... ,40,60mm 3.ISO9001:2000 4.Type T1- Non galvanized stair tread: 1)Material: There are mill steel black, hot dip ... stainless steel grating. 2)Usage: platform, flooring walkway,steel structures, stair tread, well cover, trench cover, sump cover,compound gratings, storage ... , oil project, seaport, power plant, water plant, defense project, chemical factory and so on. 3)Types: Plain Style Steel Grating ...