Hazardous Materials Table: Columns, Symbols, and Packaging Codes

The hazardous materials table in 49 CFR 172.101 is the federal master list you consult before shipping any dangerous good in the United States. It is a single alphabetical grid of ten columns, and each column tells you something specific: what to call the material, what hazard class it belongs to, what number identifies it, what labels to apply, which packaging sections govern it, how much you can ship by air or rail, and how it must be stowed on a vessel. Read left to right for each entry and the table walks you through classification, marking, packaging, and documentation in the order the regulations expect.¹

How the Table Is Laid Out

You locate a substance by scanning Column 2, which lists proper shipping names alphabetically. Once you have found the entry, the other nine columns describe how that material must move:¹

Column 1: regulatory symbols that modify how the entry applies.
Column 2: the proper shipping name.
Column 3: hazard class or division.
Column 4: four-digit identification number (UN or NA).
Column 5: packing group.
Column 6: hazard warning label codes.
Column 7: alphanumeric special provisions.
Column 8: packaging section references (Part 173).
Column 9: quantity limits for aircraft and passenger rail.
Column 10: vessel stowage locations and handling codes.

The layout is a checklist by design. You cannot skip to packaging without first pinning down identity, class, and packing group, because the packaging section reference in Column 8 only makes sense after you know what the material is. The same sequence controls the way information appears on shipping papers.

Two appendices sit behind the main table. Appendix A lists CERCLA hazardous substances with their reportable quantities. Appendix B lists marine pollutants. If a marine pollutant is not in the main table by name, you ship it under one of two Class 9 generic entries: “Environmentally hazardous substances, liquid, n.o.s.” (UN3082) or “Environmentally hazardous substances, solid, n.o.s.” (UN3077).¹

Column 1: Symbols That Change the Rules

Six symbols can appear in Column 1, and each one modifies the obligations for that entry:¹

A plus sign locks in the shipping name, hazard class, and packing group shown, even if the material does not technically meet the listed hazard class definition.
The letter D marks a shipping name appropriate for domestic transport but not necessarily for international vessel shipment.
The letter I marks a name intended for international transportation.
The letter G means a technical name must be shown in parentheses with the generic shipping name on documents and packages.
The letter A means the material is regulated only when transported by aircraft, unless it is also a hazardous substance or hazardous waste.
The letter W means the material is regulated only when transported by vessel, unless it is also a hazardous substance or hazardous waste.

Watch the A and W symbols. A material flagged “A” that you move by truck is generally outside the hazmat rules for that trip, but if it also qualifies as a hazardous waste, the exemption falls away and full compliance applies regardless of mode.¹

Columns 2 Through 5: Naming and Classifying the Material

Column 2 gives the proper shipping name. Italicized words are descriptive context, not part of the official name. The entry “Carbon dioxide, solid or Dry ice” means you can use either “Carbon dioxide, solid” or “Dry ice” as the proper shipping name.²

Column 3 assigns the hazard class or division number, which identifies the primary risk: flammability, toxicity, corrosiveness, and so on. Column 4 gives the four-digit identification number, prefixed with UN for internationally recognized materials or NA for materials recognized only in the United States and Canada.¹

Column 5 assigns a packing group tied to the degree of danger. Packing Group I means great danger, Group II medium danger, Group III minor danger.³ The packing group drives which containers are approved in Part 173 and how much material can go in one package.

When the Material Is Not Listed by Name

Not every hazardous material has its own line. If a substance is not listed by its technical name, pick the most specific generic or “n.o.s.” (not otherwise specified) description that matches its hazard class and packing group. An unlisted alcohol goes as “Alcohol, n.o.s.” rather than the broader “Flammable liquid, n.o.s.” When a material falls into more than one hazard class, apply the precedence rules in 49 CFR 173.2a to determine which class controls, then choose the corresponding n.o.s. entry.²

How the Identity Appears on Shipping Papers

The four elements from Columns 2 through 5 must go on the shipping paper in a fixed order known as ISHP: Identification number, proper Shipping name, Hazard class, Packing group. Nothing else can sit between those four elements. A correct entry reads: “UN2744, Cyclobutyl chloroformate, 6.1, (8, 3), PG II.” The total quantity and the number and type of packages (for example, “12 drums”) go before or after that block, not inside it.⁴

Column 6: Label Codes

Column 6 tells you which diamond-shaped hazard warning labels to apply to each package. The first code is the primary hazard label. Any codes after it are subsidiary hazard labels that must also appear.¹

The codes map to standard label names. Common examples: 2.1 is Flammable Gas, 3 is Flammable Liquid, 5.1 is Oxidizer, 6.1 is Poison (or Poison Inhalation Hazard for Zone A or B materials), and 8 is Corrosive. A material classified as a combustible liquid requires no label. Labeling errors are among the most common violations inspectors write, so read every code in this column before ordering labels.

