... , ANSI/NAAMM-MBG531, BS4592, AS1657, JS31011.3 Grating Dimension Load Bearing Flat Bar sizeThickness≥3mm, depth ≥19mm19X3,19X5,20X3, 20X5, 25X3, 25X4 ... Plain I type, Serratd type, Serrated I type; Cross bar: Square twisted cross bar, Round cross bar2. Types of Drainage/Ditch Cover ... : a. Normal type; b. U type; c. Security type (anti- ...