3-8M_R1991_E1981.pdf

A M E R I C A N N A T I O N A L S T A N D A R D Metric Hex Lag Screws ANSI B18.2.3.8M-1981(REVISION OF ANSI 818.2.3.8M-19793 Government Key Words:Screw,Lag,Hex Head-Metric REAFFIRMED 1999 FOR CURRENT COMMITTEE PERSONNEL PLEASE SEE ASME MANUAL AS-I 1 SECNt IANlA I SOCIETY OF AUTOMOTIVE ENGINEERS THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS PUBLISHED BY T H E A M E R I C A N S O C I E T Y O F M E C H A N I C A L E N G I N E E R S United Engineering Center 345 East 47th Street New York,N.Y.1001 7 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.This code or standard was developed under procedures accredited as meet-ing the criteria for American National Standards.The Consensus Committee that approved the code or standard was balanced to assure that individuals from competent and concerned interests have had an opportunity to partici-pate.The proposed code or standard was made available for public review and comment which provides an opportunity for additional public input from industry,academia,regulatory agencies,and the public-at-large.ASME does not“approve,”“rate,”or “endorse”any item,construction,proprietary device,or activity.ASME does not take any position with respect to the validity of any patent rights asserted in connection with any items mentioned in this docu-ment,and does not undertake to ensure anyone utilizing a standard against liability for infringement of any applicable Letters Patent,nor assume any such liability.Users of a code or standard are expressly advised that determina-tion of the validity of any such patent rights,and the risk of infringement of such rights,is entirely their own responsibility.Participation by federal agency representative(s)or person(s)affiliated with industry is not to be interpreted as government or industry endorsement of this code or standard.Date of Issuance:August 31,1981 No part of this document may be reproduced in any form,in an electronic retrieval system or otherwise,without the prior written permission of the publisher.Copyright 0 1981 by THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS All Rights Reserved Printed in U.S.A.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.FOREWORD American National Standards Committee B18 for the standardization of bolts,screws,nuts,rivets and similar fasteners was organized in March 1922,as Sectional Committee B18 under the aegis of the American Engineering Standards Committee (later the American Standards Association,then the United States of American Standards Institute and,as of October 6,1969,the American National Standards Institute,Inc.),with the Society of Automotive Engineers and the American Society of Mechanical Engineers as joint sponsors.Subcommittee 2 was subsequently established and charged with the responsibility for technical content of standards covering wrench head bolts and nuts.At its meeting on December 4,1974,Committee B18 authorized preparation of a series of standards for metric fasteners.Subcommittee 2 was assigned responsibility for developing standards for metric hex bolts,screws and nuts.At a meeting on September 22,1976,Subcommittee 2 organized the contents of a standard covering eight different hex head screw and bolt products.Actual drafting was postponed until ISO/TC2 could reach final decisions relating to basic dimensions and characteristics of hex bolts,screws and nuts.At ISO/TC2 meetings held in April 1977,final actions were taken.Committee B18 affirmed the TC2 decisions at a meeting on June 29,1977 and drafting of this standard was started.In February 1978,Committee B18 established a cooperative program with the Department of Defense to draft American National Standards for metric fasteners in such a way that they could be used directly by the Government for procurement purposes.The Department of Defense requested that each of the eight products be covered in separate standards,and Subcommittee 2 accepted this approach at its meeting on June 27,1978.This standard was approved by letter ballot of Committee B18 on September 15,1978,and was sub-sequently approved by the secretariat and submitted to the American National Standards Institute for designation as an American National Standard.This was granted on May 17,1979.At its meeting on October 22,1980,Subcommittee 2 approved two technical revisions to the 1979 issue.The 14 mm screw size was discontinued and thread dimensions were modified to improve lag screw performance and to economize production tooling.This revised standard was approved by letter ballot of Committee B18 on November 25,1980,and was approved by the secretariat and submitted to the American National Standards Institute which granted it recognition as an Am