The tables of Properties and Dimensions in Part 6 of the Handbook provide values of the depth (d), width (b) and wall thickness (t) of square and rectangular hollow structural sections (HSS). Values of the exterior and interior corner radii are not tabulated, however, mainly because these dimensions are not listed in CSA standard G40.20.
Section properties in the Handbook tables are based on an interior corner radius taken equal to the wall thickness, and on an exterior corner radius taken equal to twice the wall thickness. The respective corner radii are illustrated on the figure below. For HSS produced to ASTM A500, the radii are based on the design wall thickness, taken equal to 90% of the nominal value.
The maximum exterior corner radius permitted by the G40.20 standard varies from two to four times the wall thickness, depending on the section perimeter and wall thickness. Further information on corner radius tolerances can be found in Part 6 of the Handbook, including tolerances for HSS produced to ASTM A500 and A1085.