153.254—Cargo tank access.
(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.).