---
kind: "range"
citation: "46 C.F.R. §§ 153.470–153.488"
title: "46"
from: "153.470"
to: "153.488"
count: 8
url: "https://uscodex.org/cfr/46/153.470..153.488"
---

# §153.470. System for discharge of NLS residue to the sea: Categories A, B, C, and D.


Unless waived under [§ 153.491](/cfr/46/153.491.md), each ship that discharges Category A, B, or C NLS residue, or Category D NLS residue not diluted to 1/10th of its original concentration, into the sea under §§ [153.1126](/cfr/46/153.1126.md) and [153.1128](/cfr/46/153.1128.md) must have an NLS residue discharge system meeting the following:

- (a) **Minimum diameter of an NLS residue discharge outlet.** The outlet of each NLS residue discharge system must have a diameter at least as great as that given by the following formula:
- (b) **Location of an NLS residue discharge outlet.** Each NLS residue discharge outlet must be located—
  - (1) At the turn of the bilge beneath the cargo area; and
  - (2) Where the discharge from the outlet is not drawn into the ship's seawater intakes.
- (c) **Location of dual NLS residue discharge outlets.** If the value of 6.45 for K is used in [§ 153.1126(b)(2)](/cfr/46/153.1126.md?p=b-2), the NLS residue discharge system must have two outlets located on opposite sides of the ship.

# §153.480. Stripping quantity for Category B and C NLS tanks on ships built after June 30, 1986: Categories B and C.


Unless waived under [§ 153.491](/cfr/46/153.491.md), Category B and C NLS cargo tanks on each ship built after June 30, 1986 must have stripping quantities determined under [§ 153.1604](/cfr/46/153.1604.md) that are less than—

- (a) 0.15 m 3 if Category B; and
- (b) 0.35 m 3 if Category C.

# §153.481. Stripping quantities and interim standards for Category B NLS tanks on ships built before July 1, 1986: Category B.


Unless waived under [§ 153.483](/cfr/46/153.483.md) or [§ 153.491](/cfr/46/153.491.md), each Category B NLS cargo tank on ships built before July 1, 1986 must meet the following:

- (a) Unless the tank meets the interim standard provided by [paragraph (b)](#b) of this section and is prewashed in accordance with [§ 153.1118](/cfr/46/153.1118.md), the tank must have a stripping quantity determined under [§ 153.1604](/cfr/46/153.1604.md) that is less than 0.35m 3.
- (b) Before October 3, 1994, the tank may have a total NLS residue determined under [§ 153.1608](/cfr/46/153.1608.md) that is less than 1.0 m 3 or 1/3000th of the tank's capacity and an NLS residue discharge system meeting the following:
  - (1) The system must be capable of discharging at a rate equal to or less than Q in the following formula:
  - (2) The system must have equipment capable of automatically recording—
    - (i) The time of day that discharge of NLS residue through the residue discharge system starts and ends; and
    - (ii) The dates on which discharge begins and ends unless the equipment allows a person to enter these dates on the record manually.
  - (3) Each system that has the capacity to exceed Q calculated in [paragraph (b)(1)](#b-1) of this section must have equipment that—
    - (i) Records the NLS residue flow through the system; and
    - (ii) Is sufficiently accurate that its recorded values averaged over any 30 second period differ no more than 15% from the actual flow averaged over the same 30 second period.
  - (4) Each system that has the capacity to exceed Q calculated under [paragraph (b)(1)](#b-1) of this section and does not automatically control the flow rate must have—
    - (i) Manual controls that enable the flow to be adjusted to the value of Q calculated in [paragraph (b)(1)](#b-1) of this section and that must be moved through at least 25% of their total range of movement for the discharge rate to change from 0.5Q to 1.5Q; and
    - (ii) **A flow rate meter located where the flow is manually controlled.**

# §153.482. Stripping quantities and interim standards for Category C NLS tanks on ships built before July 1, 1986: Category C.


Unless waived under [§ 153.483](/cfr/46/153.483.md) or [§ 153.491](/cfr/46/153.491.md), each Category C NLS cargo tank on ships built before July 1, 1986 must meet the following:

- (a) Unless the tank meets the interim standard provided by [paragraph (b)](#b) of this section, the tank must have a stripping quantity determined under 153.1604 that is less than 0.95 m 3.
- (b) Before October 3, 1994, the tank may have a total NLS residue determined under [§ 153.1608](/cfr/46/153.1608.md) that is less than 3.0 m 3 or 1/1000th of the tank's capacity.

# §153.483. Restricted voyage waiver for Category B and C NLS tanks on ships built before July 1, 1986: Category B and C.


