HG/T 20615  法兰 LWN 20-300 RFh6RF.5а“Т а’б‘а’б‘а“Т а’б‘а–т€™а“Т а’б‘а’бžа“Т а’б‘аЊвВа“Т а’б‘а’б‘а“Т а’б‘аВв–т€а