| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a steam valve applicable to high-pressure and high-temperature steam, because a cast material conventionally used for a valve casing does not have sufficient strength against an increase in load and a decrease in allowable load which results from effects of the high-pressure and high-temperature steam on a valve's screw hole part, thus making it difficult for the conventional cast material to be used for the steam valve. Ž<P>SOLUTION: A steam valve 90 includes: a valve casing 11 that houses therein a valve-housed component; and a top cover 12 that closes an upper opening 91 of the valve casing 11 with an upper cover attachment bolt 20. The valve casing 11 is manufactured by screwing the upper cover attachment bolt 20 thereinto and welding a screw part valve casing 11a produced from a forged material and a lower valve casing 11b produced from a cast material. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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