PURPOSE: To facilitate working of an edge part and improve the resistance to corrosion thereof by a method wherein the end part of the finless sheathing tube covering the outer periphery of the heat pipe is sealed by means of a plug structure.

CONSTITUTION: The end part 8 of the finless sheathing tube is fitted into the annular groove 2 of the plug and an inorganic series adhesive 9 is coated in a clearance therebetween to secure both of them. At least one of the surfaces of the cliffs of the annular groove 2 is provided with a taper, therefore, the end of the finless sheathing tube may be fitted into the groove easily even if enamel is dropping or protruding on the end part of the sheathing pipe upon the calcining thereof and the thickness of the end part is being ununiform. The end edge 8 of the sheathing tube 7 and the edge part 11 of a hole 10 for hanging are covered by the plug 6 of anti-corrosive material and the inorganic series adhesive 9 from the outer and inner surfaces thereof, theefore, they are protected without being exposed to corrosive gas.