TB 700-2: Ammunition and Explosives Hazard Classification

TB 700-2 is the joint Department of Defense technical bulletin that governs how conventional ammunition and explosives are classified for hazard. Its full designation runs across the services as TB 700-2 / NAVSEAINST 8020.8B / TO 11A-1-47 / DLAR 8220.1.¹ Under TB 700-2, every item gets a hazard division (1.1 through 1.6) and a compatibility group letter, and that combined code determines how far magazines must sit from occupied buildings, which items can share a storage bay, what placards ride on the transport vehicle, and how firefighters should respond if something goes wrong.

The Six Hazard Divisions

All explosives fall under Hazard Class 1. That class is split into six divisions based on the type and severity of hazard each item presents, and the structure aligns with the divisions the Department of Transportation uses in 49 CFR Part 173.²

Division 1.1 covers items with a mass explosion hazard. The entire quantity detonates almost instantaneously. This is the most dangerous category and drives the largest required separation distances.
Division 1.2 covers items with a projection hazard but no mass explosion. Fragments are the primary threat, not a single large blast wave.
Division 1.3 covers fire hazards with minor blast or projection effects and no mass explosion risk. Propellants and large-caliber pyrotechnics typically live here.
Division 1.4 covers minor explosion hazards confined largely to the package, with no significant blast or fragment projection outside the immediate container.
Division 1.5 covers very insensitive substances that carry a mass explosion hazard but have an extremely low probability of initiating or transitioning from burning to detonation under normal transport conditions.
Division 1.6 covers extremely insensitive articles with no mass explosion hazard and a negligible probability of accidental initiation.

The gap between divisions is not academic. A Division 1.1 item triggers full inhabited-building separation distances. A Division 1.4S item, in small quantities, may not require vehicle placarding at all.³

Compatibility Groups

The division is only half the classification. Every explosive item also receives a compatibility group letter, running A through S with I skipped, that governs which items can safely share storage or transport space. Mixing incompatible groups risks turning a single accident into a chain reaction. The letter reflects the item’s physical construction and chemical composition, not just its blast potential.⁴

A few of the most commonly encountered groups show how the logic works:

Group A is primary explosive substances, the most sensitive initiating materials. These must be isolated from virtually everything else.
Group B is articles containing a primary explosive without two or more protective features, such as certain detonators and primers.
Group D is secondary detonating explosives or black powder without means of initiation. Many common military munitions fall here.
Group G is pyrotechnic substances, including illuminating, incendiary, and smoke-producing articles.
Group K is articles containing both an explosive and a toxic chemical agent. These demand specialized handling beyond normal explosive safety precautions.
Group S is substances or articles packed or designed so that any accidental functioning does not significantly interfere with firefighting or emergency response in the immediate area.

Reading the Classification Code

The division and compatibility group combine into a single classification code, written as the division number, a period, and the group letter: 1.1D, 1.3G, 1.4S, and so on. Across all divisions and groups, 35 codes are possible.² That code, once assigned, is what the storage planner, the transportation officer, the shipping paperwork, and the firefighter all key off. Almost every downstream safety decision starts by reading it.

How Items Get Classified

Classification is a testing exercise, not a paperwork one. For Divisions 1.1 through 1.4, an item must undergo UN Test Series 6, which includes three core test methods (6a, 6b, and 6c) designed to evaluate mass explosion behavior, fragment projection, and fire effects under controlled conditions.² An additional test, 6d, determines whether a Division 1.4S classification is appropriate for certain items.

Test results normally go to the Pipeline and Hazardous Materials Safety Administration (PHMSA), whose scientists evaluate the data and issue a formal classification letter with an assigned EX Number. DoD and the Department of Energy have an alternative: they can self-classify their own explosives rather than route them through PHMSA, provided they follow the same standards in 49 CFR 173.56.⁵

Once a DoD item is classified, the data is recorded in the Joint Hazard Classification System (JHCS), which serves as the authoritative database for hazard division assignments, storage group information, and related safety data.⁶ If you need the current classification of a specific DoD item, JHCS is where it lives.

Interim Hazard Classifications

Not every item has a final classification when it first needs to move. DoD agencies listed in TB 700-2 are authorized to assign an Interim Hazard Classification (IHC) so that explosive materials can be transported before a final determination is issued.⁷ IHC shipments still have to meet all DoD and DOT transportation hazard classification and packaging requirements. The IHC is a temporary bridge; the item eventually requires full testing and a final classification before it can enter routine storage and distribution.

What the Classification Drives

The reason the classification receives so much attention is that it feeds directly into three separate compliance regimes: siting distance, fire response, and transportation.

