On July 5, 1973, workers at the Doxol Gas Distribution Plant in Kingman, Arizona, began what should have been a routine job: transferring propane gas from a railway car into storage tanks. A series of small events and errors, however, snowballed into a massive tragedy that is still used as a warning in training material for industrial workers and fire departments across the country, and led to changes in industrial regulations. Tank Car #38214, filled with 33,000 gallons of propane, was left sitting out in the hot sun in a…