content

variation; alloy identification, verification, and sorting

Physiochemical state

moisture content; degree of cure; ion concentrations and corrosion; reaction products

Stress and dynamic response

Objectives

Attributes Measured or Detected

Stress; strain; fatigue

heat treatment, annealing, and cold work effects; residual stress and strain; fatigue damage and life (residual)

Mechanical damage

wear; spalling; erosion; friction effects

Chemical damage

corrosion; stress corrosion; phase transformation

Other damage

radiation damage and high frequency voltage breakdown

Dynamic performance

crack initiation and propagation; plastic deformation; creep; excessive motion; vibration; damping; timing of events; any anomalous behavior

Signature analysis

Objectives

Attributes Measured or Detected

Electromagnetic field

potential; strength; field distribution and pattern

Thermal field

isotherms; heat contours; temperatures; heat flow; temperature distribution; heat leaks; hot spots noise; vibration characteristics; frequency amplitude; harmonic spectrum and/or analysis; sonic and/or ultrasonic emissions

Acoustic signature

Radioactive signature

distribution and diffusion of isotopes and tracers

Signal or image analysis

image enhancement and quantization; pattern recognition; densitometry; signal classification, separation and correlation; discontinuity identification, definition (size and shape), and distribution analysis; discontinuity mapping and display

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Table 2 Nondestructive test methods and corresponding parts of electromagnetic spectrum

Approximate Wavelengths (m)

Approximate Frequencies (Hz)

Interrogating Energy

Test Method

10 –16 to 10 –8 10 –8 to 10 –7

10 24 to 10 17 10 17 to 10 15

X-rays or gamma rays Ultraviolet radiation Light (visible radiation) Heat or thermal radiation

radiographic testing (RT) various minor methods a

4 × 10 –7 to 7 × 10 –7

10 15

visual testing (VT)

10 –6 to 10 –3 10 –3 to 10 1

10 15 to 10 11 10 11 to 10 7

infrared and thermal testing (IR) radar and microwave methods

Radio waves

a. Ultraviolet radiation is used in various methods: (1) viewing of fluorescent indications in liquid penetrant testing and magnetic particle testing; (2) lasers and optical sensors operating at ultraviolet wavelengths.

Radiation wavelength (nm)

10 6

10 5

10 4

10 3

10 2

10 1

10

10 –1

10 –2

10 –3

10 –4

10 –5

10 –6

X-rays

Cosmic rays

Radio

Infared

Ultraviolet

Gamma rays

Visible light

10 –9

10 –8

10 –7

10 –6

10 –5

10 –4

10 –3

10 –2

10 –1

1

10

10 2

10 3

Photon energy (MeV)

Figure 3 Electromagnetic spectrum.

complete nondestructive test of a test object. For example, if surface cracks must be detected and eliminated and the test object is ferromagnetic, then magnetic particle testing would be the obvious choice. If that same material was aluminum or titanium, then the choice would be penetrant or electromagnetic testing. However, for either of these situations, if internal discontinuities were sought, then ultrasonic or radiographic testing would be selected. The exact technique in either case would depend on the thickness and nature of the material and the type or types of discontinuities that must be detected.

added process in the manufacturing activity of a product. As a result, NDT can be vulnerable to compromise for the illusion of profit. However, referring to the “Purpose of Nondestructive Testing” discussed earlier, there are economic reasons for performing NDT that do add value to the product, not the least of which are reliability and high-quality reputation. Additionally, the reduction in the risk of failure has significant economic benefits that can be calculated. The economic benefit of NDT is acknowledged in many industries such as aerospace, electronics, petrochemical, and infastructure. The profit from NDT is realized when the cost of not performing NDT outweighs the cost of NDT. Performed in conjunction with statistical quality control methods, NDT provides critical information for continuous process improvement, a hallmark of good manufacturing. Nondestructive testing should be used as a control mechanism to ensure that manufactur- ing processes are within design performance

VALUE OF NONDESTRUCTIVE TESTING

The contribution of nondestructive testing to profits is reviewed and justified by Emmanuel Papadakis (Papadakis 2006). Industrial engineering practice has been known to consider NDT as a non-value

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requirements. Nondestructive testing should not be used to obtain quality at the end of manufacturing. This approach will ultimately increase production costs. When used properly, nondestructive testing saves money for the manufacturer. Rather than costing the manufacturer money, properly implemented nondestructive testing will add profits to manufacturing. NONDESTRUCTIVE TEST METHODS To optimize nondestructive testing, it is necessary first to understand the principles and applications of all the methods. The following section brief ly describes major methods and the applications associated with them. Visual Testing Principles . Visual testing (Figure 4) is the observa- tion of a test object, either directly with the eyes or indirectly using optical instruments, by an inspector to evaluate the presence of surface anomalies and the object’s conformance to specifi- cation. Visual testing is the first nondestructive test method applied to an item. The test procedure is to clear obstructions from the surface, provide adequate illumination and observe. A prerequisite necessary for competent visual testing of an object is knowledge of the manufacturing processes by which it was made, of its service history, and of its potential failure modes, as well as related industry experience. Applications . Visual testing is widely used on a variety of objects to detect surface anomalies associated with various structural failure mechanisms. Even when other nondestructive tests are performed, visual tests often provide a useful supplement. When the eddy current testing of process tubing is performed, for example, visual testing is often performed to examine the surface more closely. The following discontinuities may be detected by a simple visual test: surface disconti- nuities, cracks, misalignment, warping, corrosion, wear, and dents. Liquid Penetrant Testing Principles . Penetrant testing (Figure 5) reveals discontinuities open to the surfaces of solid and nonporous materials. Indications of a wide variety

of discontinuity sizes can be found, regardless of the configuration of the test object and regardless of discontinuity orientations. Liquid penetrants seep into various types of minute surface openings by capillary action. The cavities of interest can be very small, often invisible to the unaided eye. The ability of a given liquid to f low over a surface and enter surface cavities depends on the following conditions: cleanliness of the surface, surface tension of the liquid, configuration of the cavity, contact angle of the liquid, ability of the liquid to wet the surface, cleanliness of the cavity, and size of the surface opening of the cavity. Applications . The principal industrial uses of penetrant testing include post-fabrication testing, receiving testing, in-process testing and quality control, testing for maintenance and overhaul in the transportation industries, in-plant and machinery maintenance testing, and testing of large components. The following are some of the typically detected discontinuities: surface discontinuities, seams, cracks, laps, porosity, and leak paths.

Figure 4 Visual testing using a portable videoscope.

Figure 5 Liquid penetrant indication of cracking.

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