MDI Transportation Guidelines - Polyurethanes - American ...

MDI transportation
g u i d e l i n e s
Chapter 4: Design and Construction of Transportation Equipment
and Packaging
4.1 Rail Tank Cars (RTCs)
Rail tank cars used for the transportation of MDI must meet the U.S. Department of Transportation’s design
and construction requirements for the transportation of hazardous materials. These requirements are found in
49 CFR Part 179. The various subparts of Part 179 describe the requirements for construction material,
welding, wall thickness, gaskets, valves, valve protection, and venting devices.
Specific additional recommendations are as follows:
• All fittings on Rail Tank Cars should be clearly labeled.
• Tanks should be thermally insulated to minimize temperature fluctuations and provide extra protection in
the event of fire or other accident.
• Heating coils should be located on the exterior of the tank.
• Tanks may be constructed of mild steel. The tanks may be internally lined.
• Tanks should be fitted with 2-inch connections for vapor return lines.
• Although the DOT’s Hazardous Materials Regulations permit bottom outlets, diisocyanate producers
recommend only top outlets.
• Pressure relief valves should be present and should be set to 75% of the pressure rating of the tank car.
• If present, vacuum relief valves should be utilized to prevent negative internal pressure and should be set
to 1 psig.
• External fittings should have rollover or crash protection so that the tank car will not leak when involved
in an accident.
• Thermowells for temperature measuring devices should be present and have the appropriate relief
devices to prevent spraying of product in the event of a malfunction of the thermowell.
• Fittings should be available for pressurizing the car with dry nitrogen or dry air to assist in unloading or
to apply a nitrogen blanket to prevent moisture ingress.
• To prevent product contamination, it is recommended MDI not come in contact with aluminum, brass,
copper, zinc, or their alloys.
4.2 Cargo Tanks (Tank Trucks) and Inter-modal Bulk Tank Containers (ISOTainers)
Cargo Tanks used for the transport of MDI must meet the design and construction requirements of the U.S. DOT.
When MDI is shipped in a DOT specification container permitted by 49 CFR Part 173, it must conform to the
applicable design specifications in Part 178.
• Each tank must be fitted with a pressure relief device.
• Each tank should be fitted with vacuum relief devices as prescribed in the appropriate section of the
DOT’s regulations.
Copyright 2001, American Plastics Council
11