我和5楼的意思是一样的,请参看ABS 2010 3-2-17/9.3.1
9.3.1 Construction of Coamings (2002)
Ventilators on exposed freeboard or superstructure decks to spaces below the freeboard deck or
decks of enclosed superstructures are to have coamings of steel or other equivalent material.
Coaming-plate thickness is not to be less than 7.5 mm (0.30 in.) for ventilators up to 200 mm (8 in.)
in diameter, and 10 mm (0.40 in.) for diameters of 457 mm (18 in.) and above; the thicknesses for
intermediate diameters may be obtained by interpolation.