An Alternative to Spiral Ductwork in Industrial Applications
Spiral Ductwork May Not Be Your Best Option
Spiral ductwork is an often specified and commonly known duct pipe style. As the name implies, the duct is formed by spiraling and locking strips of metal together to form a continuous piece. This forming method enables the manufacturer to produce various lengths of duct in less time, creating a duct that is typically less expensive than duct formed by rolling sheets. Yet, when considering ductwork options for your customers and looking at the entirety of the project from design, manufacturing, shipping, installation and ongoing maintenance, spiral duct may not be the best solution. Consider the information below and the possible alternative of Clamp Together Duct as a better solution.
As with many products that look cheaper on the surface, there are hidden costs associated with spiral AND hidden benefits from other types of ducts. Consider these facts prior to ordering.
- Spiral duct typically comes in lengths that are not conducive to handling, especially in larger sizes. While the long length may appear to provide faster installation, the truth is that the difficulty of maneuvering it into place increases exponentially with length. The difficulty of loading and unloading spiral duct from trucks increases with length as well.
- Spiral duct can be joined by various methods. None of them are easy.
- Flanges/Angle Rings- The problem with this process is that spiral duct is formed by locking edges of the metal together. This creates spirals of 4 thicknesses of metal. This thickness makes it virtually impossible to turn a van-stone edge (a ~1/2’ edge that is turned back at 90 degrees to the duct) or to compress the van-stone ends between the flanges.
- Flanges can be welded on- but only if the spiral is of sufficient gauge AND the installer is good at welding lighter gauge metal.
- Crimping- This method involves crimping one end and forcing it into the adjoining piece. The joint is then taped or screwed together in order to hold it together. This is neither easy nor effective in making a tight fit. It also requires exact measuring and if screws are used, leaves protrusions into the duct.
- Using collars. The collars are typically made to slide into the ends of the joining duct. Not only are these collars expensive, but they also require tape or screws to hold them together. Additionally, this leaves a protrusion in the duct. Big end/small end collars eliminate this by allowing the collar to be slid into one duct and over the other (in the direction of the air flow) but these are even more expensive- and still require tape or screws.
- Spiral fittings (elbows, branches, etc.) can be made with big end/small end connections and eliminate using collars when joining fittings to the straight duct but collars are still necessary for joining straight duct. Both fittings and straight duct also require tape or screws to secure the connections.
- In all instances above, exact cuts are required. And while the straight duct is cheaper, the branches, elbows and other fittings are no cheaper than other systems.
- Clamp Together Duct is more expensive than spiral duct but usually the difference in price is only in the straight duct. The fittings are approximately the same price. The clamps DO add cost to the system BUT only in the metal product- NOT the project.
- A mower is more expensive than a sickle, not only because it has more parts but because the labor is taken out of the process. Such is the case with Clamp Together Duct. The rolled lips and clamps add cost to the product BUT enable the pieces to be clamped together in a fraction of the time- typically 70% less than either spiral or flanged duct.
- The adjustable sleeve also adds cost but enables the installer to adjust for length variations up to 10”. Though correct measurement is always desired, it rarely happens. With spiral duct, a mistake can mean the discarding of the duct. With Clamp Together Duct, the mistake is corrected by sliding the adjustable sleeve on the pipe to vary the length.
- All fittings have the ability to receive a cut piece of pipe, increasing the ability to make infinite adjustments.
At US Duct, we know more about Clamp Together Duct than anyone. It is available in sizes 3”-24”, galvanized and SS, and standard and heavy (up to 10) gauge. We provide ALL components and special fittings. The system is infinitely adjustable, with adjustment capability built into EVERY fitting. While Clamp Together Duct is often the fastest, easiest and cheapest way to address dust/mist collection, it is often best used in conjunction with other connection methods as dictated by application or duct size. Our extensive knowledge will enable you to get the best solution for the application AND the money -using the duct that fits your application best.
Contact US Duct, or visit our FAQ page for even more information.