TSA Rail Transportation Security Rule
DOT HM-232

DOT HM-232 Applicability

Each facility that offers for transportation in commerce a threshold quantity of one or more of the hazardous materials delineated in the chart below must develop and adhere to a hazardous materials transportation security plan.

Hazard Class/Division


Threshold Quantity

Division 1.1, 1.2, and 1.3


Any Quantity

Division 1.4, 1.5, and 1.6


Any Quantity Requiring Placarding

Division 2.1

Flammable Gases

Large Bulk Quantity

Division 2.2

Nonflammable Gases

Large Bulk Quantity with Subsidiary Hazard of Division 5.1 Oxidizer

Division 2.3

Poisonous Inhalation Hazard (PIH)

Any Quantity

Class 3 and Division 4.1

Desensitized Explosives

454 kg (1,001 pounds) or Greater in a Single Transport Vehicle or Freight Container

Class 3

Flammable Liquids

Large Bulk Quantity in Packing Group I or II

Division 4.2

Spontaneously Combustible

Large Bulk Quantity in Packing Group I or II

Division 4.3

Dangerous When Wet

Any Quantity

Division 5.1


Large Bulk Quantity in Packing Groups I and II

Division 5.2

Organic Peroxides

Any Quantity of Organic Peroxide, Type B, Liquid or Solid, Temperature Controlled

Division 6.1

Poisonous Materials Other than PIH

Large Bulk Quantity in Packing Groups I, II, and III

Class 8

Corrosive Materials

Large Bulk Quantity in Packing Group I

Class 9

Miscellaneous Hazardous Materials

Not Subject

Note that a “large bulk quantity” is any quantity greater than 3,000 kg (6,614 pounds) for solids or 3,000 liters (792 gallons) for liquids and gases in a single packaging such as a cargo tank motor vehicle, portable tank, tank car, or other bulk container.

Contact us

Do You Have any Questions?

Need Help?
Get in touch with us


2234 Richmond Ave., Houston,
TX 77098

Phone number
(713) 572-3600