To efficiently connect a protrusion to a lining sheet with high quality by externally inserting a heat shrinkage tube made of a high density polyethylene to an outer surface of the protrusion with a hot-melt adhesive for a polyethylene, and covering the protrusion with the tube by heat shrinkage in association with adhering.

The treating tank comprises a tubular protrusion 3 protruding from a surface to be anti-corroded of an inner wall surface. The protrusion 3 is covered with a heat shrinkage tube 4 by its heat shrinkage to connect the tube 4 to a lining sheet to cover the surface to be anti-corroded each other. A protrusion part 9A of a pipe 9 from a hole of the sheet is covered with the tube 4 made of a high density polyethylene with a hot-melt adhesive 10 for a polyethylene, and the tube 4 is connected to the hole of the sheet. Since the tube 4 is formed of the same type material as that of the sheet, they can be integrally connected, for example, by a thermal deposition.