ISO INTERNATIONAL STANDARD 898-7 First edition 1992-11-01 Mechanical properties offasteners Part 7: Torsional test and minimum torques for bolts and screws with nominal diameters 1mm to 10 mm Caracteristiquesmecaniquesdesélementsdefixation Partie7:Essaidetorsion et couples minimauxderupture desvisde diametrenominaldefiletagede1mma10mm Referencenumber ISO 898-7:1992(E) ISO898-7:1992(E) Foreword iso(the International Organization for Standardization)is a woridwide federation ofnational standards bodies (isO memberbodies).Thework of preparing International Standards is normally carriedout through Iso technical committees. Each member body interested in a subject for whichatechnical committee hasbeen established has the rightto be represented on that committee.International organizations,govern- mental and non-governmental,in liaison with iso,alsotakepart inthe work.Isocollaborates closely withthe International Electrotechnical Commission (IEC)on allmatters of electrotechnical standardization. Draft International Standards adopted bythe technical committees are circulated to themember bodies for voting.Publication as an Inter- national Standard requires approval by at least75%of themember bodies castingavote. International Standardiso898-7waspreparedbyTechnical Committee Iso/Tc2,Fasteners,Sub-CommitteesC1,Mechanicalpropertiesof fasteners. iso898 consists of thefoilowingparts,underthegeneral titleMechan- icalpropertiesoffasteners: Part1:Bolts,screwsandstuds Part2:Nutswithspecifiedproofloadvalues-Coarsethread Part5:Setscrewsandsimilarthreadedfastenersnotundertensile stresses - Part6:Nutswithspecifiedproof loadvalues-Finepitchthread Part7:Torsionaltestandminimumtorquesforbolts andscrews - withnominaldiameters1mmto10mm AnnexAof thispartofiso898isforinformationonly. ISO1992 or by any means,electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. CasePostale56·CH-1211Geneve20·Switzerland Printed in Switzerland ii ISO 898-7:1992(E) INTERNATIONALSTANDARD Mechanical properties offasteners Part 7: Torsional test and minimum torques for bolts and screws swith nominal diameters 1 mm to 10 ww 3.2 Scope Apparatus 1 Thispartof iso898specifies atorsionaltestforthe determination of the breaking torque of bolts and screws with nominal diameters 1mmto 10 mm with Test device for torsional test, such as is 3.2.1 propertyclasses8.8to12.9inaccordancewith shown in figure 1. ISO898-1.Thetestappliestoboltsand screwswith thread less than M3 for which no breaking and proof loads are indicatedinIso898-1,aswell astoshort boltsandscrewswithnominal diameters3mmto 3.2.2 Torquemeter,with a scale which shall not ex- 10 mm which cannotbe subjected to atensiletest. ceedthequintuple of the respective minimum breaking torque.Themaximum inaccuracy ofthe The minimum breaking torques are not valid for torquemeter shall be±7%of theminimumbreak- hexagon socket set screws. ingtorquetobetested. Normativereference 2 Thefollowing standard contains provisions which, through reference in this text, constitute provisions 3.3 Test conditions of thispartofIsO898.Atthetimeofpublication,the edition indicated was valid.All standards are sub- The bolt or screw shall be exclusively subjected to jectto revision,andparties to agreementsbasedon torsion whereby the respective minimum breaking this part of iso 898 are encouraged to investigate torque accordingtotable2 shall bereached before thepossibilityofapplyingthemostrecent editionof rupture occurs.The test result shall not be influ- the standard indicated below.Members of iEC and enced by head friction or by thread friction. iso maintainregisters of currently .validInter- national Standards. Iso898-1:1988,Mechanicalpropertiesoffasteners Part 1:Bolts, screws and studs. 3.4 Procedure 3 Torsional test Clamp thebolt or screw into thetest device overat least twofull threads,having a free thread length of 3.1 Principle at least one thread diameter present between the head of the bolt or