33 CFR 155.310: Containment of cargo discharges on tank vessels

Last reviewed: October 14, 2026

This section requires certain tank vessels and barges with a capacity of 250 or more barrels to contain cargo discharges on deck. Depending on the vessel, it requires fixed containers or enclosed deck areas, or coamings. Each must have a way to drain or remove spilled cargo without discharging it into the water, and a mechanical means of closing drains and scupper.

Applies toTank vessels, offshore tank barges, inland tank barges, oil tankers and offshore oil barges with a capacity of 250 or more barrels that carry oil or hazardous material as cargo, as described in each paragraph.

What it says

  1. A tank vessel with a capacity of 250 or more barrels that carries oil or hazardous material as cargo must have a fixed container or enclosed deck area under or around each loading manifold and each transfer connection point.

    33 CFR 155.310(a)(1)“Under or around each loading manifold and each transfer connection point, a fixed container or enclosed deck area that, in all conditions of ship list or trim encountered during the loading operation, has a capacity of at least:”

  2. The container or enclosed deck area must hold four barrels if it serves one or more hoses with an inside diameter of 12 inches or more, or loading arms with a nominal pipe size diameter of 12 inches or more.

    33 CFR 155.310(a)(1)(v)“Four barrels if it serves one or more hoses with an inside diameter of 12 inches or more, or one or more loading arms with a nominal pipe size diameter of 12 inches or more;”

  3. The tank vessel must have a means of draining or removing discharged oil or hazardous material from each container or enclosed deck area without discharging it into the water.

    33 CFR 155.310(a)(2)“A means of draining or removing discharged oil or hazardous material from each container or enclosed deck area without discharging the oil or hazardous material into the water; and”

  4. The tank vessel must have a mechanical means of closing each drain and scupper in the container or enclosed deck area.

    33 CFR 155.310(a)(3)“A mechanical means of closing each drain and scupper in the container or enclosed deck area required by this section.”

  5. An offshore tank barge carrying hazardous material and an inland tank barge carrying oil or hazardous material, each with a capacity of 250 or more barrels, must meet paragraph (a) or be equipped with the coaming and related equipment listed in paragraph (b).

    33 CFR 155.310(b)“must meet paragraph (a) of this section or be equipped with—”

  6. All oil tankers and offshore oil barges with a cargo capacity of 250 or more barrels must have peripheral coamings completely enclosing the cargo deck area, cargo hatches, manifolds, transfer connections, and other openings where cargo may overflow or leak.

    33 CFR 155.310(c)“must have peripheral coamings, including port and starboard coamings and forward and aft athwartships coamings, completely enclosing the cargo deck area, cargo hatches, manifolds, transfer connections, and any other openings where cargo may overflow or leak.”

  7. Coamings must be at least 4 inches high except in the aft corners, where they must be at least 8 inches high.

    33 CFR 155.310(c)(1)“Coamings must be at least 4 inches high except in the aft corners.”

  8. An offshore oil barge with a cargo capacity of 250 or more barrels must also have a fixed or portable container holding at least one-half barrel under each oil loading manifold and each oil transfer connection within the coaming.

    33 CFR 155.310(d)(1)“A fixed or portable container that holds at least one-half barrel under each oil loading manifold and each oil transfer connection within the coaming;”

Common questions

How high must coamings be on an oil tanker?

Coamings must be at least 4 inches high except in the aft corners. In the aft corners they must be at least 8 inches high.

“Coamings must be at least 4 inches high except in the aft corners.”

How far must the aft corner coamings extend?

They must extend forward at least 14 feet from each corner and inboard at least 8 feet from each corner.

“In the aft corners (port and starboard) of a vessel, the coamings must be at least 8 inches high and extend—”

Do containment areas need drains that close?

Yes. The tank vessel must have a mechanical means of closing each drain and scupper in the container or enclosed deck area.

“A mechanical means of closing each drain and scupper in the container or enclosed deck area required by this section.”

Can a tankship use another barrier as its aft athwartships coaming?

Yes. For a tankship as defined in 46 CFR 30.10-67, the coaming or other barrier required in 46 CFR 32.56-15 may serve as the aft athwartships coaming if the tankship otherwise complies with this section.

