| 摘要 |
PROBLEM TO BE SOLVED: To reduce strain of a pressure tank by welding heat and reduction in corrosion resistance by a change in material physical properties caused when welding the pressure tank. SOLUTION: A flange part is constituted to be joined without welding a drum having a spherical ring-shaped upper part for constituting the pressure tank and a spherical ring-shaped bottom plate. A material does not change by dususing welding, so that the corrosion resistance does not reduce. Welding equipment is not required so that an inexpensive well pump can be provided.
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