METHOD OF LIFTING AND LOWERING PIPE STRING FOR MINING, AND PIPE STRING FOR MINING

摘要

PROBLEM TO BE SOLVED: To provide a method of lifting and lowering a pipe string for mining in which any device for supplying high-pressure air is not required, any increase in the tension resistance can be suppressed even when a depth of a water bottom is increased, and exchange and thinning-out of steel pipes can be performed at an arbitrary position, and to provide the pipe string for mining.;SOLUTION: The pipe string 4 for mining is supported by a workboat, and the pipe string 4 for mining is submerged into the sea or allowed to be afloat on the sea surface. The pipe string 4 for mining is formed by connecting a plurality of steel pipes 3, and corrosion-resistant coating 6 is executed on an outer circumferential surface of each steel pipe 3. The specific gravity of the coating 6 is set to be smaller than that of the sea water for obtaining the buoyancy. When the pipe string 4 for mining is submerged into the sea in a substantially vertical direction, the sea water is poured into the pipe string 4 for mining, so that the total specific gravity of the sea water in the pipe string for mining, the pipe string 4 for mining, and the coating 6, is set to be larger than the specific gravity of the sea water. When the pipe string 4 for mining is afloat on the sea, air is poured into the pipe string 4 for mining and substituted for the sea water. Thus, the total specific gravity of air in the pipe string 4 for mining, the pipe string 4 for mining, and the coating 6, is set to be smaller than the specific gravity of the sea water.;COPYRIGHT: (C)2013,JPO&INPIT