Spiral Ductwork

Spiral ductwork is the most efficient mode to transport air in HVAC systems. Spiral pipe is gaining popularity due to its contemporary aesthetic appeal and efficiency. Architects often leave this pipe exposed due to its attractive, clean appearance. It is often painted to blend into the ceiling but can be highlighted against the surrounding background.

Get a Quote Today
United Team Mechanical quality

Our HVAC Spiral Ductwork

Spiral pipe made its debut in 1956, after founders Erling Jensen and Leif Andresen spent years inventing a more economical mode of transporting air. Although the technology was new, it quickly gained traction worldwide. By 1970, the demand was so high they opened a location in the United States, originally intended to only be a sales office. The business only exponentially increased, soon they were building the spiral pipe machines here in the United States.

Our spiral ductwork is made on one of these spiral pipe machines. The machine uses a smaller width slit stock coil of metal and shapes a continuous interlocking lateral seam, forming a spiral pattern pipe.

Quality Suppliers

United Team Mechanical’s round spiral duct, longitudinal seam round duct, and fittings are built to meet the industry guidelines:

  • ASTM A653-96 Galvanized G90 Steel
  • SMACNA compliant
  • SPIDA compliant
Icon usa large | United Team Mechanical
HVAC Fabrication and Manufacturing

Spiral Ductwork Options

Our spiral ductwork is held together either by an interlocking standard lateral seam, spaced on 5″ centers. The regular spiral duct does not have the corrugated stiffening beads, but for heavy application we do have the capability to add these corrugation beads. We offer a variety of options to meet whatever your needs might be, including double-wall.

Pipe Diameter

  • 4″ – 24″ in every nominal increment
  • 24″ – 56″ in 2″ increments
  • 60″

Metal Type

  • Galvanized Steel (G-90)
  • Aluminum (.032 & .040)
  • Paint Lock* (24ga & 22ga)
  • Stainless Steel* (24ga)
  • PVS*

*only select gauges are available with this type of metal.

Pipe Length

  • Any size from 12″ – 240″ (standard length is 120″.)

Metal Gauge

  • 18
  • 20
  • 22
  • 24
  • 26

Serving These Industries


Research, Technology

Commercial, Office

Higher Education

Advantages of Spiral Ductwork

If space is not an issue and efficiency and aesthetics are a priority, then spiral ductwork could be your solution.

Lower Fabrication Cost

According to SMACNA duct design manual, spiral is 60% the cost of rectangular duct.

Superior Aesthetics

Architects typically prefer round duct in exposed ceiling applications for a couple of reasons. 1) The spiral ductwork paints and finishes very clean. 2) Spiral pipe/flat oval is easier to paint and finish than the alternative square duct.


Countless options for size, style, gauge, double-wall (which consists of an inner perforated metal surrounded first by insulation and then finished by sleeving it into a typical spiral pipe jacketing), material type and finish are available for spiral duct.


Not only does round duct excel in a commercial HVAC application but for many other applications as well. Consider using round duct for dust collection, particulate ventilation, industrial, mining projects.

More Efficient HVAC System

The surface area of spiral is much less than rectangular, which translates to less air friction and a more efficient system. (i.e. a 12″x12″ duct has a stretch-out of 48″ which equates to a 13.1″ round duct or a 41″ stretch – a savings of nearly 15%).

Faster Installation

Traditionally rectangular ductwork is built and assembled in 5′ sections, spiral, however, is typically built and installed in 10′ sections.

Lower Installation Cost

Spiral requires fewer connections than rectangular ductwork, which lowers the margin for errors on properly sealing the joints – not to mention the time and energy savings.

Less Air Loss

Not only does spiral ductwork require less transverse duct connections, but spiral has no longitudinal connections. At best, it has been difficult to achieve less than a 5% airflow loss with rectangular. Spiral averages a 1-2% air loss. As building efficiency has become an important goal – spiral pipe can reduce waste drastically.

Less Noise Pollution

Spiral ductwork absorbs the noise of the equipment far better than rectangular ductwork. Rectangular ductwork tends to reverberate sound throughout the system.

Frequently Asked Questions

How do I connect round ductwork together?

There are 4 different methods to join round ductwork together. The most simple way is a slip/coupler type fitting, typically used on sizes 4″-24″. Anything over 24″ is usually made with Duraflange rings. Special applications (dust collection, material movement, etc.) will require a vanstone/angle iron ring connection or when installing grease duct it must be welded together.

How do you install slip joint spiral pipe?

In most circumstances, spiral is relatively easy to install compared to rectangular. The first step is to order your material according to the specifications, layout your grille or destination, and then install your hanger strap. Finish installing by making the connection (start with the pipe kicked and slowly lower it while tapping the pipe), install the hanger strap, put to correct among of screws in the joint (spacing is ~6-8″ apart), finish by sealing the joint.

Why use exposed spiral ductwork?

It all boils down to aesthetics. Architects seem to be gravitating toward the industrial look, and for the first time our work is being showcased because until recently most ductwork has been concealed above ceilings and walls. More specifically, spiral or flat oval duct (squished spiral pipe) is the choice for exposed ductwork as it is more visually appealing than rectangular.

What are spiral duct fittings?

Although the spiral pipe is relatively easy to make large quantites of linear feet, the fittings are a much more labor intensive process. All ductwork requires a variation of elbows, reducers, transitions, taps, tee bodies, etc. to properly distribute the air.

How are spiral duct fittings made?

The whole process begins with a flat sheet of metal that is cut to proper size, dimension, and shape. Next it goes through a variety of processes to roll, shape the edges and join the pieces together.

What is double wall spiral duct?

Double-wall duct is constructed of perforated inner shell, insulation, nosing, and an outer shell (perforation is 3/32″ diameter, 23% open area with thermal conductivity is .27 @ 75º – based on 1″ insulation). Double-wall requires no external duct wrap as there is insulation sandwiched between the inner and outer wall of the duct.

Cta icon | United Team Mechanical

Let’s Get Started on Your Next Project

We are Utah’s premier HVAC manufacturer, we take great pride in our work, let us know how we can help you with your next project.

Get Started Today