The Increased use of Spiral Flanges (and the decreased use of Slip Couplings) for Job Site speed

Rolled Carbon Steel Prepunched Angle Iron Rings are used in joining ductwork together. Conklin stocks diameters ranging from 3" to 59", manufactured by Midwest Metal Products. Larger sizes, as well as Galvanized, Aluminum, and Stainless Steel Rings, are also available with very short lead times.

When it comes to Single Wall Spiral Duct, contractors typically attach one piece to another on the job site with a Slip Coupling and screws. However, the larger the diameter, the more challenging it is to use slip couplings, and the quality of connection is rarely good. As a rule of thumb, these contractors use field-installed slip couplings up to a certain size (typically 16") and then move to a flange.

When SpinFinity introduced the AccuFlange, many sheet metal contractors started attaching this flanged connection on each end of larger diameters of spiral pipe before it went out to the job site.

The shop drills screws through the spiral pipe and through the flange, which has one leg inside the pipe and the other leg perpendicular at a 90-degree angle, mating with the adjoining piece of pipe.

After getting a taste of the ease of hanging duct that had flanged end connections already installed, plus not having to keep track of the slip couplings, the chorus started growing from the field crew for the spiral pipe and fittings to have flanged ends.

As more emphasis seems to be moving towards doing as much in a controlled environment (the duct fab shop) versus an uncontrolled environment (the field), the increase of spiral flange connectors is likely to keep gaining momentum. While contractors may opt for the less expensive slip couplings for all of their single wall spiral, flanged connections are prevalent when it comes to double wall spiral. Usually attached in the shop, these could also be attached in the field if the contractor buys his pipe from one source and his flanges from another. Attaching in the shop saves field labor and avoids damage likely to happen to pipe and fittings that have raw edges.

Double Wall Flanged connections look just like Single Wall connections when hung.

The increase of Double Wall jobs being specified by engineers means that Double Wall Spiral Flanges are here to stay. Like Single Wall Flange, it slides inside the outer wall and is attached with drill screws around the pipe.

The longer inner sleeve may seem confusing to some, but the value of that inner sleeve being longer is all about the ease of installing the flange. When the inner sleeve is longer, it's much easier to get the flange started in the pipe since it doesn't fit smoothly every time. The longer inner sleeve allows for more visibility of where it's off and needs to be worked in.