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A 11 10 3 073222 TECH HAG. NATL INST OF STANDARDS! » fe* 1 All 103073222 to NBS SPECIAL PUBLICATION 589 U.S. DEPARTMENT OF COMMERCE / National Bureau of Standards Eddy Current Nondestructive Testing NATIONAL BUREAU OF STANDARDS The National Bureau of Standards' was established by an act ot Congress on March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology and facilitate their effective application for public benefit. To this end, the Bureau conducts research and provides: (1) a basis for the Nation's physical measurement system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety. The Bureau's technical work is per- formed by the National Measurement Laboratory, the National Engineering Laboratory, and the Institute for Computer Sciences and Technology. THE NATIONAL MEASUREMENT LABORATORY provides the national system of physical and chemical and materials measurement; coordinates the system with measurement systems of other nations and furnishes essential services leading to accurate and uniform physical and chemical measurement throughout the Nation's scientific community, industry, and commerce; conducts materials research leading to improved methods of measurement, standards, and data on the properties of materials needed by industry, commerce, educational institutions, and Government; provides advisory and research services to other Government agencies; develops, produces, and distributes Standard Reference Materials; and provides calibration services. The Laboratory consists of the following centers: Absolute Physical Quantities 2 — Radiation Research — Thermodynamics and Molecular Science — Analytical Chemistry — Materials Science. THE NATIONAL ENGINEERING LABORATORY provides technology and technical ser- vices to the public and private sectors to address national needs and to solve national problems; conducts research in engineering and applied science in support of these efforts; builds and maintains competence in the necessary disciplines required to carry out this research and technical service; develops engineering data and measurement capabilities; provides engineering measurement traceability services; develops test methods and proposes engineering standards and code changes; develops and proposes new engineering practices; and develops and improves mechanisms to transfer results of its research to the ultimate user. The Laboratory consists of the following centers: Applied Mathematics — Electronics and Electrical Engineering 2 — Mechanical Engineering and Process Technology 2 — Building Technology — Fire Research — Consumer Product Technology — Field Methods. THE INSTITUTE FOR COMPUTER SCIENCES AND TECHNOLOGY conducts research and provides scientific and technical services to aid Federal agencies in the selection, acquisition, application, and use of computer technology to improve effectiveness and economy in Government operations in accordance with Public Law 89-306 (40 U.S.C. 759), relevant Executive Orders, and other directives; carries out this mission by managing the Federal Information Processing Standards Program, developing Federal ADP standards guidelines, and managing Federal participation in ADP voluntary standardization activities; provides scientific and technological advisory services and assistance to Federal agencies; and provides the technical foundation for computer-related policies of the Federal Government. The Institute consists of the following centers: Programming Science and Technology — Computer Systems Engineering. 'Headquarters and Laboratories at Gaithersburg, MD, unless otherwise noted; mailing address Washington, DC 20234. 2 Some divisions within the center are located at Boulder, CO 80303. National Bureau of Standards Library, £-01 Admin. Bldg, FEB 2 7 1981 not o.cc. -£j <c Eddy Current Nondestructive Testing no. S~$9 C. 3~ Proceedings of the Workshop on Eddy Current Nondestructive Testing, held at the National Bureau of Standards, Gaithersburg, Maryland, on November 3-4, 1977 Edited by: George M. Free Center for Absolute Physical Quantities National Measurement Laboratory National Bureau of Standards Washington, DC 20234 \ JCO iptrml ptiJhhCa.il 0 U.S. DEPARTMENT OF COMMERCE, Philip M. Klutznick, Secretary Jordan J. Baruch, Assistant Secretary for Productivity, Technology and Innovation j NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director Issued January 1981 Library of Congress Catalog Card Number: 80-600172 National Bureau of Standards Special Publication 589 Nat. Bur. Stand. (U.S.), Spec. Publ. 589, 153 pages (Jan. 1981) CODEN. XNBSAV U.S. GOVERNMENT PRINTING OFFICE WASHINGTON: 1981 For sale l>y the Superintendent of Documents, U.S. Government Printing Office Washington. D.C. 