Rectangular-k27® Duct and Fittings

McGill AirFlow's Rectangular-k27 duct and fittings provide exceptional noise and thermal control in air handling systems. This double-wall, insulated ductwork is constructed of a solid metal outer pressure shell and a metal inner liner with a layer of insulation sandwiched between. The acoustical/thermal insulation can be used with air velocities up to 10,000 fpm and temperatures up to 250°F. It is available in thicknesses of 1, 2, and 3 inches and has a maximum thermal conductivity (k) factor of 0.27 Btu/hour/square foot/°F/inch thickness. Our standard construction is galvanized steel with a perforated metal liner and 1-inch-thick uncoated fiberglass insulation. Other insulation materials and metals are available, as are solid metal inner liners. Rectangular-k27 duct and fittings are shipped fully assembled with TDC™ transverse duct connector flanged ends.

Rectangular-k27 group photo

Available Materials and Thicknesses

Construction (1)
Materials (2, 6)
(outer shell)
Galvanized Steel
28-18 gauge (4)
Stainless Steel
26-22 gauge (5)
0.032-0.063 inch
Rectangular-k27 (3)
(metal inner liner)
Galvanized Steel
24-20 gauge
Stainless Steel
24-20 gauge
0.040-0.063 inch

(1) Both outer pressure shell and metal inner liner incorporate Pittsburgh lockseam construction and TDC end connectors. Ductwork is fully assembled with a finished length of 56 1/4 inches or 68 1/4 inches.

(2) When steel is used, the outer pressure shell and metal inner liner can be made of different types of steel. When aluminum is used, both the outer pressure shell and metal inner liner must be aluminum.

(3) Standard duct and fittings metal liner is perforated galvanized steel.

(4) Galvanized steel fittings with Pittsburgh lockseam construction are also available in 14 gauge.

(5) Stainless steel fittings with Pittsburgh lockseam construction are also available in 20 gauge.

(6) SilverGuard™ rectangular, double-wall duct and fittings are available on special order.

SilverGuard Antimicrobial


McGill AirFlow's Rectangular-k27® Duct and Fittings:

Erosion Resistant
Special Air Quality Options
Standard Design


TDC™ is a trademark of Lockformer Company.


© 2002-2015 McGill AirFlow LLC
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.