At its discretion the Coast Guard waives §§ [153.481](/cfr/46/153.481.md) and [153.482](/cfr/46/153.482.md) under this section and allows a ship to carry Category B and C NLS cargoes between ports or terminals in one or more countries signatory to MARPOL 73/78 if the ship's owner requests a waiver following the procedures in [§ 153.10](/cfr/46/153.10.md) and includes—

- (a) **A written pledge to—**
  - (1) Limit the loading and discharge of Category B and C NLS cargoes in a foreign port to those ports and terminals in countries signatory to MARPOL 73/78 and listed in accordance with [paragraph (b)](#b) of this section; and
  - (2) Prewash the cargo tank as required under [§ 153.1118](/cfr/46/153.1118.md) after each Category B or C NLS is unloaded unless the prewash is allowed to be omitted under [§ 153.1114](/cfr/46/153.1114.md);
- (b) **A list of—**
  - (1) All foreign ports or terminals at which the ship is expected to load or discharge Category B or C NLS cargo, and
  - (2) All foreign ports or terminals at which the ship is expected to discharge Category B or C NLS residue from the tank;
- (c) An estimate of the quantity of NLS residue to be discharged to each foreign port or terminal listed under [paragraph (b)(2)](#b-2) of this section;
- (d) Written statements from the owners of adequate reception facilities in the ports and terminals listed in accordance with [paragraph (b)(2)](#b-2) of this section who have agreed to take NLS residue from the ship, showing the amount of NLS residue each agrees to take; and
- (e) A written attestation from the person in charge of each port or terminal listed in accordance with [paragraph (b)(1)](#b-1) of this section that the administration has determined the port or terminal to have adequate reception facilities for the NLS residue.

# §153.484. Prewash equipment.


Unless the ship operator shows that the prewash equipment specified in this section will be available at discharge or prewash facilities or the equipment is waived under [§ 153.491](/cfr/46/153.491.md), to have its Certificate of Inspection or Certificate of Compliance endorsed to carry a Category A NLS or a Category B or C NLS requiring viscosity or melting point information under § [153.908 (a)](/cfr/46/153.908.md?p=a) and [(b)](/cfr/46/153.908.md?p=b), a ship must have the following:

- (a) For the tanks that carry the NLS, a tank washing system capable of washing all interior tank surfaces except those shielded from the washing system spray by ship's structure, and consisting of a wash water supply system and—
  - (1) A fixed tank washing machine in each tank; or
  - (2) A portable tank washing machine and, if required by the Coast Guard, equipment to move it during washing and when storing.
- (b) Piping, valving, and crossovers needed to arrange the cargo piping so that the wash water passes through the cargo pump and cargo piping during tank washing or discharge of tank wash water.
- (c) If the approved Procedures and Arrangements Manual specifies the hot water prewash required under 153.1108, a means of supplying water to the tank washing machine under [paragraph (a)](#a) of this section at—
  - (1) A temperature of at least 60 °C (140 °F) when it leaves the washing machine; and
  - (2) **The flow rate needed for the washing machine jets to meet paragraph (a) of this section.**

# §153.486. Design and equipment for removing NLS residue by ventilation: Categories A, B, C, and D.

- (a) If NLS residue is to be removed from a cargo tank by ventilation, in addition to the equipment required under [paragraph (b)](#b) of this section the ship must have—
  - (1) Openings in the tank deck near the sump or suction point;
  - (2) If the openings required by [paragraph (a)(1)](#a-1) of this section are insufficient, an access opening for visually determining whether liquid remains in the sump area of the cargo tank after ventilation or some other means for making this determination; and
  - (3) An approved Procedures and Arrangements Manual with instructions that meet [§ 153.490(b)(3)](/cfr/46/153.490.md?p=b-3).
- (b) Unless the ship operator shows that the ventilation equipment specified in this paragraph will be available from shore when needed, if NLS residue is to be removed from a cargo tank by ventilation, in addition to the equipment required under [paragraph (a)](#a) of this section the ship must have—
  - (1) Portable forced air ventilating equipment fitting the ventilation openings required in [paragraph (a)](#a) of this section and able to ventilate the extremities of the tank to the extent prescribed in Appendix C of the IMO Standards for Procedures and Arrangements for the Discharge of Noxious Liquid Substances, Resolution MEPC 18(22), 1985; and
  - (2) A connector that allows a fan or air supply to be connected to the hose connections for the tank at the manifold.

# §153.488. Design and equipment for tanks carrying high melting point NLSs: Category B.


Unless waived under [§ 153.491](/cfr/46/153.491.md), for a ship to have its Certificate of Inspection or Certificate of Compliance endorsed allowing a tank to carry a Category B NLS with a melting point of 15 °C or more, the cargo tank must have—

- (a) An arrangement enabling the cargo to be heated before cargo transfer, using heat supplied by the ship or by another source; and
- (b) **Sides and bottom separate from the ship's side or bottom shell plating.**