PURPOSE: To prevent the generation of arc discharge, the consumption of a heat insulating material and the invasion of seed agent in lining materials by a method wherein sheet type spacers are arranged at dividing parts so as to be in contact with both of neighboring lining materials.

CONSTITUTION: Metallic lining materials 1b are brought into contact with each other by spacers 8b made of a metal. These spacers 8b are arranged so as to blockade dividing parts 6b when it is seen from the side of a flow passage 9 to prevent a heat insulating member from being sucked into the flow passage 9. According to this method, the spacers 8b, made of a metal, connects the lining materials 1b to each other electrically and, therefore, the lining materials 1b are provided with the same potential even when electric power is generated and an electric field is generated. Further, mutual corners of the spacers 8b are connected and, therefore, the concentration of the electric field is rare. Accordingly, arc discharging is reduced and the lining materials will never be melted. On the other hand, the heat insulating member 2 will never be sucked into the flow of gas while seed agent is bothered by the spacers and will never invade into the heat insulating material.