A tank car is a railroad car that is used to transport liquids, and it is able to transport a variety of items including food as well as volatile chemicals and petroleum products. Placards or signs on the tank car warn of the dangerous material being transported. Some tanks are pressurized and some are even heated. Heating the car allows thick, viscous products to be more easily unloaded.
Due to the dangerous nature of the products transported in some tank cars, the grab rails and steps that are part of the tank car are designed so that a railroad worker cannot climb aboard while the train is in motion. This is the only such railroad car with this design trait. Due to the nature of many tank car payloads, most rail companies have strict orders as to what type of freight cars can be linked to and from the tankers. Limits on how many tankers can be linked together are also in effect on most lines.
The tank car undergoes special certification inspections to assure that it is safe to transport hazardous materials through cities and towns. Different materials require different certifications, depending on the nature of the freight. Hatches as well as loading and discharge valves must all be inspected to meet certification. Inspection cards are displayed on each car denoting certification date and results.
Some tank cars that are used to transport liquid oxygen and other gases are kept cold by on-board generation and refrigeration units. These refrigeration tankers are often covered with a thick coating of foam insulation. The insulation helps to maintain the temperature of the tank car as well as allow the cooling unit to operate at a reduced level. Some food items, such as milk, are also routinely transported in a cold tank car.
Most tank cars are washed inside and out after being unloaded. This procedure assures that the car is ready for the next cargo and will not contaminate the product being transported. Cars used for food-grade products must be certified clean and carry an identification tag showing the inspection time and date. Cars failing to display this data may be refused and rejected at the loading dock.
Whether it be fuel to operate domestic vehicles or to power military machinery around the world or corn syrup to sweeten candy around the globe, the tank car serves a very useful purpose. Traveling millions of miles in caravans of railroad cars, the tanker is one of the most recognizable vehicles in the world.