Ask X3What does 49 CFR 178.276 (Requirements for the design, construction, inspection and testing of portable tanks intended for the transportation of non-refrigerated liquefied compressed gases) require?
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As a motor-carrier owner operating portable tanks for non-refrigerated liquefied compressed gases, you must comply with the design, construction, inspection, and testing requirements specified in 49 CFR 178.276.
Here are the practical requirements for your tanks:
* Design and Construction Standards: Shells must be made of seamless or welded steel (or a combination), have a water capacity greater than 450 liters (118.9 gallons), and be designed, constructed, certified, and stamped according to Section VIII of the ASME Code.
* Pressure and Calculations: Your tanks must meet specific engineering standards for design pressure, design reference temperature, filling density, and Maximum Allowable Working Pressure (MAWP) as outlined in the regulation.
* Heat Treatment and Radiography: Tanks must be postweld heat-treated and radiographed per the ASME Code as a single unit after all welds to the shell and heads are completed. Tanks used for anhydrous ammonia must be postweld heat-treated at a tank metal temperature of at least 1050 °F. Tanks built under part UHT of the ASME Code have additional strict annual welding tests and lot-based impact testing requirements.
* Thermal Insulation: If your tanks use thermal insulation, they must include a device to prevent dangerous pressure buildup from leaks (with gas-tight protective coverings when closed). Insulation must not block access to fittings and must either be a shield covering the upper third to upper half of the shell with a ~40 mm air space, or a complete cladding system that prevents moisture and has a thermal conductance of no more than 0.67 (W·m⁻²·K⁻¹).
* Service Equipment and Shut-Off Devices: Tank openings larger than 1.5 mm (0.1 inch)—excluding pressure-relief, inspection, and bleed holes—must have three mutually independent shut-off devices in series:
1. An internal stop-valve, excess flow valve, or similar feature.
2. An external stop-valve.
3. A blank flange, threaded cap, plug, or equivalent liquid-tight closure.
* Valves Below the Liquid Level: Filling and discharge openings located below the liquid level require an internal stop-valve as the first device, paired with a second stop-valve in an accessible position on each pipe. For flammable or toxic gases, this internal stop-valve must be a self-closing safety device that automatically shuts fully in a fire (within 30 seconds of actuation at a temperature of no more than 121 °C / 250 °F). Excess flow valves must be mounted to maintain effectiveness upon impact and automatically close at the manufacturer's rated flow.