US Patent 12090352 Fire stop assembly for concrete structures

A concrete structure with a corrugated bottom surface has a pipe passing through a passage in the structure. A fire stop assembly has a first portion with a split plate, split cage, split intumescent ring, split inner smoke ring and split outer smoke ring each fastened together to rotate together about a hinge on the split cage. The fire stop assembly has a second portion of the split plate, split cage, split intumescent ring, split inner smoke ring and split outer smoke ring fastened together to rotate together about a hinge. The first and second portions have free ends that spread apart to fit around the tube in an open position, and close around the tube in a closed position.