1.1 This specification covers 4 to 64-in. ductile iron gravity sewer pipe centrifugally cast with push-on joints. This specification may be used for pipe with other types of joints, as may be agreed upon at the time of purchase. This specification covers ductile iron gravity sewer pipe centrifugally cast with push-on joints. This also covers trench load design procedures for both cement-lined pipe and flexible-lined pipe. Maximum depths of cover tables are included for both ty