49 CFR Part 173 sets the hazardous materials shipping requirements that anyone offering a hazmat package for transport by air, highway, rail, or water in the United States has to meet before a carrier will legally accept it.1eCFR. 49 CFR 173.1 – Purpose and Scope The rules cover classification, packaging, filling, and closure, and they work alongside the marking, labeling, and shipping paper rules in Part 172. Get any step wrong and you are personally exposed to civil penalties that now reach $102,348 per violation, and criminal charges when a shipment causes harm.2Federal Register. Revisions to Civil Penalty Amounts, 2025
Who Is Responsible
The person who offers the material for transport carries the full legal weight. Under 49 CFR 173.22, you must identify the material’s hazard class, choose an authorized packaging, and confirm the container was manufactured and maintained to specification before you hand it to a carrier.3eCFR. 49 CFR 173.22 – Shipper’s Responsibility A carrier can refuse a package that looks wrong, but refusal does not transfer the liability. If the classification was off, the shipper answers for it.
Classifying the Material
Classification puts a substance into one of nine hazard classes, running from explosives in Class 1 through radioactive materials in Class 7 to miscellaneous hazards in Class 9. Many materials fit more than one class. When they do, 49 CFR 173.2a requires you to assign the material to the highest applicable hazard using a fixed precedence order, with radioactive materials at the top, followed by poison gases, flammable gases, and downward from there.4eCFR. 49 CFR 173.2a – Classification of a Material Having More Than One Hazard The wrong hazard assignment produces the wrong labels, the wrong carrier handling, and the wrong emergency response.
Packing Groups
Inside a hazard class, materials are sorted into three packing groups by danger level: Group I for great danger, Group II for medium danger, and Group III for minor danger.5PHMSA. Performance Packaging Codes The packing group sets how tough the container has to be. A Group I flammable liquid demands a stronger container than a Group III one because a failure is far more consequential.
Packaging That Meets the Standard
Every hazmat package must be designed and closed so there is no identifiable release to the environment under normal transport conditions.6eCFR. 49 CFR 173.24 – General Requirements for Packagings and Packages Normal conditions include highway vibration, air pressure changes, temperature swings on a loading dock, and rail switching jolts. The container must handle all of it without meaningful loss of effectiveness.
Packaging also has to be chemically compatible with the contents. Plastic containers can turn brittle or permeable when they sit against certain chemicals, and the regulations require that plastic packaging not allow contents to permeate the walls above set thresholds. Confirming compatibility is the shipper’s job, not the packaging manufacturer’s.
Containers must meet United Nations performance-oriented packaging standards, which involve drop tests and pressure assessments. A container that passes carries a UN marking showing the level it was tested to. Using a container rated below what the material’s packing group requires is a federal violation even if the container looks perfectly intact.
Filling Limits and Closures
Liquids cannot be filled to the top. There has to be enough empty space, sometimes called outage or ullage, that the liquid will not completely fill the receptacle at 55°C (131°F). A drum sealed in a climate-controlled warehouse can fail on a flatbed in August if this is ignored.
Closures matter just as much. Every cap, bung, and lid has to be secured to the manufacturer’s torque specifications. Hand-tight is not torque-wrench-tight, and a closure that vibrates loose in transit takes the package out of “authorized” status. Carriers reject improperly closed packages on inspection.
Overpacks
If you consolidate several hazmat packages into a single outer container, that outer container is an overpack, and it has to display the proper shipping name and identification number for each material inside along with any required labels, unless those markings are visible through the overpack itself.7eCFR. 49 CFR 173.25 – Authorized Packagings and Overpacks When specification packaging is required or the shipment contains radioactive material, the word “OVERPACK” must appear on the outside in letters at least 12 mm (0.5 inches) high. Inner packages that require orientation markings must go in with fill holes up, and the overpack itself needs orientation arrows on two opposite sides.
Marking and Labeling
The marking and labeling rules live in Part 172, but you cannot ship under Part 173 without them. Every non-bulk hazmat package needs the proper shipping name and the identification number preceded by “UN,” “NA,” or “ID” as appropriate. The ID number must appear in characters at least 12 mm high for standard packages, dropping to 6 mm for containers of 30 liters or less.8eCFR. 49 CFR 172.301 – General Marking Requirements for Non-Bulk Packagings
Hazard labels sit alongside the markings. The Hazardous Materials Table in 49 CFR 172.101 tells you which labels apply. They use standardized colors and symbols so the warning carries across languages, and they must stay legible and visible for the entire trip.9eCFR. 49 CFR 172.400 – General Labeling Requirements Strapping or stacking that covers a label defeats it and violates the rule.
