EXISTING PIPE CUT-OFF METHOD, EXISTING PIPE SLITTING METHOD, PIPING STRUCTURE, AND VALVE INSERTION METHOD FOR INSERTING A VALVE IN A LINE WITHOUT STOPPING PASSAGE OF WATER OR FLUID

摘要

The invention relates to an existing pipe cut-offmethod and slitting method, by which an existing pipe madeof cast iron and steel can be cut off. With a cut-offmethod according to the invention, first, a part of anexisting pipe 1 is enclosed and sealed up by a seal-uphousing 2 in an airtight state, a cutting tool 30 having aplurality of blades 30c is accommodated in thecorresponding seal-up housing in a state the cutting toolis attached to the abovementioned seal-up housing 2. Next,the cutting tool 30 is fed toward the center of theabovementioned existing pipe 1 while slitting the existingpipe 1 by rotating the cutting tool 30 by power of a primemover, and the abovementioned existing pipe 1 is cut offby the cutting tool 30 by turning the abovementionedseal-up housing 2 in the circumferential direction R of theexisting pipe 1.