Section 45.133 - Air pipes(a) Where an air pipe to any tank extends above the freeboard or superstructure deck- (1) The exposed part of the air pipe must be made of steel and of sufficient thickness to avoid breaking from impact of boarding seas.(2) The air pipe must have a permanently attached means of closing its opening; and(3) The height from the deck to any point where water may obtain access below deck must be at least 30 in above the freeboard deck, 24 in above raised quarter decks, and 12 in above other superstructure decks.(b) If the height required in paragraph (a) of this section interferes with working the ship, the Commandant may approve a lower height after considering the closing arrangements.