46 CFR 148.120: Stowage and segregation of incompatible materials
Last reviewed: October 14, 2026
This section requires each material listed in Table 148.10 of this part to be segregated from incompatible materials. It sets rules on handling and residue and defines the segregation terms. Tables 148.120A and 148.120B give the segregation requirements by hazard class.
Applies toEach material listed in Table 148.10 of this part.
What it says
Each material listed in Table 148.10 of this part must be segregated from incompatible materials under Tables 148.120A and 148.120B for its primary or subsidiary hazard class.
46 CFR 148.120(a)(1)“The requirements of Tables 148.120A and 148.120B of this section that pertain to the primary or subsidiary hazard class to which the materials belong.”
Whenever a subsidiary hazard may exist, the most stringent segregation requirement applies.
46 CFR 148.120(a)(1)“Whenever a subsidiary hazard may exist, the most stringent segregation requirement applies; and”
Each material must also meet any specific requirements in Subpart D of this part.
46 CFR 148.120(a)(2)“Any specific requirements in Subpart D of this part.”
Materials that must be separated during stowage must not be handled at the same time.
46 CFR 148.120(b)“Materials that are required to be separated during stowage must not be handled at the same time.”
Any residue from a material must be removed before a material required to be separated from it is loaded.
46 CFR 148.120(b)“Any residue from a material must be removed before a material required to be separated from it is loaded.”
"Separated from" means located in different cargo compartments or holds when stowed under deck.
46 CFR 148.120(c)(1)““Separated from” means located in different cargo compartments or holds when stowed under deck.”
If the intervening decks are not resistant to fire and liquid, only horizontal separation is acceptable for "separated by a complete cargo compartment or hold from".
46 CFR 148.120(c)(2)“If the intervening decks are not resistant to fire and liquid, only horizontal separation is acceptable.”
"Separated longitudinally by an intervening complete cargo compartment or hold from" means that vertical separation alone does not meet the requirement.
46 CFR 148.120(c)(3)“means that vertical separation alone does not meet this requirement.”
Common questions
Can materials that must be separated be handled at the same time?
No. Materials that are required to be separated during stowage must not be handled at the same time.
“Materials that are required to be separated during stowage must not be handled at the same time.”
What happens if a material has a subsidiary hazard?
Whenever a subsidiary hazard may exist, the most stringent segregation requirement applies.
“Whenever a subsidiary hazard may exist, the most stringent segregation requirement applies; and”
What does "separated from" mean for under-deck stowage?
It means located in different cargo compartments or holds when stowed under deck. A vertical separation is acceptable as equivalent if the intervening deck is resistant to fire and liquid.
“If the intervening deck is resistant to fire and liquid, a vertical separation, i.e., in different cargo compartments, is acceptable as equivalent to this segregation.”
Must residue be removed before loading a material that must be separated from it?
Yes. Any residue from a material must be removed before a material required to be separated from it is loaded.
“Any residue from a material must be removed before a material required to be separated from it is loaded.”
The text of 46 CFR 148.120
Electronic Code of Federal Regulations (eCFR), current as of April 16, 2026 · Read it on eCFR
Stowage and segregation requirements
(a) Each material listed in Table 148.10 of this part must be segregated from incompatible materials in accordance with—
(1) The requirements of Tables 148.120A and 148.120B of this section that pertain to the primary or subsidiary hazard class to which the materials belong. Whenever a subsidiary hazard may exist, the most stringent segregation requirement applies; and
(2) Any specific requirements in Subpart D of this part.
(b) Materials that are required to be separated during stowage must not be handled at the same time. Any residue from a material must be removed before a material required to be separated from it is loaded.
(c) Definitions and application of segregation terms:
(1) “Separated from” means located in different cargo compartments or holds when stowed under deck. If the intervening deck is resistant to fire and liquid, a vertical separation, i.e., in different cargo compartments, is acceptable as equivalent to this segregation.
(2) “Separated by a complete cargo compartment or hold from” means either a vertical or horizontal separation, for example, by a complete cargo compartment or hold. If the intervening decks are not resistant to fire and liquid, only horizontal separation is acceptable.
(3) “Separated longitudinally by an intervening complete cargo compartment or hold from” means that vertical separation alone does not meet this requirement.
Table 148.120A—Segregation Between Incompatible Bulk Solid Cargoes Bulk solid materials Class 4.1 4.2 4.3 5.1 6.1 7 8 9/PDM Flammable solid 4.1 X Spontaneously combustible material 4.2 2 X Dangerous when wet material 4.3 3 3 X Oxidizer 5.1 3 3 3 X Poisonous material 6.1 X X X 2 X Radioactive material 7 2 2 2 2 2 X Corrosive material 8 2 2 2 2 X X X Miscellaneous hazardous material and potential dangerous material 9/PDM X X X X X 2 X X Numbers and symbols indicate the following terms as defined in § 148.3 of this part: 2—“Separated from”. 3—“Separated by a complete hold or compartment from”. X—No segregation required, except as specified in an applicable section of this subpart or Subpart E of this part.
Table 148.120B—Segregation Between Bulk Solid Cargoes and Incompatible Packaged Cargoes Packaged hazardous material Bulk solid material Class 4.1 4.2 4.3 5.1 6.1 7 8 9/PDM Explosives 1.11.21.5 4 4 4 4 2 2 4 X Explosives 1.31.6 3 3 4 4 2 2 2 X Explosives 1.4 2 2 2 2 X 2 2 X Flammable gas 2.1 2 2 1 2 X 2 2 X Non-flammable compressed gas 2.2 2 2 X X X 2 1 X Poisonous gas 2.3 2 2 X X X 2 1 X Flammable liquid 3 2 2 2 2 X 2 1 X Flammable solid 4.1 X 1 X 1 X 2 1 X Spontaneously combustible material 4.2 1 X 1 2 1 2 1 X Dangerous when wet material 4.3 X 1 X 2 X 2 1 X Oxidizer 5.1 1 2 2 X 1 1 2 X Organic peroxide 5.2 2 2 2 2 1 2 2 X Poisonous material 6.1 X 1 X 1 X X X X Infectious substance 6.2 3 3 2 3 1 3 3 X Radioactive material 7 2 2 2 1 X X 2 X Corrosive material 8 1 1 1 2 X 2 X X Miscellaneous hazardous material 9 X X X X X X X X Numbers and symbols indicate the following terms as defined in § 148
.3 of this part: 1—“Away from”. 2—“Separated from”. 3—“Separated by a complete hold or compartment from”. 4—“Separated longitudinally by an intervening complete compartment or hold from”.
X—No segregation required, except as specified in an applicable section of this subpart or Subpart E of this part.
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. Regulation text current as of April 16, 2026. The regulation text governs. RegKnot is not affiliated with the U.S. Coast Guard.