Are all hazardous-material shippers and carriers required to register with the Pipeline and Hazardous Materials Safety Administration (PHMSA)?

No, only shippers and carriers that meet certain requirements must register. PHMSA registration requirements apply to anyone that offers for transport or transports in foreign, interstate, or intrastate commerce any of the following:

Any highway route-controlled quantity of a Class 7 (radioactive) material;

More than 55 pounds of a Division 1.1, 1.2, or 1.3 (explosive) material;

More than 1.06 quarts per package of a material poisonous by inhalation (as defined by Section 171.8 that meets the criteria for “hazard zone A” as specified in Sections 173.116(a) or 173.133(a));

A shipment (offered or loaded at one loading facility using one transport vehicle) in a bulk packaging having a capacity equal to or greater than 3,500 gallons for liquids or gases, or more than 468 cubic feet for solids;

A shipment (offered or loaded at one loading facility using one transport vehicle) in other than a bulk packaging of 5,000 pounds gross weight or more of one class of hazardous material for which placarding is required; or

A quantity of hazardous materials that requires placards, except farmers in direct support of farming operations.