46 CFR § 172.240 - Permeability of spaces.
---
identifier: "/us/cfr/t46/s172.240"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "46 CFR § 172.240 - Permeability of spaces."
title_number: 46
title_name: "Shipping"
section_number: "172.240"
section_name: "Permeability of spaces."
chapter_name: "COAST GUARD, DEPARTMENT OF HOMELAND SECURITY"
subchapter_number: "S"
subchapter_name: "SUBDIVISION AND STABILITY"
part_number: "172"
part_name: "SPECIAL RULES PERTAINING TO BULK CARGOES"
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. 3306, 3703, 5115; E.O. 12234, 45 FR 58801, 3 CFR, 1980 Comp., p. 277; DHS Delegation 00170.1, Revision No. 01.2."
regulatory_source: "CGD 79-023, 48 FR 51040, Nov. 4, 1983, unless otherwise noted."
cfr_part: "172"
---
# 172.240 Permeability of spaces.
When doing the calculations required in § 172.225,
(a) The permeability of a floodable space, other than a machinery or cargo space, must be assumed as listed in Table 172.240;
(b) Calculations in which a machinery space is treated as a floodable space must be based on an assumed machinery space permeability of 85% unless the use of an assumed permeability of less than 85% is justified in detail; and
(c) Calculations in which a cargo space that is completely filled is considered flooded must be based on an assumed cargo space permeability of 60% unless the use of an assumed permeability of less than 60% is justified in detail. If the cargo space is not completely filled, a cargo space permeability of 95% must be assumed unless the use of an assumed permeability of less than 95% is justified in detail.
Table 172.240—Permeability
| Spaces and tanks | Permeability (percent) |
| --- | --- |
| Storeroom spaces | 60 |
| Accommodations spaces | 95 |
| Voids | 95 |
| Consumable liquid tanks | 95 or 0 |
| Other liquid tanks | 95 or 0 |
| Cargo (completely filled) | 60 |
| Cargo (empty) | 95 |
| Machinery | 85 |
| Whichever results in the more disabling condition. | |
| If tanks are partially filled, the permeability must be determined from the actual density and amount of liquid carried. | |