This standard stipulates the standard dimensions of large-diameter low-pressure steel flasks (hereinafter referred to as flasks) with a nominal diameter of 550 mm or more used for marine exhaust gas pipes, flues, etc.
JIS F 7805:1976 history
2013JIS F 7805:2013 Ships and marine technology.Marine steel pipe flanges for exhaust gas pipe
1976JIS F 7805:1976 Basic dimensions of steel flanges for marine exhaust gas pipe