Concept
A tank car (International Union of Railways (UIC): tank wagon) is a type of railroad car (UIC: railway car) or rolling stock designed to transport liquid and gaseous commodities. The following major events occurred in the years noted: 1865: Flatcars with banded wooden planks or decking mounted on top are employed for the first time to transport crude oil from the fields of Pennsylvania during the Pennsylvanian oil rush. Laurence Myers of Philadelphia invented the Rotary Oil Car, as he named it. It was an improvement on a patent from 1851 of a freight car for transporting coal. The new invention patented on July 18, 1865, was for the transportation of crude oil and petroleum. It was the first appearance of an oil tank on a railroad flatcar. Three books mention his invention. 1869: Wrought iron tanks, with an approximate capacity of per car, replace wooden tanks. 1888: Tank-car manufacturers sell units directly to the oil companies, with capacities ranging from . 1903: Tank-car companies develop construction safety standards. More than 10,000 tank cars are in operation. 1915: A classification system is developed by the tank-car industry to ensure the correct match of car type to product being shipped. Some 50,000 tank cars are in use. 1930: 140,000 tank cars transport some 103 commodities. 1940s: Virtually every tank car is engaged in oil transport in support of the war effort. 1945–1950: Welding replaces riveting in car construction (both underframes and tanks) for the major manufacturers, including American Car & Foundry and General American. 1950: Pipelines and tank trucks begin to compete for liquid transport business. 1963: The Union Tank Car Company introduces the "Whale Belly" tank car. Many variants exist due to the wide variety of liquids and gases transported. Tank cars can be pressurized or non-pressurized, insulated or non-insulated, and designed for single or multiple commodities. Non-pressurized cars have various fittings on the top and may have fittings on the bottom. Some of the top fittings are covered by a protective housing.
