272 (ISO International Standard INTERNATIONAL ORGANIZATION FOR STANDARDIZATION+MEXKAYHAPOAHAH OPTAHM3ALWA HO CTAHAAPTW3ALWM+ORGANISATION INTERNATIONALE DE NORMALISATION Fasteners -- Hexagon products -- Widths across flats Elements de fixation -Produits hexagonaux.--Dimensions des surplats Second edition - 1982-01-15 UDC 621.882.1 Ref. No. ISO 272-1982 (E) ISO 272-1982 (E) Descriptors : fasteners, screws, hexagonal head screws, bolts, nuts (fasteners), hexagonal nuts, width across flats, dimensions. Price based on 3 pages Foreword ISo (the International Organization for Standardization) is a woridwide federation of national standards institutes (iso member bodies). The work of developing Inter- national StandardsiscarriedoutthroughIsotechnical committees,Everymember bodyinterestedina subjectforwhichatechnical committeehasbeenset uphasthe right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with Iso, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the Iso Council. International Standard ISO 272 was developed by Technical Committee ISO/TC 2, Fasteners. The first edition (ISo 272-1979) had been approved by the member bodies of the following countries : Australia Ireland Romania Belgium Italy South Africa, Rep. of Canada Korea, Dem. P. Rep. of Spain Czechoslovakia Korea, Rep. of Sweden Denmark Mexico Switzerland Finland Netherlands Turkey Germany, F. R. New Zealand United Kingdom Hungary Norway USA India Poland Yugoslavia The member bodies of the following countries expressed disapproval of the document on technical grounds : France USSR This second edition, which cancels and replaces Iso 272-1979, incorporates draft Addendum1,whichwascirculatedtothememberbodiesinMarch1980andhasbeen approved by the member bodies of the following countries : Australia India Poland Austria Ireland Romania Belgium Italy South Africa, Rep. of Czechoslovakia Japan Spain Egypt, Arab Rep. of Korea, Dem. P. Rep. of Sweden Finland Korea, Rep.of Switzerland France Netherlands United Kingdom Germany, F. R. New Zealand USA Hungary Norway The member bodies of the folowing countries expressed disapproval of the document on technicalgrounds : Canada Denmark USSR @ International Organization for Standardization, 1982 Printed in Switzerland ISO272-1982(E) INTERNATIONAL STANDARD Fasteners s - Hexagon products -- Widths across flats 1 Scope and field of application This International Standard specifies widths across flats for hexagon products, for example hexagon head bolts and screws, hexagon nuts and hexagon flanged bolts, screws and nuts, to be used in the respective product standards. It also specifies a logical ratio between underhead (or nut) bearing area (which determines the magnitude of the compressive stress on governs the clamping force which can be developed by tightening the fastener for any particular strength class of fastener). This available to engineering designers. 1