Quantity Distance

Quantity Distance (QD) sets the minimum separation between an explosives location and any exposed site, whether that is an inhabited building, a public road, or another magazine. The calculation uses a cube-root scaling formula, D = K × W^1/3, where D is the required distance in feet, W is the Net Explosive Weight in pounds, and K is a factor reflecting the level of risk acceptable for the exposed site.⁸ A higher K-factor applies to more sensitive exposed sites, such as housing areas, and produces a longer required distance. In metric units the formula becomes D = K_m × Q^1/3, where Q is the net explosive quantity in kilograms; the English K-factor is roughly 2.52 times the metric K_m. The hazard division tells the planner which K-factor table to use in the first place.

Before building or modifying a facility that stores or handles explosives, the installation must submit site and construction plans to the Department of Defense Explosives Safety Board (DDESB) for review and approval.⁸ The requirement also applies to non-explosives facilities built within existing QD arcs, to mission changes that increase explosive hazards, and to any modification that changes the NEW, hazard division, or number of exposed personnel. The submission itself lists the NEW for each hazard division present, which is why an accurate classification has to be in hand before planning begins.⁹

Fire Division Symbols

Each hazard division maps to a DoD Fire Division, displayed on the exterior of storage locations as a geometric shape so responders can read the hazard at a glance. Fire Division 1 is the greatest hazard; risk decreases toward Fire Division 4.⁸

Fire Division 1 (octagon) is a mass detonation hazard and corresponds to Hazard Divisions 1.1 and 1.5. Firefighters should not fight the fire unless a rescue is planned and the senior fire officer approves the attempt.
Fire Division 2 (cross) is a non-mass explosion with fragment hazard and corresponds to Hazard Divisions 1.2 and 1.6. Fire may be fought in its early stages with fragment protection in place.
Fire Division 3 (inverted triangle) is a mass fire with minor blast or fragment effects and corresponds to Hazard Division 1.3. The fire may be fought if explosives are not directly involved; white phosphorus munitions in this category may explode and produce toxic smoke.
Fire Division 4 (diamond) is a moderate fire with no blast or fragment hazard and corresponds to Hazard Division 1.4. Fire may be fought, but responders should expect minor explosions and hot fragments.

Separate chemical hazard symbols exist for items containing toxic agents, white phosphorus, or harassing agents, each carrying its own protective-equipment and approach-direction requirements.

Transportation and Placarding

Once an item leaves storage, its classification code drives packaging, marking, labeling, and the placards on the vehicle. Shipping papers must state the hazard class, division, compatibility group, and quantity for each load.⁷

Placarding rules split along the division line. Divisions 1.1, 1.2, and 1.3 require vehicle placarding regardless of quantity; there is no minimum weight, and even a single round in these divisions triggers placards on all four sides of the vehicle. Divisions 1.4, 1.5, and 1.6 are placarded only when a highway or rail vehicle carries 454 kg (1,001 pounds) or more aggregate gross weight in non-bulk packaging; below that threshold, no placard is required. Division 1.4S items get an additional break and may not require the EXPLOSIVES 1.4 placard at all. When a vehicle carries items from multiple divisions, only the placard for the lowest-numbered division needs to be displayed.³

Motor carriers hauling placarded explosives must also follow the driving and parking rules in 49 CFR Part 397.¹⁰ States and tribal governments may designate or restrict specific highway routes for non-radioactive hazardous materials, including Class 1 explosives, under Subpart C of that Part, and must report new or changed route designations to the Federal Motor Carrier Safety Administration within 60 days. Higher-hazard shipments may also require security escorts on public roadways, depending on the division and quantity.

Read backward from any of these requirements and the same fact keeps surfacing. The distance to the perimeter fence, the shape on the magazine door, the placards on the truck, the response the fire chief can make: each one is downstream of the two-part code assigned under TB 700-2.

1
Defense Technical Information Center (DTIC). Comments and Position Regarding the Proposed TB 700-2 Rewrite
2
eCFR. 49 CFR Part 173 Subpart C – Definitions, Classification and Packaging for Class 1
3
eCFR. 49 CFR 172.504 – General Placarding Requirements
4
eCFR. 49 CFR 173.52 – Classification Codes and Compatibility Groups of Explosives
5
PHMSA. Explosives
6
U.S. Army. Resource Links
7
Defense Logistics Agency. DLAR 4145.41 – Packaging of Hazardous Material
8
Department of Defense. DESR 6055.09, Edition 1, Change 1
9
DOD DENIX. DDESB Guidance for Explosives Safety Site Plans
10
eCFR. 49 CFR Part 397 – Transportation of Hazardous Materials; Driving and Parking Rules