33 CFR 155.815: Closing tank openings on tank vessels
Last reviewed: October 14, 2026
This section requires a tank vessel underway or at anchor to keep closure mechanisms on certain openings properly closed. It limits opening them to when a licensed or credentialed officer or the required tankerman authorizes and supervises it.
Applies toIt applies to a tank vessel that is underway or at anchor.
What it says
Except as paragraph (b) allows, a tank vessel underway or at anchor must have all closure mechanisms properly closed on expansion trunk hatches, ullage openings, sounding ports, tank cleaning openings, and certain other openings.
33 CFR 155.815(a)“a tank vessel underway or at anchor must have all closure mechanisms on the following openings properly closed:”
The openings that must stay closed also include any other tank vessel openings that maintain the seaworthy condition of the tank vessel and prevent the inadvertent release of oil or hazardous material in the event of a tank vessel accident.
33 CFR 155.815(a)(5)“Any other tank vessel openings that maintain the seaworthy condition of the tank vessel and prevent the inadvertent release of oil or hazardous material in the event of a tank vessel accident.”
No person may open these closure mechanisms while the tank vessel is underway or at anchor, except when a licensed or credentialed officer or the tankerman required by 46 CFR 31.15-5(a) authorizes and supervises it.
33 CFR 155.815(b)“No person may open any of the closure mechanisms in paragraph (a) of this section while the tank vessel is underway or at anchor except when authorized and supervised by a licensed or credentialed officer or the tankerman required by 46 CFR 31.15-5(a).”
Common questions
Can tank hatches and sounding ports be opened while underway?
No person may open them while the tank vessel is underway or at anchor, except when authorized and supervised by a licensed or credentialed officer or the tankerman required by 46 CFR 31.15-5(a).
“except when authorized and supervised by a licensed or credentialed officer or the tankerman required by 46 CFR 31.15-5(a).”
Which tank openings must be kept closed?
Expansion trunk hatches, ullage openings, sounding ports, tank cleaning openings, and any other tank vessel openings that maintain seaworthiness and prevent inadvertent release of oil or hazardous material must have their closure mechanisms properly closed.
“Any other tank vessel openings that maintain the seaworthy condition of the tank vessel and prevent the inadvertent release of oil or hazardous material in the event of a tank vessel accident.”
The text of 33 CFR 155.815
Electronic Code of Federal Regulations (eCFR), current as of April 16, 2026 · Read it on eCFR
Tank vessel integrity
(a) Except as provided in paragraph (b) of this section, a tank vessel underway or at anchor must have all closure mechanisms on the following openings properly closed:
(1) Expansion trunk hatches;
(2) Ullage openings;
(3) Sounding ports;
(4) Tank cleaning openings; and
(5) Any other tank vessel openings that maintain the seaworthy condition of the tank vessel and prevent the inadvertent release of oil or hazardous material in the event of a tank vessel accident.
(b) No person may open any of the closure mechanisms in paragraph (a) of this section while the tank vessel is underway or at anchor except when authorized and supervised by a licensed or credentialed officer or the tankerman required by 46 CFR 31.15-5(a).
Sections it refers to
The plain-English explanation on this page was written with AI from the regulation text above and checked automatically before publishing: every quote appears in the text, every number comes from it, and a second model confirmed each statement adds nothing the text doesn't say. Regulation text current as of April 16, 2026. The regulation text governs. RegKnot is not affiliated with the U.S. Coast Guard.