hot-dip galvanized steel grating material: Q235,Q255,Q305,Q405,etc. ... 83.3 percent, more than twice of cast iron products. Hot-dip galvanized treatment: Good rust-proof property, maintenance-free replacement ... : ANSI/NAAMM(MBG531-88)UK: BS4592-1987Australia: AS1657-1985 23)HOT SELL!hot dipped galvanized steel grating manufacturer (10 years )