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46 CFR § 153.1126 - Discharge of NLS residue from a slop tank to the sea: Categories A, B, C, and D. 

---
identifier: "/us/cfr/t46/s153.1126"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "46 CFR § 153.1126 - Discharge of NLS residue from a slop tank to the sea: Categories A, B, C, and D."
title_number: 46
title_name: "Shipping"
section_number: "153.1126"
section_name: "Discharge of NLS residue from a slop tank 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"
---

# 153.1126 Discharge of NLS residue from a slop tank to the sea: Categories A, B, C, and D.

NLS residue in a slop tank may not be discharged into the sea unless—

(a) The ship meets the conditions for discharging the NLS residue from a cargo tank in § 153.1128; and

(b) For Category B NLS residue transferred to the slop tank under § 153.1119(b), the NLS is discharged—

(1) Through an NLS residue discharge system with the flow recording equipment required in § 153.481(b)(2) operating; and

(2) At a rate maintained at or below Q in the following:

For tank contents that are miscible

For tank contents that are immiscible

Q = KU
<sup>1.4</sup> L
<sup>1.6</sup> × 10<sub>−5</sub> m
<sup>3</sup>/hr

where:

Q = maximum permissible slops discharge rate in cubic meters per hour.

V = volume of slops in the tank in cubic meters.

K = 4.3, except K = 6.45 if Q is distributed between two NLS residue discharge outlets on opposite sides of the ship (see §§ 153.470(c) and 153.481(b)).

U = ship's speed in knots.

L = ship's length in meters.

N = number of tanks containing Category B NLS residue pumped into the slop tank.