Molten metals, flammable substances, and high levels of radiation exposure all require heavy-duty, high-heat protective clothing to prevent or delay injury.Heat sources such as steam and water vapor have the potential to infiltrate the garment, so seam construction in thermal garments is critical when fabric penetration is not the only risk.From thermochemical protection classes, to fully encapsulated aluminized suits, determining the type of thermal energy and the potential level of thermal energy transfer should be the first assessment to determine the proper thermal protection required.