The DOT-117J100W tank car is required to have a thermal protection system. Thermal protection systems, including a reclosing pressure relief device, consist of high temperature-resistant material used to minimize the rate of temperature transfer to the tank wall and the commodity when exposed to the conditions of an exterior fire. The most common form of thermal protection for tank cars is a layer of 1/2-inch ceramic fiber applied to the exterior surface of the tank.
While thermal protection is required, insulation is optional for the DOT-117J100W. Insulation is used to minimize changes in product temperature during transport. The most common form of insulation is four-inch-thick fiberglass. However, it can be applied in greater thickness if necessary.
The entire thermal protection system and insulation must be covered by a steel jacket with 11-gauge minimum thickness. The jacket prevents deterioration of the thermal protection and insulation caused by weather. The tank heads of DOT-117J100W require puncture resistant systems, which are achieved by applying 1/2-inch-thick full-height head shields.