How is Spiral Duct Made?

Have you ever found yourself staring at exposed spiral duct work and wonder how it was made? If your answer was no I guess you can stop reading, but it is a pretty interesting process. If your answer was yes, continue reading to find out.

While spiral duct isn’t something we manufacture at Metalwest, HVAC is a common industry we service. So, why not delve into the process behind one of our serviceable industries?


To discover how spiral duct is made we must first cover the basics, or in other words, the materials.

Galvanized Steel

Galvanized steel is the most common material used for ductwork. Galvanized steel is ideal for ductwork because it is corrosion resistant and can withstand higher temperatures.


Aluminum sheet is used for ductwork because of its high strength and light weight. Lightweight pieces of duct can span longer distances without the need for supports. It is also flexible, which means it can be stretched and bent multiple times, but still hold an airtight seal.

Stainless Steel

Stainless steel ductwork is used more frequently in laboratories due to its sanitary benefits as well as its corrosion resistance to harsh substances. It also has greater strength than aluminum and is abrasion resistant.

The Spiral Duct Process

There are three parts to the spiral duct process. The first starts with the mill and the making of the raw steel (here are some posts on how galvanized, aluminum, and stainless steel are made).

The second part consists of Metalwest receiving coils from the mills and processing them into slit coils. Slit coils are narrower coils cut from a larger master coil (you can read more about it here).

These slit coils are sent to customers per the required specifications and processed into spiral duct, bringing us to the third part of the process.

The Spiral Duct Fabrication Process

Once a customer receives the slit coil it is placed on an uncoiler and sent through a rough leveler to flatten the material. It is then sent through an edge trimmer and formed.

The forming process sends the strip through an inner and outer welding stage that moves it in a circular motion to form a spiral. The edges are welded or pinched together to form the duct piece. It is then cut from the machine at the desired length, inspected, tested, and then sent on be installed.

Here is a video example of the spiral duct process.

The finished spiral duct (in some cases it goes on to be painted) is then installed in commercial buildings such as warehouses, medical facilities, restaurants, schools, etc. So the next time you find yourself staring at exposed ductwork while sipping on a caramel macchiato, you will know how it was made.

For more information about the materials used for spiral duct contact your local sales representative.

Metal Garden Tools

March is a time of year when the snow starts to melt, tulips begin to blossom, and your yard is a dirty mess. Spring cleanup can be the worst part of yard work. You have to deal with leaves everywhere, matted down grass, and, in some cases, pet messes every few feet.

With all these messes around your yard it is likely you will be reaching for a rake, shovel, hand garden tools, and possibly even a lawn mower. Did you know many of these tools commonly use steel?

Let’s take a look at some metal garden tools, shall we?

Metal Garden Tools


Metal lawn rakes, also known as leaf rakes, are generally made from metal or plastic. There are pros and cons to both, but let’s take a look at metal rakes.

Metal is more resilient, but can cost more money than a plastic rake. They feature either a wooden or metal handle as well as a flexible metal rake head. The metal tines on the rake head are fashioned into a fan shape and angle slightly downward to easily grab leaves.

There are a few different types of steel used for metal rakes. You can find rakes made from light gauge aluminum, as well as light gauge galvanized and other types of carbon steel.

Another metal garden tool includes bow rakes. Bow rakes are used for heavier materials than leaves and are great for leveling dirt, sand, mulch, or gravel. The tines are shorter and thicker than the leaf rake, but are also made of metal. A heavy-gauge carbon is typically used for the rake head, but they can have wood, metal, or plastic handles.

Other rakes that use metal include: shrub rakes, thatch rakes, and hand rakes.


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As we mentioned in a previous post, Winter Uses for Steel, shovels are commonly made from steel. Steel provides a durable, long lasting quality to garden tools, which is why it is the ideal material for a garden shovel.

Chances are you have a digging shovel or two in your garage or shed. These kinds of shovels are used for digging, planting, and allow for transplanting small bushes and plants. They are also great for cutting sod and small roots. Digging shovels are most commonly made from a heavy-gauge carbon steel, however you can find them in aluminum as well (typically used for smaller jobs).

Garden trowels and soil scoops are also commonly made from steel. If you plan on potting small plants, spot reseeding, or doing any other minor gardening task, trowels and scoops are the tools to use. Because these are used for lighter tasks, they are also frequently constructed using plastic. However, steel trowels and scoops are more durable and last longer.

Lawn Mowers

After you have raked your lawn and the grass has turned green it is time to trim it. Lawn mowers come in many different sizes depending on the job; you may have a small reel mower, a rotary mower, or even a ride-on mower.

Whichever type of mower you have, it contains metal parts. Major components that are made from metal are the mower pan, handlebar, engine, and blades. Depending on the type of lawn mower, the cover might also be made from metal, but they are also commonly constructed of plastic.