NVIC 04-84: Equivalency for unapproved oil-water separators

Last reviewed: October 14, 2026

This Navigation and Vessel Inspection Circular is Coast Guard guidance. It describes how existing oil-water separators installed before reference (a) was published may be determined equivalent to those presently approved. The determination may include plan review, an inspector's examination, and/or operational testing.

Applies toIt applies to existing oil-water separators installed before the publishing of reference (a), which have not received Coast Guard approval, on U.S. flag ships.

What it says

  1. Reference (b) allows equivalency within the intent of MARPOL 73/78 instead of replacing existing oil-water separators with approved separators.

    “Reference (b) allows for equivalency within the intent of MARPOL 73/78 rather than”

  2. The equivalency determination may consist of plan review, examination by a Coast Guard Marine Inspector, and/or operational testing.

    “may consist of plan review, examination of the installed oil-water separator by a Coast Guard Marine Inspector, and/or operational testing.”

  3. A ship owner who wants Coast Guard review of an unapproved oil-water separator on a U.S. flag ship should submit the plans and manuals described in 46 CFR 162.050-5 to Commandant (G-MVI-3).

    NVIC 04-84 a.“Submit the plans and manuals described in 46 CFR 162.050-5 to Commandant (G-MVI-3) for review.”

  4. The Coast Guard will review the submitted documents under 46 CFR 162.050-21 to decide whether the existing separator is at least as effective as that required by MARPOL 73/78.

    NVIC 04-84 a.“The documents forwarded will be reviewed under 46 CFR 162.050-21 to”

  5. If the plans and manuals are acceptable, a Coast Guard Marine Inspector may examine the separator.

    NVIC 04-84 b.“If the plans and manuals are acceptable, the oil-water separator may be examined by a”

  6. The inspector may check that the separator and its associated equipment are installed in accordance with Coast Guard regulation and good marine practice.

    NVIC 04-84 b.(2)“the oil-water separator and its associated equipment are installed in accordance with Coast Guard regulation and good marine practice,”

Common questions

Do existing oil-water separators have to be replaced with approved ones?

Not necessarily. Reference (b) allows equivalency within the intent of MARPOL 73/78 rather than replacement.

“Reference (b) allows for equivalency within the intent of MARPOL 73/78 rather than”

How is an unapproved oil-water separator determined equivalent?

The determination may consist of plan review, examination by a Coast Guard Marine Inspector, and/or operational testing.

“may consist of plan review, examination of the installed oil-water separator by a Coast Guard Marine Inspector, and/or operational testing.”

Where does a ship owner submit plans for an unapproved separator?

The owner should submit the plans and manuals described in 46 CFR 162.050-5 to Commandant (G-MVI-3) for review.

“Submit the plans and manuals described in 46 CFR 162.050-5 to Commandant (G-MVI-3) for review.”

The text of NVIC 04-84

U.S. Coast Guard, NVIC 04-84 (main body; enclosures not shown)

Equivalent Determination for Existing, Installed Oil-Water Separators which have Not Received U.S. Coast Guard Approval

DEPARTMENT OF TRANSPORTATION UNITED STATES COAST GUARD U.S. Coast Guard (G-MVI-3) Washington, DC 20593 Phone: (202) 426-1444 NVIC 4-84 24 APR 1984 NAVIGATION AND VESSEL INSPECTION CIRCULAR No. 4-84 Subj: Equivalent Determination for Existing, Installed Oil-Water Separators Which Have Not Received U. S. Coast Guard Approval. Refs: (a) 46 CFR 162.050 (b) 33 CFR 155 as modified by 48 FR 45715 dtd 6 Oct 83

Equivalent Determination for Existing, Installed Oil-Water Separators which have Not Received U.S. Coast Guard Approval — PURPOSE. Reference (b) allows for equivalency within the intent of MARPOL 73/78 rather than

replacement of existing oil-water separators with approved separators. This Circular describes how existing oil-water separators installed prior to the publishing of reference (a) may be determined equivalent to those presently approved.

Equivalent Determination for Existing, Installed Oil-Water Separators which have Not Received U.S. Coast Guard Approval — ACTION. Determination of these oil-water separators for equivalency may consist of plan review,

examination of the installed oil-water separator by a Coast Guard Marine Inspector, and/or operational testing. A ship owner who desires Coast Guard review of an unapproved oil-water separator on a U.S. flag ship, should take the following action: a. Submit the plans and manuals described in 46 CFR 162.050-5 to Commandant (G-MVI-3) for review. The documents forwarded will be reviewed under 46 CFR 162.050-21 to determine if the existing oil-water separator is at least as effective as that required by MARPOL 73/78. b. If the plans and manuals are acceptable, the oil-water separator may be examined by a Coast Guard Marine Inspector to determine that:

(1) the oil-water separator and its associated equipment are as detailed in the accepted plans and manuals;

(2) the oil-water separator and its associated equipment are installed in accordance with Coast Guard regulation and good marine practice,

(3) The Pitch And Roll Test. In order to show that the oil-water separator can continue to operate at pitch and roll through both axes of up to 22.50, the ship owner may submit an analysis to Commandant (G-b(VI-3) by a registered professional engineer. Non-Standard Distribution: C:e Baltimore (45); Alameda (40); Port Arthur, Honolulu, Seattle (35); Miami, Mobile, Long Beach

(25); Norfolk, Jacksonville, Portland OR (20); Boston, Portland ME, Charleston, Anchorage (15); Cleveland (12); Cincinnati, Louisville, Memphis, Nashville, Paducah, Pittsburgh, St. Louis, Savannah, San Juan, Tampa, Galveston, Buffalo, Chicago, Detroit, Duluth, Milwaukee, San Diego, Juneau, Valdez (10); Providence, Huntington, Wilmington, Corpus Christi, Toledo (5). C:m New Orleans (140); New York (70); Philadelphia (35); Houston (25); St. Ignace (5); Sturgeon Bay

(4). D:l CG Liaison Officer MILSKALIFTCOMD M-65 STRAT MOB, CG LIAISON OPPICER JUSMAGPHIL (1) ZTC-68

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. The regulation text governs. RegKnot is not affiliated with the U.S. Coast Guard.