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49 CFR 172.423 - DANGEROUS WHEN WET label. | Regulus

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49 CFR Part 172

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titleTitle 49 — Transportation subtitleSubtitle B — Other Regulations Relating to Transportation chapterChapter I — Pipeline and Hazardous Materials Safety Administration, Department of Transportation subchapterSubchapter C — Hazardous Materials Regulations partPart 172 subpartSubpart E—Labeling

33 sections

Subpart A—General2

§ 172.1Purpose and scope.§ 172.3Applicability.

Subpart B—Table of Hazardous Materials and Special Provisions2

§ 172.101Purpose and use of the hazardous materials table.§ 172.102Special provisions.

Subpart C—Shipping Papers6

§ 172.200Applicability.§ 172.201Preparation and retention of shipping papers.§ 172.202Description of hazardous material on shipping papers.§ 172.203Additional description requirements.§ 172.204Shipper's certification.§ 172.205Hazardous waste manifest.

Subpart D—Marking27

§ 172.300Applicability.§ 172.301General marking requirements for non-bulk packagings.§ 172.302General marking requirements for bulk packagings.§ 172.303Prohibited marking.§ 172.304Marking requirements.§ 172.306[Reserved]§ 172.308Authorized abbreviations.§ 172.310Class 7 (radioactive) materials.§ 172.312Liquid hazardous materials in non-bulk packagings.§ 172.313Poisonous hazardous materials.§ 172.315Limited quantities.§ 172.316[Reserved]§ 172.317KEEP AWAY FROM HEAT handling mark.§ 172.320Explosive hazardous materials.§ 172.322Marine pollutants.§ 172.323Infectious substances.§ 172.324Hazardous substances in non-bulk packagings.§ 172.325Elevated temperature materials.§ 172.326Portable tanks.§ 172.327Petroleum sour crude oil in bulk packaging.§ 172.328Cargo tanks.§ 172.330Tank cars and multi-unit tank car tanks.§ 172.331Bulk packagings other than portable tanks, cargo tanks, tank cars and multi-unit tank car tanks.§ 172.332Identification number markings.§ 172.334Identification numbers; prohibited display.§ 172.336Identification numbers; special provisions.§ 172.338Replacement of identification numbers.

Subpart E—Labeling33

§ 172.400General labeling requirements.§ 172.400aa Exceptions from labeling.§ 172.401Prohibited labeling.§ 172.402Additional labeling requirements.§ 172.403Class 7 (radioactive) material.§ 172.404Labels for mixed and consolidated packaging.§ 172.405Authorized label modifications.§ 172.406Placement of labels.§ 172.407Label specifications.§ 172.411EXPLOSIVE 1.1, 1.2, 1.3, 1.4, 1.5 and 1.6 labels, and EXPLOSIVE Subsidiary label.§ 172.415NON-FLAMMABLE GAS label.§ 172.416POISON GAS label.§ 172.417FLAMMABLE GAS label.§ 172.419FLAMMABLE LIQUID label.§ 172.420FLAMMABLE SOLID label.§ 172.422SPONTANEOUSLY COMBUSTIBLE label.§ 172.423DANGEROUS WHEN WET label.§ 172.426OXIDIZER label.§ 172.427ORGANIC PEROXIDE label.§ 172.429POISON INHALATION HAZARD label.§ 172.430POISON label.§ 172.431[Reserved]§ 172.432INFECTIOUS SUBSTANCE label.§ 172.436RADIOACTIVE WHITE-I label.§ 172.438RADIOACTIVE YELLOW-II label.§ 172.440RADIOACTIVE YELLOW-III label.§ 172.441FISSILE label.§ 172.442CORROSIVE label.§ 172.444[Reserved]§ 172.446CLASS 9 label.§ 172.447LITHIUM BATTERY label.§ 172.448CARGO AIRCRAFT ONLY label.§ 172.450EMPTY label.

