| 摘要 |
PROBLEM TO BE SOLVED: To eliminate occurrence of a tank crack or a water leakage at a periphery of a heater mounting hole even in the case of a negative pressure in the tank by insert molding a circular patch integrally molded with the same material as a blow molding material at a flange hardware on a periphery of a heater mounting hole at the time of blow molding the tank. SOLUTION: A tank 1 for a water heater is integrally molded by blow molding, and a heater mounting hole 2 for mounting a heater such as a sheathed heater or the like in the tank 1 is provided in addition to a water supply port, a drain port and the like. At the time of molding the tank 1, a circular patch 11 integrally molded wit the same material as the tank 1 is insert molded at a circular flange hardware 10 of a side port adapter member 9 for holding a heater weight in the tank 1 at a periphery of the hole 2. The patch 11 is heat fusion bonded to the tank 1 to hold an adhesive force, and formed in an elliptical shape gradually reduced toward an outer periphery from an inner periphery. Thus, at the time of generating a negative pressure in the tank 1, even when a weight of the heater is operated at the mounting periphery of the heater, a crack or a water leakage can be prevented.
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