Grades
IS 4923 grades are designated by minimum yield strength: YSt 210, YSt 240, YSt 310 and higher strength grades in current editions. YSt 310 is a frequent reference for structural SHS/RHS in building and fabrication drawings.
Size designation
Hollow sections are written outside dimensions × wall thickness — for example SHS 50 × 50 × 3.2 or RHS 96 × 48 × 3.2. State length (commonly 6 m mill length) and finish: black (bare), pre-galvanized or hot-dip galvanized.