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. But, the larger the diameter the more of a challenge 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 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 jobsite.
The shop drills screws thru the Spiral pipe and thru the Flange which has one leg inside pipe and the other leg perpendicular at a 90 degree which will mate to 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) vs an uncontrolled environment (the field), the increase of Spiral Flange connectors is likely to keep gaining steam. While contractors may opt for the less expensive slip couplings on all of their Single Wall Spiral, when it comes to Double Wall Spiral, Flanged connections are prevalent. 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 shop makes 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 is longer it’s a lot easier to get the flange started in the pipe since it doesn’t fit smoothly in every time. The longer inner sleeve allows more visibility of where it’s off and needs to be worked in.
