sand casting manhole cover 1)Grey iron/ductile iron cover 2)process:Sand casting 3)OEM is available 4)shape:around,square Spicification of sanitary sewer manhole cover 1) Material: ductile iron, gray iron, cast steel.2) Standard: BS EN124, BS 497 and according to customer's requirement.3) Surface treatment: Black Bitumen Coated or according to customer's requirement.4) OEM service is available.5) ...