... s drawings or samples Material: Ductile iron manhole CoverFeatures:1) Moulding Process: green sand ... Heat treatment / metallurgical micro-structure analysis improves and ensures physical performances (tensile strength, impact strength, ... auto parts, construction and engineering machinery parts, pipe fittings, valve body, fire hydrant, Manhole cover etc. We ... , QT700; HT250, HT300, TH350 Manhole Cover