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

---
identifier: "/us/cfr/t46/s153.470"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "46 CFR § 153.470 - System for discharge of NLS residue to the sea: Categories A, B, C, and D."
title_number: 46
title_name: "Shipping"
section_number: "153.470"
section_name: "System for discharge of NLS residue to the sea: Categories A, B, C, and D."
chapter_name: "COAST GUARD, DEPARTMENT OF HOMELAND SECURITY"
subchapter_number: "O"
subchapter_name: "CERTAIN BULK DANGEROUS CARGOES"
part_number: "153"
part_name: "SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "46 U.S.C. 3703; Department of Homeland Security Delegation No. 0170.1. Section 153.40 issued under 49 U.S.C. 5103. Sections 153.470 through 153.491, 153.1100 through 153.1132, and 153.1600 through 153.1608 also issued under 33 U.S.C. 1903 (b)."
regulatory_source: "CGD 73-96, 42 FR 49027, Sept. 26, 1977, unless otherwise noted."
cfr_part: "153"
---


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

Unless waived under § 153.491, 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 and 153.1128 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:

where:

D = Minimum diameter of the discharge outlet in meters.

Q<sub>d</sub> = Maximum rate in cubic meters per hour at which the ship operator wishes to discharge slops (note: Q<sub>d</sub> affects the discharge rate allowed under § 153.1126(b)(2)).

L = Distance from the forward perpendicular to the discharge outlet in meters.

φ = The acute angle between a perpendicular to the shell plating at the discharge location and the direction of the average velocity of the discharged liquid.

(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), the NLS residue discharge system must have two outlets located on opposite sides of the ship.

[CGD 81-101, 52 FR 7781, Mar. 12, 1987, as amended by CGD 81-101, 53 FR 28974, Aug. 1, 1988 and 54 FR 12629, Mar. 28, 1989; CGD 95-028, 62 FR 51209, Sept. 30, 1997]