| 摘要 |
PURPOSE:To reduce the deterioration of corrosion circumstance at the welded part of a boiler body to reduce and prevent the generation of leakage due to corrosion by specifying an adhered length between an inner tube and an outer tube as well as an opening angle between them in the ends of both tubes. CONSTITUTION:An inner tube 1, whose upper part is expanded, and an outer tube 2, whose lower part is contracted, are welded by the method of TIG edge welding or seam welding at the upper and lower welded part so as to have the configuration of gap having an adhered length l of 5mm or less and the angle alpha of opening of 15 deg. or more. According to this method, oxygen concentration cell due to the stagnation of hot-water in the gap of welded parts or the concentration of chloride in hot-water may be reduced and gap corrosion, most liable to be generated in hot-water circumstance, may be reduced effectively.
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