ISO 657 (Hot-rolled steel sections) is an ISO standard that specifies the tolerances for hot-finished circular, square and rectangular structural hollow sections and gives the dimensions and sectional properties for a range of standard sizes. This first edition as an International Standard constitutes a technical revision of ISO Recommendation R 657-1:1968. ISO 657 consists of 21 parts integrating any shapes of sections. ISO 657-1 specifies dimensions of hot-rolled equal-leg angles. Amendments ISO 657-2:1989 ISO 657-5:1976 ISO 657-11:1980 ISO 657-14:2000 Revisions ISO/DIS 12633-2 ISO 657-14:1982 ISO 657-15:1980 ISO 657-16:1980 ISO 657-18:1980 ISO 657-19:1980 ISO 657-21:1983 References ISO Catalogue in the ISO website 00657