(a) A cargo tank must have at least one covered manhole opening into the vapor space described in Sec. 153.354.
(b) An access through a vertical cargo tank surface must be at least 60 cm by 80 cm (approx. 23.6 x 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 x 23.6 in.).
(d) An access trunk must be no less than 76 cm (approx. 29.9 in.) in diameter.