What does 49 CFR 173.40 (General packaging requirements for toxic materials packaged in cylinders) require?

As your fleet-compliance assistant, here is what 49 CFR 173.40 requires for motor-carrier owners transporting Hazard Zone A or B toxic materials in cylinders:

* Authorized Cylinders: You must use a cylinder that conforms to a DOT specification or UN standard (in subpart C of part 178), or an authorized TC, CTC, CRC, or BTC cylinder. Acetylene and non-refillable cylinders are strictly prohibited. Additionally:

* UN tubes and MEGCs are prohibited for Hazard Zone A materials.

* Specification 3AL cylinders made of aluminum alloy 6351-T6 are prohibited for Division 2.3 or 6.1 Hazard Zone A materials.

* UN composite cylinders certified to ISO-11119-3 are not authorized for Division 2.3 Hazard Zone A or B materials.

* UN seamless cylinders used for Hazard Zone A materials have a maximum water capacity of 85 liters.

* Outage and Pressure: For DOT specification cylinders, the pressure of Hazard Zone A and B materials at 55 °C (131 °F) cannot exceed the cylinder's service pressure. You must also leave enough outage (empty space) so the cylinder is not liquid full at 55 °C (131 °F).

* Closures: Cylinders with Hazard Zone A materials must use specific plugs or valves:

* Plugs and valves must have a direct taper-threaded connection to the cylinder and withstand the cylinder's test pressure without damage or leakage (UN pressure receptacles may use other means meeting ISO 10692-2).

* Valves must generally be packless with a non-perforated diaphragm (corrosive materials may use packed valves if made gas-tight with a seal cap and gasketed joint).

* Valve outlets must be sealed with a threaded cap or solid plug and inert gasketing material.

* All construction materials for the cylinder, valves, plugs, outlet caps, luting, and gaskets must be compatible with each other and the lading.

* Valve Damage and Handling Protection: Cylinders or overpacks containing Division 2.3 or 6.1 Hazard Zone A or B materials must meet specific drop-test and protection standards:

* DOT cylinders with wall thicknesses under 2.03 mm (0.08 inch) or without fitted valve protection must be overpacked in a box strong enough to prevent deformation or breakage from a 2.0 m (7 ft) drop onto a non-yielding surface like concrete or steel.

* DOT cylinders with valves must have a protective metal or plastic cap, another valve protection device, or an overpack capable of protecting the valve from a 2.0 m (7 ft) drop onto a non-yielding surface.

* UN cylinders must meet specific test pressures and minimum wall thicknesses (3.5 mm for aluminum, 2 mm for steel), or be packed in a rigid outer packaging meeting Packing Group I performance levels.

* Interconnection: Cylinders cannot be manifolded or connected together (except for MEGCs containing Hazard Zone B materials under § 173.312).