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Cylinders are pressurized containers used to transport hazardous materials. The fact that the gas inside is under pressure presents a hazard. Additionally, sometimes cylinders hold gases with other hazardous properties, for example, corrosive or flammable gases. Cylinders must meet certain specifications in order to be used to transport hazardous materials.
Scope
For safety purposes, cylinders must be designed, inspected, and maintained according to the hazardous materials regulations. Shippers must ensure they’re using cylinders appropriate for the material and that the cylinder is in good condition.
Regulatory citations
- 49 CFR 171.8 — Definitions and abbreviations
- 49 CFR 173.301 — General requirements for shipment of compressed gases and other hazardous materials in cylinders, UN pressure receptacles and spherical pressure vessels
- 49 CFR Part 178, Subpart C — Specifications for cylinders
- 49 CFR Part 180, Subpart C — Eddy current examination with visual inspection for DOT 3AL cylinders manufactured of aluminum alloy 6351-T6
Key definitions
- Cylinder: A pressure vessel designed for pressure higher than 40 psia that has a circular cross-section. This does not include a portable tank, multi-unit tank car tank, tank car, or cargo tank.
- Hazardous material: A substance or material capable of posing an unreasonable risk to health, safety, and property when transported in commerce, including hazardous substances, hazardous wastes, marine pollutants, elevated temperature materials, materials designated as hazardous in the Hazardous Materials Table (49 CFR 172.101), and materials that meet the defining criteria for hazard classes and divisions in 49 CFR Part 173.
Summary of requirements
Section 173.301 covers the general requirements for the shipment of compressed gases and other hazardous materials in cylinders, UN pressure receptacles and spherical pressure vessels. This section includes the general specifications for cylinders, cylinder markings, pressure relief device systems, manifolding cylinders during transportation, and valve protection requirements.
The specifications for construction of cylinders can be found in Part 178, Subpart C of the Hazardous Materials Regulations.
Cylinders are required to undergo certain tests and inspections. For more information see Part 180, Subpart C.
Cylinders are required to be properly marked and labeled for transport. Placards may be required for transporting certain loads of cylinders. For information on these topics see the ez Explanations Marking, Labeling, and Placarding.