“the coaming or other barrier required in 46 CFR 32.56-15 may serve as the aft athwartships coaming if the tankship is otherwise in compliance with the requirements of this section.”

The text of 33 CFR 155.310

Electronic Code of Federal Regulations (eCFR), current as of April 16, 2026 · Read it on eCFR

Containment of oil and hazardous material cargo discharges

(a) A tank vessel with a capacity of 250 or more barrels that is carrying oil or hazardous material as cargo must have—

(1) Under or around each loading manifold and each transfer connection point, a fixed container or enclosed deck area that, in all conditions of ship list or trim encountered during the loading operation, has a capacity of at least:

(i) One half barrel if it serves one or more hoses with an inside diameter of 2 inches or less, or one or more loading arms with a nominal pipe size diameter of 2 inches or less;

(ii) One barrel if it serves one or more hoses with an inside diameter of more than 2 inches but less than 4 inches, or one or more loading arms with a nominal pipe size diameter of more than 2 inches but less than 4 inches;

(iii) Two barrels if it serves one or more hoses with an inside diameter of 4 inches or more, but less than 6 inches, or one or more loading arms with a nominal pipe size diameter of 4 inches or more, but less than 6 inches;

(iv) Three barrels if it serves one or more hoses with an inside diameter of 6 inches or more, but less than 12 inches, or one or more loading arms with a nominal pipe size diameter of 6 inches or more, but less than 12 inches; or

(v) Four barrels if it serves one or more hoses with an inside diameter of 12 inches or more, or one or more loading arms with a nominal pipe size diameter of 12 inches or more;

(2) A means of draining or removing discharged oil or hazardous material from each container or enclosed deck area without discharging the oil or hazardous material into the water; and

(3) A mechanical means of closing each drain and scupper in the container or enclosed deck area required by this section.

(b) An offshore tank barge with a cargo capacity of 250 or more barrels that is carrying hazardous material as cargo and an inland tank barge with the capacity of 250 or more barrels that is carrying oil or a hazardous material as cargo must meet paragraph (a) of this section or be equipped with—

(1) A coaming, at least 4 inches high but not more than 8 inches high, enclosing the immediate area of the cargo hatches, loading manifolds, and transfer connections, that has a capacity, in all conditions of vessel list and trim to be encountered during the loading operation, of at least one-half barrel per hatch, manifold, and connection within the enclosed area;

(2) A fixed or portable container under each loading manifold and each transfer connection within the coaming, that holds at least one-half barrel;

(3) A mechanical means of closing each drain and scupper within the coaming; and

(4) A means of draining or removing discharged oil or hazardous material from the fixed or portable container and from within the coamings without discharging the oil or hazardous material into the water.

(c) All oil tankers and offshore oil barges with a cargo capacity of 250 or more barrels must have peripheral coamings, including port and starboard coamings and forward and aft athwartships coamings, completely enclosing the cargo deck area, cargo hatches, manifolds, transfer connections, and any other openings where cargo may overflow or leak.

(1) Coamings must be at least 4 inches high except in the aft corners.

(2) In the aft corners (port and starboard) of a vessel, the coamings must be at least 8 inches high and extend—

(i) Forward at least 14 feet from each corner; and

(ii) Inboard at least 8 feet from each corner.

(3) Each area enclosed by the coaming required under this paragraph must have—

(i) A means of draining or removing oil from the enclosed deck area without discharging oil into the water; and

(ii) A mechanical means of closing each drain and scupper in the enclosed deck-area.

(4) For a tankship, as defined in 46 CFR 30.10-67, the coaming or other barrier required in 46 CFR 32.56-15 may serve as the aft athwartships coaming if the tankship is otherwise in compliance with the requirements of this section.

(d) In addition to the requirements of paragraphs (a) and (b) of this section, an offshore oil barge with a cargo capacity of 250 or more barrels must have—

(1) A fixed or portable container that holds at least one-half barrel under each oil loading manifold and each oil transfer connection within the coaming;

(2) A mechanical means of closing each drain and scupper within the coaming; and

(3) A means of draining or removing discharged oil from the fixed or portable container and from within the coaming without discharging the oil into the water.

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.