Light negative ring duct piece convenient and rapid to disassemble

The utility model provides a light negative ring duct piece which is convenient and quick to disassemble. The negative ring duct piece is formed by splicing a top sealing block, two adjacent blocks and three standard blocks, the three standard blocks are spliced to form a lower half ring structure of the negative ring duct piece, and the two adjacent blocks are symmetrically spliced on the two sides of the top sealing block and spliced with the adjacent standard blocks; the top sealing block, the adjacent block and the standard block are each of a semi-closed steel structure defined by steel plates, the outer ring of the semi-closed steel structure is closed, the inner ring of the semi-closed steel structure is hollow, a reinforcing rib plate is arranged in the hollow inner ring of the semi-closed steel structure, and hoisting holes are formed in the top sealing block, the adjacent block and the standard block. The split mounting type negative ring duct piece is light and reliable in structure, adopts a split