Ventilated breathe freely, is not easy to accumulate their booty and corrosion resistance. 1.1 Grating Conformity Standard: YB/T4001, ANSI/NAAMM-MBG531, BS4592, AS1657, JS31011.2 Grating Dimension Load Bearing Flat Bar sizeThickness≥3mm, depth ≥19mm19X3,19X5,20X3, 20X5, 25X3, 25X4, 25X4.5, 25X4.7, 25X5…..40X6, 40X8, 40X10,….90X6….Pitch of Load bearding flat bars(mm)12.5,15, 20, 30, 30.6, 32.5, 34 ...