Shipping Papers and Certification
Before a carrier accepts your shipment, you have to provide shipping papers that give the proper shipping name, hazard class, identification number, and quantity. The papers must also list an emergency response telephone number monitored at all times the material is in transit, answered by someone knowledgeable about the specific material or with immediate access to someone who is. An answering machine or callback service does not satisfy this.10eCFR. 49 CFR 172.604 – Emergency Response Telephone Number
The shipping paper carries a signed shipper’s certification stating that the materials are properly classified, described, packaged, marked, labeled, and in proper condition for transport.11eCFR. 49 CFR 172.204 – Shipper’s Certification This signature is a legally binding declaration. If any of it is false because a corner got cut, the person who signed is on the hook for the full civil and criminal exposure.
When the Rules Ease Up
Not every hazmat shipment carries the full load of requirements. Part 173 contains exceptions for small volumes where the risk is limited.
Limited Quantity
Limited quantities of materials such as flammable liquids are exempt from labeling (except for air shipments), from specification packaging, and from placarding, provided they are packed in combination packagings that do not exceed 30 kg (66 pounds) gross weight. Inner packaging size depends on the packing group: 0.5 liters for Packing Group I flammable liquids, 1.0 liter for Group II, and 5.0 liters for Group III and combustible liquids.12eCFR. 49 CFR 173.150 – Exceptions for Class 3 Shipping papers are still required for hazardous substances, hazardous wastes, marine pollutants, and any shipment by air or vessel.
Small Quantity
The small quantity exception in 49 CFR 173.4 goes further, covering inner receptacles of no more than 30 mL for liquids or 30 g for solids. For the most dangerous poison-by-inhalation materials (Division 6.1, Packing Group I, Hazard Zones A or B), the limit drops to 1 gram per inner packaging. Qualifying shipments are relieved of most requirements, but the packaging still has to prevent any release under normal transport conditions.
Training Every Hazmat Employee
Anyone who handles, packages, or prepares hazardous materials for shipment must complete training in four areas before doing the work unsupervised:13eCFR. 49 CFR 172.704 – Training Requirements
- General awareness of the regulations and how to recognize hazardous materials from standard hazard communication.
- Function-specific training on the regulatory requirements that apply to that employee’s actual duties.
- Safety training covering emergency response, personal protection, and accident avoidance.
- Security awareness covering the risks in hazmat transport and how to respond to potential threats.
Recurrent training is required at least once every three years.14PHMSA. Hazardous Materials Training Requirements Employers must keep records for each employee showing name, completion date, description or copy of materials, trainer’s name and address, and a certification that the employee was trained and tested. Records stay on file for the duration of the employee’s hazmat work and 90 days after, covering the preceding three years. Training violations carry a mandatory minimum civil penalty of $450.15Office of the Law Revision Counsel. 49 USC 5123 – Civil Penalty
If Something Goes Wrong
When a hazmat incident happens during transportation, including loading, unloading, and temporary storage, the person in physical possession of the material must call the National Response Center at 800-424-8802 as soon as practical, and no later than 12 hours after the incident, whenever any of the following occurs as a direct result of the hazardous material:16eCFR. 49 CFR 171.15 – Immediate Notice of Certain Hazardous Materials Incidents
- A person is killed or requires hospital admission.
- The general public is evacuated for one hour or more.
- A major roadway or facility is shut down for one hour or more, or an aircraft’s flight pattern is altered.
- Any fire, breakage, spillage, or suspected contamination involves radioactive or infectious material.
- More than 119 gallons of liquid or 882 pounds of solid marine pollutant is released.
- A battery or battery-powered device causes fire, explosion, or dangerous heat evolution during air transport.
A written report on DOT Form F 5800.1 follows within 30 days for any incident that triggered a phone report, plus additional situations including any unintentional release and discovery of an undeclared hazmat shipment.17eCFR. 49 CFR 171.16 – Detailed Hazardous Materials Incident Reports
What Violations Cost
The statutory ceiling for a civil penalty is $75,000 per knowing violation, rising to $175,000 when a violation results in death, serious illness, severe injury, or substantial property destruction.15Office of the Law Revision Counsel. 49 USC 5123 – Civil Penalty After inflation adjustments, those figures currently stand at $102,348 and $238,809.2Federal Register. Revisions to Civil Penalty Amounts, 2025 Each day a continuing violation persists is a separate offense, so exposure stacks fast.
Criminal prosecution is reserved for willful or reckless violations. Conviction brings a fine under Title 18 and up to five years in prison, doubling to ten years when a release causes death or bodily injury.18Office of the Law Revision Counsel. 49 USC 5124 – Criminal Penalty Shipping undeclared hazardous materials is among the most aggressively prosecuted offenses in this area because nobody in the handling chain knows what they are touching. A person who fails to pay assessed civil penalties can also be barred from any regulated hazmat activity starting 91 days after the payment deadline.