DUAL PIPE CAPABLE OF PREVENTING BREAKAGE CAUSED BY FREEZING

摘要

PURPOSE: A dual pipe is provided to absorb the transform of a metal pipe caused by volume expansion of the pipe. CONSTITUTION: A dual pipe includes an inner pipe body(20) made by soft material to guide water flow to a hollow portion of an outer pipe body(10) and to prevent transform of the outer pipe body when the water is frozen or thawed in the pipe body. The inner pipe body has corrugated form to prevent the life span from being shortened by the partial contraction of the pipe and to minimize the occupation of the inner sectional area of the outer pipe body. A gap(G) between the inside of the outer pipe body and the outside of the inner pipe body is preferably 2-5% of the inner sectional area of the outer pipe body in proportion to an expansion rate when the water is frozen in the inner pipe body. If the water is frozen in the dual pipe in winter, volume expansion occurs by phase change into solid from liquid. The inner pipe body is expanded, and the gap gets smaller as much as the expansion transform caused by the frozen water. Therefore, the outer pipe body is not influenced by the frozen water in the inner pipe body. The dual pipe is prevented from being damaged by the frozen water.