Subpart F—Placarding38

§ 172.500Applicability of placarding requirements.§ 172.502Prohibited and permissive placarding.§ 172.503Identification number display on placards.§ 172.504General placarding requirements.§ 172.505Placarding for subsidiary hazards.§ 172.506Providing and affixing placards: Highway.§ 172.507Special placarding provisions: Highway.§ 172.508Placarding and affixing placards: Rail.§ 172.510Special placarding provisions: Rail.§ 172.512Freight containers and aircraft unit load devices.§ 172.514Bulk packagings.§ 172.516Visibility and display of placards.§ 172.519General specifications for placards.§ 172.521DANGEROUS placard.§ 172.522EXPLOSIVES 1.1, EXPLOSIVES 1.2 and EXPLOSIVES 1.3 placards.§ 172.523EXPLOSIVES 1.4 placard.§ 172.524EXPLOSIVES 1.5 placard.§ 172.525EXPLOSIVES 1.6 placard.§ 172.526[Reserved]§ 172.527Background requirements for certain placards.§ 172.528NON-FLAMMABLE GAS placard.§ 172.530OXYGEN placard.§ 172.532FLAMMABLE GAS placard.§ 172.536[Reserved]§ 172.540POISON GAS placard.§ 172.542FLAMMABLE placard.§ 172.544COMBUSTIBLE placard.§ 172.546FLAMMABLE SOLID placard.§ 172.547SPONTANEOUSLY COMBUSTIBLE placard.§ 172.548DANGEROUS WHEN WET placard.§ 172.550OXIDIZER placard.§ 172.552ORGANIC PEROXIDE placard.§ 172.553[Reserved]§ 172.554POISON placard.§ 172.555POISON INHALATION HAZARD placard.§ 172.556RADIOACTIVE placard.§ 172.558CORROSIVE placard.§ 172.560CLASS 9 placard.

Subpart G—Emergency Response Information4

§ 172.600Applicability and general requirements.§ 172.602Emergency response information.§ 172.604Emergency response telephone number.§ 172.606Carrier information contact.

Subpart H—Training4

§ 172.700Purpose and scope.§ 172.701Federal-State relationship.§ 172.702Applicability and responsibility for training and testing.§ 172.704Training requirements.

Subpart I—Safety and Security Plans5

§ 172.800Purpose and applicability.§ 172.802Components of a security plan.§ 172.804Relationship to other Federal requirements.§ 172.820Additional planning requirements for transportation by rail.§ 172.822Limitation on actions by states, local governments, and Indian tribes.

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Subpart A—General2

§ 172.1Purpose and scope.§ 172.3Applicability.

Subpart B—Table of Hazardous Materials and Special Provisions2

§ 172.101Purpose and use of the hazardous materials table.§ 172.102Special provisions.

Subpart C—Shipping Papers6

§ 172.200Applicability.§ 172.201Preparation and retention of shipping papers.§ 172.202Description of hazardous material on shipping papers.§ 172.203Additional description requirements.§ 172.204Shipper's certification.§ 172.205Hazardous waste manifest.

Subpart D—Marking27

§ 172.300Applicability.§ 172.301General marking requirements for non-bulk packagings.§ 172.302General marking requirements for bulk packagings.§ 172.303Prohibited marking.§ 172.304Marking requirements.§ 172.306[Reserved]§ 172.308Authorized abbreviations.§ 172.310Class 7 (radioactive) materials.§ 172.312Liquid hazardous materials in non-bulk packagings.§ 172.313Poisonous hazardous materials.§ 172.315Limited quantities.§ 172.316[Reserved]§ 172.317KEEP AWAY FROM HEAT handling mark.§ 172.320Explosive hazardous materials.§ 172.322Marine pollutants.§ 172.323Infectious substances.§ 172.324Hazardous substances in non-bulk packagings.§ 172.325Elevated temperature materials.§ 172.326Portable tanks.§ 172.327Petroleum sour crude oil in bulk packaging.§ 172.328Cargo tanks.§ 172.330Tank cars and multi-unit tank car tanks.§ 172.331Bulk packagings other than portable tanks, cargo tanks, tank cars and multi-unit tank car tanks.§ 172.332Identification number markings.§ 172.334Identification numbers; prohibited display.§ 172.336Identification numbers; special provisions.§ 172.338Replacement of identification numbers.

Subpart E—Labeling33

§ 172.400General labeling requirements.§ 172.400aa Exceptions from labeling.§ 172.401Prohibited labeling.§ 172.402Additional labeling requirements.§ 172.403Class 7 (radioactive) material.§ 172.404Labels for mixed and consolidated packaging.§ 172.405Authorized label modifications.§ 172.406Placement of labels.§ 172.407Label specifications.§ 172.411EXPLOSIVE 1.1, 1.2, 1.3, 1.4, 1.5 and 1.6 labels, and EXPLOSIVE Subsidiary label.§ 172.415NON-FLAMMABLE GAS label.§ 172.416POISON GAS label.§ 172.417FLAMMABLE GAS label.§ 172.419FLAMMABLE LIQUID label.§ 172.420FLAMMABLE SOLID label.§ 172.422SPONTANEOUSLY COMBUSTIBLE label.§ 172.423DANGEROUS WHEN WET label.§ 172.426OXIDIZER label.§ 172.427ORGANIC PEROXIDE label.§ 172.429POISON INHALATION HAZARD label.§ 172.430POISON label.§ 172.431[Reserved]§ 172.432INFECTIOUS SUBSTANCE label.§ 172.436RADIOACTIVE WHITE-I label.§ 172.438RADIOACTIVE YELLOW-II label.§ 172.440RADIOACTIVE YELLOW-III label.§ 172.441FISSILE label.§ 172.442CORROSIVE label.§ 172.444[Reserved]§ 172.446CLASS 9 label.§ 172.447LITHIUM BATTERY label.§ 172.448CARGO AIRCRAFT ONLY label.§ 172.450EMPTY label.

