1、Copyrighted material licensed to Stanford University by Thomson Scientific(),downloaded on Oct-05-2010 by Stanford University User.No further reproduction or distribution is permitted.Uncontrolled when printed.AN AMERICAN NA TIONALST ANDARDMETRIC HEAVYHEX FLANGESCREWSASME B18.2.3.9M-2001Revision of
2、ANSI/ASME B18.2.3.9M-1984(R1995)Copyrighted material licensed to Stanford University by Thomson Scientific(),downloaded on Oct-05-2010 by Stanford University User.No further reproduction or distribution is permitted.Uncontrolled when printed.Date of Issuance:September 17,2001This Standard will be re
3、vised when the Society approves the issuance of anew edition.There will be no addenda issued to this edition.ASME will issue written replies to inquiries concerning interpretations oftechnical aspects of this Standard.ASME is the registered trademark of The American Society of Mechanical Engineers.T
4、his code or standard was developed under procedures accredited as meeting the criteria forAmerican National Standards.The Standards Committee that approved the code or standardwas balanced to assure that individuals from competent and concerned interests have had anopportunity to participate.The pro
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9、in any form,in an electronic retrieval system or otherwise,without the prior written permission of the publisher.The American Society of Mechanical EngineersThree Park Avenue,New York,NY 10016-5990Copyright 2001 byTHE AMERICAN SOCIETY OF MECHANICAL ENGINEERSAll Rights ReservedPrinted in U.S.A.Copyri
10、ghted material licensed to Stanford University by Thomson Scientific(),downloaded on Oct-05-2010 by Stanford University User.No further reproduction or distribution is permitted.Uncontrolled when printed.FOREWORDAmerican National Standards Committee B18 for the standardization of bolts,screws,nuts,r
11、ivets,and similar fasteners was organized in March 1922 as Sectional CommitteeB18 under the aegis of the American Engineering Standards Committee(later the AmericanStandards Association,then the United States of America Standards Institute and,as ofOctober 6,1969,the American National Standards Inst
12、itute,Inc.),with the Society ofAutomotive Engineers and the American Society of Mechanical Engineers as joint sponsors.Subcommittee 2 was subsequently established and charged with the responsibility for technicalcontent of standards covering wrench head bolts and nuts.At its meeting on December 4,19
13、74,Committee B18 authorized preparation of a seriesof standards for metric fasteners.Subcommittee 2 was assigned responsibility for developingstandards for metric hex bolts,screws,and nuts.Following issuance of ANSI B18.2.3.4M-1979,interest developed in the farm equipment,heavy truck,and off-road ve
14、hicles industries for a second series of metric hex flange screwshaving a head widths across flats series equal to those of metric hex cap screws.Duringthe analytical research study to optimize head proportions of hex flange screws(refer tothe Foreword of ASME B18.2.3.4M-2000),this larger head serie
15、s was also investigated,and appropriate values for the various head characteristics were established for screw sizesM10 through M20.This new design of metric heavy hex flange screws was submitted by the United Statesof America/Canada to ISO/TC2 at its May 1982 meetings.TC2 accepted the proposal anda
16、uthorized development of International Organization for Standardization(ISO)standards.After these ISO decisions,Subcommittee 2 drafted this Standard.This Standard was approved by letter ballot of the ASME B18 Standards Committee onApril 18,1983,and was subsequently approved by the American Society of MechanicalEngineers and submitted to the American National Standards Institute for designation asan American National Standard.This was granted on March 23,1984.The Standard wasreaffirmed in 1995.Th