20402 - Price $5.50 FOREWORD Although testing with eddy cur- These Proceedings are a record of that rents is regarded as one of the major Workshop. methods for nondestructive inspection, many people in the industry regard The purposes of the Workshop were to this technique as one that offers much (1) review the current status of eddy cur- greater potential than is presently rent measurement methodology and applica- realized. It is now used primarily tions, (2) define the directions for im- for the sorting of alloys by conduct- proved techniques and applications, and ivity measurements and for the inspec- (3) assess the needs for work on standards tion of relatively thin conducting mate- and underlying science to address present rial; thin-walled tubing constitutes a and future problems. The attendees were major inspection item for eddy current drawn from industry, university, and gov- techniques. ernment. We have thanked them all indi- vidually, but it is appropriate here also In the Nondestructive Evaluation to express our appreciation to them again (NDE) Program at the National Bureau of and particularly to the speakers. Standards, we are working to improve the reliability of nondestructive measure- I also wish to express my apprecia- ments. The present effort in eddy cur- tion to the planners of the Workshop, rent testing is directed primarily at Norman Belecki, George Free, and Barry conductivity measurements; a measurement Taylor of the NBS Electricity Division? service and standard reference materials George Birnbaum, of the NDE Program; and are planned to help the industry improve Robert Green of the Johns Hopkins Uni- this type of NDE measurements. Looking versity. I am confident that these Pro- beyond that, however, we at NBS agree ceedings will serve their intended pur- that new ideas and developments can lead poses and help the industry and NBS de- to greater utilization of eddy current fine fruitful areas for additional work methods. One means to examine that to improve eddy current nondestructive potential was a Workshop on Eddy Current testing. Nondestructive Testing; the Workshop was held at NBS on November 3 and 4, 1977, under the joint sponsorship of the NBS Electricity Division and the NDE Program. Harold Berger Program Manager Nondestructive Evaluation February 1978 iii PREFACE The intent of these Proceedings is Due to the method of printing the pro- to provide a record of the NBS Workshop ceedings, not all pictures and diagrams on Eddy Current Nondestructive Testing. turned out to be of equal clarity. I apol- With the excpetion of the first paper, ogize beforehand to those authors whose an overview of eddy current testing by pictures or diagrams are not of the excel- Dr. Robert McMaster, each paper present- lent quality which the participants viewed ed was followed by a period of discus- at the workshop. sion. The Proceedings followed the same format. Unfortunately, the com- ments of participants could not be at- tributed in all cases, but where it is possible the authors of the many com- ments, questions, and ideas are noted. Some editing of the discussion periods was done, consequently the discussion George M. Free periods are not "verbatim." Editor v TABLE OF CONTENTS PAGE FOREWORD iii Harold Berger PREFACE v ABSTRACT vi i i THE HISTORY, PRESENT STATUS, AND FUTURE DEVELOPMENTS OF EDDY CURRENT TESTS 1 Robert C. McMaster EDDY CURRENT TESTING: PRESENT AND FUTURE APPLICATIONS IN THE FERROUS METAL INDUSTRY 33 Richard B. Moyer EDDY CURRENT STANDARDS IN NONFERROUS METALS 39 Carlton E. Burley EDDY CURRENT INSPECTION OF GAS TURBINE BLADES 45 Robert A. Betz EDDY CURRENT EXAMINATION IN THE NUCLEAR INDUSTRY 49 Allen E. Wehrmeister EDDY CURRENT INSPECTION SYSTEMS FOR STREAM GENERATOR TUBING IN NUCLEAR POWER PLANTS 57 Clyde J. Denton USE OF ROUND ROBIN TESTS TO DETERMINE EDDY CURRENT SYSTEM PERFORMANCE 63 E. R. Reinhart EDDY CURRENT TESTING IN GOVERNMENT 77 Patrick C. McEleney CURRENT STATUS AND FUTURE DIRECTIONS OF EDDY CURRENT INSTRUMENTATION 81 Tracy W. McFarlan MULTIFREQUENCY EDDY CURRENT INSPECTION TECHNIQUES 87 Hugo L. Libby PULSED EDDY CURRENT TECHNIQUES FOR NONDESTRUCTIVE EVALUATION . 107 D. L. Waidelich THE INTRODUCTION OF SIGNAL PROCESSING TECHNIQUES TO EDDY CURRENT INSPECTION 113 E. E. Weismantel DEVELOPMENT OF NON-FERROUS CONDUCTIVITY STANDARDS AT BOEING 121 Arthur Jones NBS EDDY CURRENT STANDARDS PROGRAM 133 George Free ELECTROMAGNETIC THEORY AND ITS RELATIONSHIP TO STANDARDS 137 Arnold H. Kahn and Richard D. Spal DISCUSSION: NEW SCIENCE DIRECTIONS AND OPPORTUNITIES CONCLUDED FROM WORKSHOP SESSIONS 143 Leader: Robert E. Green DISCUSSION: NEW DIRECTIONS FOR STANDARDS CONCLUDED FROM WORKSHOP SESSIONS 149 Leader: Norman
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