46 C.F.R. § 153.254 Cargo tank access.
Title 46 - Shipping
(a) A cargo tank must have at least one covered manhole opening into the vapor space described in §153.354. (b) An access through a vertical cargo tank surface must be at least 60 cm by 80 cm (approx. 23.6 × 31.5 in.) and no more than 60 cm above a foothold grating, or surface on both sides of the access way. (c) An access through a horizontal cargo tank surface must be at least 60 cm by 60 cm (approx. 23.6 × 23.6 in.). (d) An access trunk must be no less than 76 cm (approx. 29.9 in.) in diameter.
Title 46: Shipping
PART 153—SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS
Subpart B—Design and Equipment
Cargo Tanks
§ 153.254 Cargo tank access.
