日本工业标准_JIS F7505-2006 Shipbuilding - Spheroidal graphite iron (ductile iron) valves _F 7505 2006 1 ?QUV wFx|j=OH 12 H 1 wFt,nV|R?O?+jq (JMSA)T?|jj?o?F?Mb?VqwZUK?|?j*qw?&o|TGUMh?FpK? wFwU|?V|Z&?w?Z&|;?VxZ&?w;?JZ&tb?DQUK?qt?Ib?TGt|?j*qx|w?Os?V|Z&?w?Z&|;?VxZ&?w;?JZ&t?tmMo|yx?hsM ?t?lo|wFxwFtw? JIS F 7490:1998