Refers to equipment, structures, or vessels provided with an encapsulating material that, for the expected duration of fire exposure, will limit steel temperatures to a maximum of 850oF (454oC) for structural members or 650oF (343oC) for vessels. The insulation system shall be: (1) Noncombustible and fire retardant; (2) Mildew and weather resistant; (3) Resistant to the force of hose streams; and (4) Secured by fire and corrosion-resistant fastenings