Column 7: Special Provisions

Column 7 lists alphanumeric codes that add requirements or grant exceptions beyond the baseline rules for that entry. The full text of each code lives in 49 CFR 172.102. The letter inside the code tells you its scope:⁵

A codes apply only to air transport.
B codes apply only to bulk packaging.
N codes apply only to non-bulk packaging.
R codes apply only to rail.
T and TP codes apply to portable tanks.
W codes apply only to water transport.
Numeric-only codes are multimodal and can apply to any shipping method.

If a code’s letter matches your mode or packaging type, look it up in 172.102 before you finalize the shipment. Skipping this column is how shippers miss single-line requirements that override the general rules elsewhere in Part 173.

Column 8: Packaging Section References

Column 8 has three sub-columns: 8A for packaging exceptions, 8B for non-bulk packaging, and 8C for bulk packaging. Each sub-column holds a number you read as a section reference inside 49 CFR Part 173. A “202” in Column 8B directs you to 49 CFR 173.202 for the approved non-bulk containers.¹ Using a container type that the referenced section does not authorize is a federal violation and can hold or seize the shipment.

Limited Quantity Exceptions

When Column 8A points to 49 CFR 173.156, certain small-volume shipments qualify for reduced requirements known as the limited quantity exception. The standard cap is 30 kg (66 pounds) gross weight per outer package. That cap is waived for unitized shipments in cages, carts, or similar overpacks moved by rail or under exclusive-use motor carrier service between manufacturers, distribution centers, and retail outlets.⁶

For palletized shipments moving by highway or rail between those same facility types, the per-package weight limit drops away when inner packagings meet quantity limits, trays prevent movement inside fiberboard boxes, and the total hazardous material per palletized unit stays at or below 250 kg (550 pounds). Display packs of consumer commodities can go up to 550 kg (1,210 pounds) per palletized unit.⁶

Columns 9 and 10: Air, Rail, and Vessel Limits

Column 9 splits in two. Column 9A sets the maximum net quantity per package for passenger aircraft and passenger rail cars. Column 9B sets the same limit for cargo-only aircraft.¹

Column 10 also splits in two. Column 10A specifies where the material may be stowed on cargo and passenger vessels: on deck for ventilation, under deck for weather protection, or other designated locations. Column 10B carries codes for additional stowage and handling requirements, such as keeping the material away from heat sources or separating it from incompatible cargo.¹

When “Forbidden” Appears

If the word “Forbidden” shows in Column 9A or 9B, the material cannot move by that mode of transport at all.¹ There is no packaging workaround and no quantity below which it becomes acceptable. Check both sub-columns before quoting a customer or booking a lane.

Common Table-Reading Mistakes That Draw Penalties

Civil penalties for knowingly violating any hazmat transportation requirement top out at $102,348 per violation. When the violation results in death, serious illness, severe injury, or substantial property destruction, the ceiling rises to $238,809. Each day a continuing violation lasts counts as a separate offense.⁷

Criminal prosecution is reserved for willful or reckless violations. A conviction can bring up to five years in prison under Title 18, and up to ten years when the violation causes a release that results in death or bodily injury.⁸ Federal investigators verify compliance through terminal inspections, roadside checks, and post-incident reviews, and they cross-reference shipping papers against the hazardous materials table to catch discrepancies. The common failures are all traceable to a column that was misread or skipped:

Picking a broad n.o.s. name when a more specific generic entry exists in Column 2.
Dropping the technical name in parentheses when Column 1 shows a G symbol.
Applying only the primary label and missing the subsidiary label codes in Column 6.
Using a container not authorized by the Part 173 section referenced in Column 8.
Loading a package on a passenger aircraft when Column 9A shows a lower cap or “Forbidden.”
Ignoring a special provision in Column 7 because the code’s meaning was not looked up in 172.102.

Reading every column for every entry, in order, is the compliance discipline the table is built to enforce. The grid does the work if you let it.

1
eCFR. 49 CFR 172.101 – Purpose and Use of the Hazardous Materials Table
2
eCFR. 49 CFR 172.101 – Purpose and Use of the Hazardous Materials Table
3
eCFR. 49 CFR 171.8 – Definitions and Abbreviations
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eCFR. 49 CFR 172.202 – Description of Hazardous Material on Shipping Papers
5
eCFR. 49 CFR 172.102 – Special Provisions
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eCFR. 49 CFR 173.156 – Exceptions for Limited Quantity Materials
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eCFR. 49 CFR 107.329 – Maximum Penalties
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Office of the Law Revision Counsel. 49 USC 5124 – Criminal Penalty