... (4)durable in use HDG steel grid/steel grating for ditch1.Comprehensive type and broadest range in dimension.1. ... ANSI/NAAMM-MBG531, BS4592, AS1657, JS31011.3 Grating Dimension Load Bearing Flat Bar sizeThickness≥3mm, depth ≥19mm19X3,19X5,20X3, ... 25X4.7, 25X5…..40X6, 40X8, 40X10,….90X6….Pitch of Load bearding flat bars(mm)12.5,15, 20, 30, ... square twisted type. HDG steel grid/steel grating for ditch