Subpart F—Placarding38

§ 172.500Applicability of placarding requirements.§ 172.502Prohibited and permissive placarding.§ 172.503Identification number display on placards.§ 172.504General placarding requirements.§ 172.505Placarding for subsidiary hazards.§ 172.506Providing and affixing placards: Highway.§ 172.507Special placarding provisions: Highway.§ 172.508Placarding and affixing placards: Rail.§ 172.510Special placarding provisions: Rail.§ 172.512Freight containers and aircraft unit load devices.§ 172.514Bulk packagings.§ 172.516Visibility and display of placards.§ 172.519General specifications for placards.§ 172.521DANGEROUS placard.§ 172.522EXPLOSIVES 1.1, EXPLOSIVES 1.2 and EXPLOSIVES 1.3 placards.§ 172.523EXPLOSIVES 1.4 placard.§ 172.524EXPLOSIVES 1.5 placard.§ 172.525EXPLOSIVES 1.6 placard.§ 172.526[Reserved]§ 172.527Background requirements for certain placards.§ 172.528NON-FLAMMABLE GAS placard.§ 172.530OXYGEN placard.§ 172.532FLAMMABLE GAS placard.§ 172.536[Reserved]§ 172.540POISON GAS placard.§ 172.542FLAMMABLE placard.§ 172.544COMBUSTIBLE placard.§ 172.546FLAMMABLE SOLID placard.§ 172.547SPONTANEOUSLY COMBUSTIBLE placard.§ 172.548DANGEROUS WHEN WET placard.§ 172.550OXIDIZER placard.§ 172.552ORGANIC PEROXIDE placard.§ 172.553[Reserved]§ 172.554POISON placard.§ 172.555POISON INHALATION HAZARD placard.§ 172.556RADIOACTIVE placard.§ 172.558CORROSIVE placard.§ 172.560CLASS 9 placard.

Subpart G—Emergency Response Information4

§ 172.600Applicability and general requirements.§ 172.602Emergency response information.§ 172.604Emergency response telephone number.§ 172.606Carrier information contact.

Subpart H—Training4

§ 172.700Purpose and scope.§ 172.701Federal-State relationship.§ 172.702Applicability and responsibility for training and testing.§ 172.704Training requirements.

Subpart I—Safety and Security Plans5

§ 172.800Purpose and applicability.§ 172.802Components of a security plan.§ 172.804Relationship to other Federal requirements.§ 172.820Additional planning requirements for transportation by rail.§ 172.822Limitation on actions by states, local governments, and Indian tribes.

Related 5 Definitions History 28 Authority 30

RegulationsTitle 49Subtitle BChapter ISubchapter CPart 172Subpart E—Labeling49 CFR 172.423

Regulationcurrent

49 CFR 172.423

DANGEROUS WHEN WET label.

Current as of 2026-08-18 Government source

eCFR editorial compilationAuthoritative but unofficial

2 passages

(a)Except for size and color, the DANGEROUS WHEN WET label must be as follows:#

(b)In addition to complying with § 172.407, the background color on the DANGEROUS WHEN WET label must be blue.#

Previous§ 172.422 Next§ 172.426

On this page

(a)Except for size and color, the DANGEROUS WHEN WET label must be as follows:(b)In addition to complying with § 172.407, the background color on the DANGEROUS WHEN WET la

Related 5 Definitions History 28 Authority 30 Community

Only explicit, source-backed relationships are shown.

Rulemaking4

87 FR 79752

Hazardous Materials: Editorial Corrections and Clarifications

172.423 · cited in rulemaking

85 FR 83366

Hazardous Materials: Editorial Corrections and Clarifications

172.423 · cited in rulemaking

Improvements to Hazardous Materials Identification Systems

172.423 · cited in rulemaking

Improvements to Hazardous Materials Identification Systems

172.423 · cited in rulemaking

Interpretations & guidance1

Schuster Metals, LLC — Hazardous Materials Safety Interpretation

172.423 · interpreted by

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Record details

Retrieved: Aug 20, 2026
Version: 2026-08-18

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