# 2.1 — Hazmat load segregation — which hazard classes may travel together, highway vs vessel

For 2.1, second hazard class (table column) is 1.4, 1.6; row description is Flammable gases; transport mode is Carriage by Vessel; segregation code is 2; what the code requires is 2—“Separated from.”, verified against its source on 2026-08-10.

- **First hazard class (table row):** 2.1 _(verified: appears in the quote below)_
- **Second hazard class (table column):** 1.4, 1.6 _(verified: appears in the quote below)_
- **Row description:** Flammable gases _(verified: appears in the quote below)_
- **Transport mode:** Carriage by Vessel _(verified: appears in the quote below)_
- **Segregation code:** 2 _(verified: appears in the quote below)_
- **What the code requires:** 2—“Separated from.” _(verified: appears in the quote below)_

## What the source says

> General Segregation Requirements for Hazardous Materials [Segregation must also take account of a single secondary hazard label, as required by <https://www.ecfr.gov/current/title-49/section-176.83#p-176.83(a)(6)> paragraph (a)(6) of this section.] Class | 1.1, 1.2, 1.5 | 1.3 | 1.4, 1.6 | 2.1 | 2.2 | 2.3 | 3 | 4.1 | 4.2 | 4.3 | 5.1 | 5.2 | 6.1 | 6.2 | 7 | 8 | 9 | Explosives, 1.1, 1.2, 1.5 | (*) | (*) | (*) | 4 | 2 | 2 | 4 | 4 | 4 | 4 | 4 | 4 | 2 | 4 | 2 | 4 | X | Explosives, 1.3 | (*) | (*) | (*) | 4 | 2 | 2 | 4 | 3 | 3 | 4 | 4 | 4 | 2 | 4 | 2 | 2 | X | Explosives, 1.4, 1.6 | (*) | (*) | (*) | 2 | 1 | 1 | 2 | 2 | 2 | 2 | 2 | 2 | X | 4 | 2 | 2 | X | Flammable gases 2.1 | 4 | 4 | 2 | X | X | X | 2 | 1 | 2 | 2 | 2 | 2 | X | 4 | 2 | 1 | X | Non-toxic, non-flammable gases 2.2 | 2 | 2 | 1 | X | X | X | 1 | X | 1 | X | X | 1 | X | 2 | 1 | X | X | Poisonous gases 2.3 | 2 | 2 | 1 | X | X | X | 2 | X | 2 | X | X | 2 | X | 2 | 1 | X | X | Flammable liquids 3 | 4 | 4 | 2 | 2 | 1 | 2 | X | X | 2 | 2 | 2 | 2 | X | 3 | 2 | X | X | Flammable solids 4.1 | 4 | 3 | 2 | 1 | X | X | X | X | 1 | X | 1 | 2 | X | 3 | 2 | 1 | X | Spontaneously combustible substances 4.2 | 4 | 3 | 2 | 2 | 1 | 2 | 2 | 1 | X | 1 | 2 | 2 | 1 | 3 | 2 | 1 | X | Substances which are dangerous when wet 4.3 | 4 | 4 | 2 | 2 | X | X | 2 | X | 1 | X | 2 | 2 | X | 2 | 2 | 1 | X | Oxidizing substances 5.1 | 4 | 4 | 2 | 2 | X | X | 2 | 1 | 2 | 2 | X | 2 | 1 | 3 | 1 | 2 | X | Organic peroxides 5.2 | 4 | 4 | 2 | 2 | 1 | 2 | 2 | 2 | 2 | 2 | 2 | X | 1 | 3 | 2 | 2 | X | Poisons 6.1 | 2 | 2 | X | X | X | X | X | X | 1 | X | 1 | 1 | X | 1 | X | X | X | Infectious substances 6.2 | 4 | 4 | 4 | 4 | 2 | 2 | 3 | 3 | 3 | 2 | 3 | 3 | 1 | X | 3 | 3 | X | Radioactive materials 7 | 2 | 2 | 2 | 2 | 1 | 1 | 2 | 2 | 2 | 2 | 1 | 2 | X | 3 | X | 2 | X | Corrosives 8 | 4 | 2 | 2 | 1 | X | X | X | 1 | 1 | 1 | 2 | 2 | X | 3 | 2 | X | X | Miscellaneous dangerous substances 9 | X | X | X | X | X | X | X | X | X | X | X | X | X | X | X | X | X | Numbers and symbols relate to the following terms as defined in this section: | 1—“Away from.” | 2—“Separated from.” | 3—“Separated by a complete compartment or hold from.” | 4—“Separated longitudinally by an intervening complete compartment or hold from.” | X—The segregation, if any, is shown in the <https://www.ecfr.gov/current/title-49/section-172.101> § 172.101 table. | *—See <https://www.ecfr.gov/current/title-49/part-176/section-176.144> § 176.144 of this part for segregation within Class 1. |

## Source

- https://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/subchapter-C/part-176/subpart-D/section-176.83

Last verified: 2026-08-10. Review by: 2027-08-10.
Part of [Hazmat load segregation — which hazard classes may travel together, highway vs vessel](https://referencesource.org/hazmat-segregation-matrix/).