Safe Loading of Liquid Rail Cars - Best Practices

Best Practices for the Safe Loading of Liquid Rail Cars

Statistical analysis shows that 80% of transport-related accidents and incidents occur during loading and unloading operations. This guideline offers best practice advice on loading and unloading from an organizational and behavioral point of view.

Drivers that access chemical sites for the purpose of (un)loading must follow site procedures in co-operation with their operators. These can involve working in flammable atmospheres.

1. Loading Procedures

It is important to be familiar with all loading procedures and know the weight and pressure restrictions for each type of tank car. This allows the crew to be aware of all necessary precautions to take when loading and unloading. Loading/unloading operations should be attended and monitored by trained personnel or by an approved monitoring system. Do not allow the load/unload operation to stand unattended or unmonitored while connections are being attached.

Before a tank car is loaded, all safety equipment should be checked to ensure it is in good working order. All hoses, fittings and valves should be properly secured in the closed position. The magnetic gauge cover and thermometer well cap must be hand tightened. If the tank car is equipped with an auxiliary bottom outlet valve and plug, it must be left off during the entire loading process (unless otherwise authorized).

It is also recommended that all fittings’ seals are examined for evidence of tampering or leakage. If a vapor valve is open, it should be vented to a scrubber or vapor collection system. If the tank is being used to transport a hazardous material, the top openings should be sealed with the proper DOT plugs. In addition, any plugs on the interior heater coil inlet outlet pipes must be replaced and the caps for these outlets should be tightened.

2. Bottom Outlets

Most rail tank cars have bottom outlets to allow for pump off-loading. Whether the car is insulated or not, these outlets should be closed and any auxiliary valves open while loading. Also, be sure that the cap and plug on these connections are properly sealed.

Some tank cars are equipped with heater coils to heat viscous liquids (like syrups or asphalt) so they can be loaded easier. These are in the bottom of the car, usually on both sides, and you may see extra hookup connections to accommodate these coils. These connections should be clearly marked so that people are not confused about which is liquid and which is vapor return. Loading a car with the connection marked as liquid connected to a vapor-return line will immediately flood that line with product and could cause an explosion.

When using a bottom outlet, it is a good idea to place the railcar on a track pan or put down a bucket or spill pad in case of leakage. It is also a good idea to keep the operating handle locked in a closed position.

In addition, the tank car should be positioned on a flat surface to prevent rolling and possible damage to the car or piping. Lastly, the tank car should be secured with straps or cables to prevent unintentional shifting during transport.

3. Filling Connections

Rail tank cars are specialized pieces of equipment. They can only carry certain kinds of cargo, and are generally "one-way" cars (they cannot be reloaded for the return trip). Because of this specialization, tank car design is designed to meet specific requirements. For example, they may be equipped with heater coils to heat up viscous liquids like syrups, asphalt, and heavy oils so that they will flow more easily through the bottom drain valve.

These heater coils, and other components of the car, must be properly grounded to prevent static electricity from causing ignition during loading and unloading operations. They must also be insulated to protect against the possibility of fire from flammable vapors leaking from the top or bottom connections of the tank. During loading and unloading, the car should be continuously attended to by a person or monitored by an approved monitoring system.

It is also important to note that the tank car's DOT hazard class and division placard must be conspicuously displayed. This placard should be readily recognizable to train crews and emergency response personnel who may come upon the car in an accident or disaster. This is done by displaying the DOT placard in a prominent location on the front, rear, and sides of the tank car. In addition, the tank must be built to withstand exposure to weather and in-train and switching forces as well as vibrations and dynamic forces. PHMSA is authorizing in this final rule rail transportation of LNG, a well characterized and understood material, in DOT-113C120W-specification tank cars with enhanced outer tanks made from thicker TC-128B normalized steel (marked by the specification suffix 9). These enhancements have been shown to improve crashworthiness.

4. Safety Devices

A tank car can carry a wide range of chemicals, but each type requires special safety devices to protect the environment and ensure safe transport. The best choice for liquid transport is a highly impermeable lining that can withstand a variety of conditions without leaking or compromising the safety of the cargo within. Loading rail cars with the right lining also increases the versatility of the transportation unit, which may increase revenue streams by enabling the same car to carry multiple chemicals.

Other important safety features include flame arrestors on supply headers in loading racks and marine dock piping to prevent flashback; and electrical bonding and grounding at truck and rail loading facilities to neutralize static electricity. In addition, insulating flanges are used on piping connections for tank trucks and tank cars to prevent the flow of flammable vapor.

Lastly, the design and layout of tank car loading racks should be considered. Racks that load flammable or combustible liquids should be located away from truck traffic and other areas of the plant and must be spaced to minimize road blockage when spotting rail cars for transport, and to always allow passage for fire trucks and other service vehicles. Tank car loading racks that handle low-flash materials should be spaced at least 60 meters from process equipment that handles hydrocarbons, and 45 meters from other types of tank car loading racks.