Ductile iron manhole covers are mainly composed ofDuctile IronThe cast covers we produce; the quality of these covers is crucial.Spheroidization rateThe problem. Common paint used for treating castings is rust preventive.Asphalt PaintCertainly, the surface of the ductile iron manhole cover is also treated with anti-rust asphalt paint. A benefit of the ductile iron manhole cover is that its high strength and good toughness, due to the spheroidal graphite iron, make it...Manhole CoverBe superior to the same typeGray Cast IronManhole covers weigh approximately 30% lighter.