NB/T 47023  法兰 FM 1000-2.5 а Т а’Т а а†аЂт€“аЂаˆа Т а’Т а бžа вЖа Т а’Т а а†аЂт€“аВв–вЃа Т а вЖа бžаВв–т€œа бžа’ТЗа Т а’Т