LOCKWASHERS (INCHSERIES)
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FOREWORD
washers was organized in March 1926 as Sectional Commitee B27 under the aegis of the American National Standards Commitee B27 for the standardization of plain and lockas of October 6 1969 the American National Standards Institute Inc.) with the Society American Standards Association (later the United States of America Standards Institute and and machine rings. sponsors. Since 1950 this Commite has been responsible for the standardization of washers
In May 1928 the B27 Committe established two submittees to carry on developmentstandard for helical spring-lock washers circulated for industry ment in November 1931 work Submittee 1* on plain washers and Submittee 2* on lock washers. A tentativebut failed to achieve acceptance. Hence Committee activity was dormant for some years.
In 1940 the B27 Committee was reorganized and Submittce 2 proceeded to drafta proposal covering three series of helical spring-lock washers designated light medium and heavy. In 1943 this proposal was amended to include the extra-heavy series washersand following approval by the B27 Committee and sponsor organizations was acceptedas an American Standard under the designation ASA B27.1-1944.
During the ensuing years minor refinements to the hardness requirements and methodsof test were considered. In December 1948 the B27 Commitee accepted. in principle. cxpansion of the Standard to cover helical spring-lock washers made from materials otherthan carbon steel the inclusion of specifications for tooth-lock washers and both helicalspring- and tooth-lock washers and machine screw assemblies. A draft proposal incorporating requirements applicable to corosionreistant steelphosphor bronze silicon ronzealmnum-zinc alloy K-monel helical spring-lock washers and the other new products wasCommittee and sponsors this proposal was forwarded to the American Standards Associationand declared an American Standard on May 22 1950.
From 1951 through 1958 Submittee 2 held five meetings at which members agreedto extend the light and heavy series helical spring-lock washers to include sizes 1% in. through 3 in. establish tolerances on the nominal thickness of helical spring-lock washers and recognize hardened screw and lock washer assemblies. A formal draft dated June 1957. was approved by letter ballot of the B27 Committe and the sponsor organizations and submitted to the American Standards Association for designation as an Amcrican Standard.This was granted on November 3 1958.
From 1959 through 1961 a number of changes were remended by the Helical Washermore exacting demands of consumer industries. Also at a meting held on November 28. 1961 the B27 Committee recognized the desirability of publishing the screw and washerto joint approval by the B27 Committee and affected submittees thereof. Subsequently. assemblies as a separate document under the jurisdiction of the B18 Committee but subjecta draft proposal deleting the coverage on screw and washer assemblies and incorporating
revisions to the helical spring-lock washers was prepared. The latter included changing the designation of medium series to regular series and extra-heavy series to extra-duty series and the addition of the high-collar scries for use with socket hcad cap screws. Followingacceptance by the submitte the proposal was letter balloted to the B27 Committe on November 18 1963. It was then approved by the sponsors and the American StandardsAssociation and officially granted recognition as an American Standard on September 20 1965.
After continued studies conducted by the Helical Washer Institute the group submitedfurther remendations for changes to the Standard at a meeting of the American National Standards Commitee B27 in October 1969. Submitte 1 then prepared a proposal inMay 1970 to incorporate the changes to helical pring-lock washers. These changes consistedof deleting coverage for the light series and Type 420 corrosion-resistant steels adding control on section-er radius. adjusting the inside diameter and relegating the heavyseries to “Not Remended for Ncw Applications" status. Other minor corrections todimensional data and extensive editorial refinements were also included. This draft was approved by leter ballot of Standards Commitee B27 on August 11 1970. Subsequent tothe inclusion of additional editorial refinements the proposal was accepted by the sponsor organizations and submited to American National Standards Institute for designation as anStandards Commitee B27 the washer activity was transfered to American National StandardsCommittee B18. Submittee 1 of B27 was redesignated as Submittee 21 of StandardsCommittce B18. This is the reason for the redesignation of the Standard. This revision was approved as an American National Standard on April 28 1972. In 1983 the B18.21.1Submittee reaffirmed the 1972 standard.
was pleted. This revised draft was reviewed by the members of Submittee 21 at On December 1 1985 the first draft containing revisions to the 1972 reaffirmed standardthe December 1985 meeting. Between the meetings in December 1985 and December 1987 the Standard was reviewed by the Submittee and refinements were made. A motion towere reviewed and editorial changes were made. At the May 1989 meeting a revised draf ballot the Standard was made in December 1987. By December 1988 all ballot mentsdated May 7 1989 was submitted for publication. Some of the changes for the helicalafter the allowable radi dimension was subtracted lowering of the Rockwell hardness for spring-lock washer included a graphic illustration with tables to help detine the flat facecarbon steel the addition of a table of hardness values for other materials and a table covering materials. Dimensional changes were made to the inside and outside diameters forregular heavy and extra-duty series % in. through 1 in. and up to the 3 in. size forhigh-collar. The regular hcavy. and extra duty tables were expanded to include thc sizes from 1% in. up to 3 in. The data for tooth-lock washers remained the same. Followingapproval by ASME. the document was submited to the American National Stuandards Institute and was aproved as an American National Standard on July 5 1990.
% in.and larger hlical spring-lock washers was developed to corret anexcessivereduction On December 9. 1992 a proposal to revise the dimensions of the inside diameter forin the tolerance for these sizes. In addition the trapezoid dimensions were replaced withthe formula used in prior standards; several materials and hardness values were added; paragraphs covering lot size inspection and quality assurance requirements and inspectioncharacteristics were added; and editorial changes were madc. The proposal was sent outfor balloting and at the December 7 1993 meeting. ments were reviewed and acted upon as needed. Following approval by ASME the document was submitted to the AmericanNational Standards Institute and was approved as an American National Standard on October 6 1994.
On December 4 1995 a proposal was developed to revise and clarify several items inthis Standard. For helical spring-lock washers the changes included adding clearance to the washer inside diameter requiring heavier coatings such as ones that are mechanically
galvanized moving the decarburization measuring requirement into the proper designatedhead. and correcting illustrations above tables.For tooth-lock washers the changes includedclarifying the wording used in the measurement of the tooth projctions on both sides removing the need for twist testing. and changing some thickness dimensions in Tables 6and 8 and the Notes for Table 9. In addition this Standard was revised to conform withthe standard format of B18 documents.
This new edition of the Standard was approved as an American National Standard onNovember 2 1999.
