FLASHING B VENT 8" 0 6 TO 6 12 PITCH HART & COOLEY (4)Gas Vent Pipe; Type Type B Gas Vent, Double Wall, Round; Material Aluminum. Temperature Rating 400 Deg F; Inclusions/Features Installation Instructions are Supplied with Cap and Support; Applicable Standard UL 441; Clearance 1 Inch. The Hart & Cooley® double-wall, air-insulated B-Vent system is secured by locking joints . Properly installed, the vent wont come apart through vibration, and offers protection against vent failure or fire hazard . Type B Gas Vent is designed for negative pressure applications and flue gas temperatures not exceeding 400°F above ambient for Category I appliances .