Dissecting Tank Car Types & Markings

tank car

Ever wonder what all those markings on the side of a tank car mean?  It’s actually easier to understand than you would think.  These markings consist of a reporting mark, capacity stencil and a specification mark.

Let’s start with the first and best identifier of a tank car.  The reporting mark identifies the car’s owner and the car itself.  It is an alpha code of one to five letters for the car’s owner along with a one to six-digit number that identifies the car.  (By the way, if there is an “X” as the last letter, it indicates the car is privately owned and not the property of a railroad company.)


Marks are found on both sides and both ends of a tank car.  On the sides, they are to the left as you face the car.  As a newer industry initiative, sometimes they are found on the top of the cars too.

Another marking is the load limits.  LD LMT is the maximum weight car and lading.  LT WT is the weight of the car without the lading.  The capacity stencil is the capacity of the tank car, not how much product is in the car.  It will be listed in gallons and liters and found on both ends of the car.  The water capacity markings or water capacity stencil are on the side of the car.  The specification marks indicate the standards to which the tank car was built.  These markings are found on the right of the tank as you face the side.

In summary, the specification mark shows the authorizing agency, the class number or type of car, the Delimiter letter, the tank test pressure, material of construction if not carbon steel, weld type and fittings, materials and lining.