M&G DuraVent’s DuraStack is a modular double-wall positive pressure chimney system. Fully tested and listed to UL 103, UL1978, ULC/ORD C959 and ULC S604, DuraStack offers versatility for a variety of applications including boiler breeching, engine exhaust, chimney stack and grease duct (model DIS only). The DuraStack DIS and DAS venting systems are cylindrical, prefabricated, modular venting systems incorporating a unique extended inner flange designed for quick assembly and pressure sealing capability. DuraStack DIS and DAS is composed of a thick-gauge material for the inner pipe and coupling, providing a strong and rigid assembly; a self-centering flue design that significantly simplifies and accelerates the installation process; and a coupling configuration (patent pending), requiring only one locking band and the use of a regular, less expensive, high-temperature silicone sealant.