It depends on the application.
have the advantages of low price, light weight, anti-theft, and reduction of urban noise. In terms of anti-corrosion, composite resin manhole covers are high-performance SMC sheet products with acid resistance, alkali resistance, salt corrosion resistance, and no rust. Used in harsh environmental conditions from -50 ° C to 150 ° C. But the carrying capacity is small

Cast iron manhole covers are now nodular cast iron, safe and anti-theft, large carrying capacity, and slightly expensive. The bearing capacity is required to be less than 30 tons, and composite ones can be considered, and more than 30 tons, nodular cast iron must be used.