The Role of Tree Grates
Cast iron manhole covers are manufactured in foundries where scrap steel collected is melted and alloyed. The melt is poured into casts or molds to manufacture the required design and shape of the manhole cover. The design and shape of manhole covers vary as per requirement. To ensure that the molten metal consists of the correct percentage of iron and alloying metals, proper analysis is carried out prior to casting. Bar test specimens of the same molten metal that will be used for the manhole covers are cast and tested for strength and ductility. The test is carried out by placing the bar in a tensiometer that pulls on the bar ends till failure occurs. Tests have showed that cast iron components have higher safety factors than those of ductile iron.