| 摘要 |
PURPOSE:To make possible to weld a valve box to connecting pipes, by forming coupling pipes which are fitted in the upstream opening and downstream opening of the valve box, respectively, with an iron group material having its outer surface formed thereon with an iron-aluminum alloy layer. CONSTITUTION:A valve element 25 is moved up and down in association with the rotation of a valve rod 23, to make into contact with and separate from a valve seat 21 so that a valve 13 is opened and closed. The outer surface sections of connecting pipes 31, 33 are cast into the upstream and downstream ports of a valve box 11. Such a casting wrap of each connecting pipe 31, 33 is formed when the valve box 11 is cast. These connecting pipes 31, 33 are formed of an iron group material having its outer surface formed thereon with an iron-aluminum alloy layer. Such an iron materials is excellent in the close contact ability and is weldable. Thereby the connecting pipes may be welded in such a condition that pipe members 35, 37 are fitted thereto with no gap.
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