The Hazardous Materials Table, or HMT, is the backbone of the Hazardous Materials Regulations. Understanding and knowing how to use the HMT is the first step toward compliance.

For each material listed, the 172.101 Hazardous Materials Table identifies each hazard class or specifies that the material is forbidden in transportation. It provides the proper shipping name of the material or directs the user to the preferred proper shipping name. In addition, the HMT specifies or references requirements pertaining to labeling, packaging, quantity limits aboard aircraft, and stowage of hazardous materials aboard vessels.

The Hazardous Materials Table usually referred to as the HMT or the Table, governs the transportation of hazardous  materials by all modes air, water, rail and highway. It is important to use the Hazardous Materials Table correctly.

Column (1)  may contain any one of six symbols: a plus sign(+) or the capital letters "A", "D", "G", "I", and "W".

• The plus (+) sign fixes the proper shipping name, hazard class and packing group listed in Columns 2, 3, and 5, of the HMT. “Fixes” means you may not change the proper shipping name, hazard class, or packing group, even if the materials do not meet that hazard class definition. When the “+” sign is assigned to a proper shipping name in Column 1 of the HMT it means that the material is known to pose a risk to humans. The Associate Administrator for Hazardous Materials Safety may authorize an appropriate alternate proper shipping name and hazard class.

• The letter “A” in Column 1 means that the specific material is only regulated if offered or transported by aircraft, unless the material is a hazardous substance or a hazardous waste. Hazardous substances and/or hazardous wastes are regulated in all modes of transportation. A shipping description entry preceded by the letter “A” may be used to describe a material for other modes provided all applicable requirements are met.

• The letter “D” identifies the proper shipping names, which are appropriate for describing materials for domestic
  transportation but may be inappropriate for international transportation under the provisions of international regulations (e.g., IMO, ICAO). An alternate proper shipping name may be selected when either domestic or international transportation is involved.

• The letter “G” identifies n.o.s. (not otherwise specified) and generic proper shipping names for which one or more technical names of the hazardous material must be entered in parentheses, in association with the basic description.

• The letter “I” identifies proper shipping names, which are appropriate for describing materials in international transportation. An alternate proper shipping name may be selected when only domestic transportation is involved.

• The letter “W” in Column 1 means the specific material is regulated only if offered or transported by vessel, unless the material is a hazardous substance or a hazardous waste. Hazardous substances or hazardous wastes are regulated in all modes of transportation.

Column 3 of the HMT contains a designation of the hazard class or division corresponding to each proper shipping name, or the word “Forbidden”. Forbidden means that the material may not be offered for transportation or transported. This prohibition does not apply if the material is diluted, stabilized, or incorporated in a device, and it is classed in accordance with the definitions in Part 173 of the HMR. When test data or new data indicates a need to modify the “Forbidden” designation, the data must be submitted to the Associate Administrator for Hazardous Materials Safety for approval.

The hazard class of a hazardous material is indicated either by its class (or division) number, its class name, or by the letters “ORM-D”. The table contained in 173.2 lists the class numbers, division numbers, class or division names and those sections of the subchapter, which contain definitions for classifying hazardous materials, including forbidden materials.

When the entry for combustible liquids in Column 3 references Class 3, each reference to a Class 3 material must be modified to read “Combustible liquid” when reclassed in accordance
with 173.150(e) or (f).

Column 4 of the HMT lists the 4digit identification number assigned to each proper shipping name. These 4digit numbers provide quick identification of all hazardous materials. It is critical to emergency responders that the numbers are accurate and that they are correctly written and legibly displayed.

Identification numbers preceded by “UN” for United Nations are descriptions of materials for domestic and/or international shipments, while identification numbers preceded by “NA” for North  America may be used to describe certain materials when transported within the United States or between the United States and Canada.

Column 5 of the HMT specifies one or more packing groups assigned to a hazardous material. If a material is assigned to more than one packing group, the shipper must determine the correct packing group for the hazardous material. The packing group of the hazardous material will have an effect on a material’s packaging requirements. This grouping is according to the relative degree of danger presented by the hazardous material. Packing Group One indicates the greatest danger, while Packing Group Two indicates a medium level of danger, and Packing Group Three indicates a minor level of danger.

The packing group number must be indicated in Roman numerals on shipping papers, when applicable, and may be preceded by the letters “PG.” There are no packing groups for Class 2, Class 7, Division 6.2, and ORMD materials.

On shipping papers, the hazardous material must be accurately described and identified in the proper sequence with the proper shipping name ( including the technical name, when
applicable), the hazard class or division, the ID number, the packing group (when applicable); and the total quantity. All shipping papers must describe the hazardous materials in this sequence: the proper shipping name, the hazard class or division, the ID number, the packing group, and the total quantity. These five items make-up the basic description.

Column 6 of the HMT specifies label codes, which represent the hazard warning labels required to be applied to each package of hazardous material, unless excepted. If two label codes are listed, the first represents the primary hazard and the second represents the subsidiary hazard. Additional labeling requirements are found in 172.402.

Column 7 of the HMT specifies codes for special provisions applicable to packaging, packaging requirements, certification, and marking or labeling for a hazardous material. These special provisions are in addition to the standard packaging requirements.

Column 8 of the HMT specifies the applicable sections for packaging authorizations. Notice that Column 8 is divided into three parts - Column 8A, 8B and 8C. The sections cited under Columns 8A, 8B, or 8C are found in Part 173.For example: the number “211” in column 8B indicates that the specific nonbulk packaging requirements are found in 173.211. Also, the number “242” in Column 8C indicates that the specific bulk packaging  requirements are found in 173.242.

When the packaging reference is not applicable to the form (solid or liquid) of the material being transported, use the Solid/Liquid Table in 172.101(i)(4) to determine the correct packaging.

Column 9 is divided into two columns and prescribes the maximum quantity limits for hazardous material transported in one package by either a passenger carrying aircraft or rail car, or by a cargo aircraft only.