... Grating is made by Carbon or mild steel of certain sizes through the processing of grooving, cutting, press-welding, and galvalizing. ... The best drainage: Leakage area of 83.3 percent, more than twice of cast iron products. Hot-dip galvanized treatment: Good ... bar pitch38,50,76,100,101.6mm4MaterialQ235,A36,SS3045Surface treatmentBlack, hot dipped galvanising, paint6StandardChina: YB/T 4001.1-2007USA: ...