Cast Iron Pipes, pipes formed by casting iron. Used for water supply, drainage, and gas transmission lines, including cast iron straight pipes and fittings. Low labor intensity. Divided into continuous cast iron pipes and centrifugal cast iron pipes according to casting methods, with centrifugal cast iron pipes further categorized into sand mold and metal mold types. Classified by material into gray iron pipes and ductile iron pipes. And by joint type, into flexible joints, flange joints, self-anchoring joints, rigid joints, etc.