DOT-117 Tank Car Insulation

This primer provides a clear, technically grounded overview of tank car insulation systems and the DOT-117/TC-117 standard that governs the transport of Class 3 flammable liquids in North America. It explains how modern tank cars are constructed, how thermal protection systems function during normal operation and fire exposure, and why insulation plays a central role in preventing catastrophic tank failure. The document reviews the regulatory framework in the United States and Canada, summarizes notable rail incidents that shaped current requirements, and outlines key elements of testing, inspection, and maintenance.

The primer also examines emerging trends, including advanced insulation materials, real-time sensor monitoring, and potential applications for hydrogen and cryogenic service. A 10-question knowledge check reinforces the major concepts.

This guide is intended for railroad professionals, energy-industry engineers, emergency planners, fire departments and anyone seeking a concise, practical understanding of tank car thermal protection and the evolution of DOT-117 standards.