Double-Wall, Insulated Round and
Flat Oval Duct and Fittings

McGill AirFlow's double-wall, insulated duct and fittings provide exceptional noise and thermal control in air handling systems. They are constructed of a solid sheet metal outer pressure shell and a sheet metal inner liner with a layer of insulation sandwiched between.

We offer double-wall, round duct in three outer shell constructions: spiral lockseam, spiral lockseam with a standing rib, and longitudinal seam. Double-wall, flat oval duct is available in spiral lockseam and longitudinal seam constructions.

View chart of McGill AirFlow's Duct and Fitting Construction Methods

Our standard double-wall duct and fittings have galvanized sheet metal outer walls and a layer of fiberglass insulation surrounding the inner liner. The insulation is available as standard fiberglass or Acousti-Line™ insulation with an acrylic coating that resists air erosion of fibers and the growth of fungus and bacteria. Standard duct has a perforated metal inner liner, while standard fittings have a solid metal inner liner. Options include other thicknesses and types of insulation, stainless steel and aluminum outer walls, and specification of solid-wall or perforated-wall inner liners as nonstandard items.

These options and the numerous sheet metal gauges that are available enable McGill AirFlow to provide double-wall duct and fittings for a wide range of environments, including hospitals, laboratories, food and pharmaceutical plants, and corrosive industrial areas. We also supply systems to convey hot air and gases, even when temperatures exceed 1,000°F.

UNI-GASKET fittings


Acoustical Benefits
Thermal Benefits
Mechanical Benefits


McGill AirFlow's Double-Wall, Insulated Round and Flat Oval Duct and Fittings:

Double-Wall, Round Duct
Double-Wall, Round Fittings
Double-Wall, Flat Oval Duct
Double-Wall, Flat Oval Fittings



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An enterprise of United McGill Corporation—Family owned and operated since 1951

Unless otherwise noted, all (™) trademarks and (®) registered trademarks are property of United McGill Corporation.

Products depicted were current at the time of publication. All product designs, specifications, and features are subject to change without notice.