Septic tank, etc is rotation molded in polyethylene and has vertical ribs on sides and horizontal hollow belt

摘要

A large rotation molded polyethylene tank has two ends (30), vertical ribs (12) on its sides (10) and a horizontal hollow belt (11). The belt is separate from the bottom (16) of the ribs and connects the outermost parts (14) of the ribs to hold them in place. An Independent claim is included for the following: (a) Rotation molding of a hollow ribbed article as above uses two half-molds that fit together at the level of the belt.