How Are Spiral Ducts Assembled Together?

Spiral Flexible Air Ducting and accessories; elbows, reducers, etc. slide together, just like the plumber's copper pipe. However, although plumbing fittings usually slide on the pipe, piping fittings slide inside the spiral pipe. Therefore, the duct bending will be slightly smaller than the nominal size. For example, a 100mm elbow will actually have a diameter of about 98mm, allowing it to slide inside a tube that is actually 100mm.

All accessories, except that the tube itself is male (that is, slides into the inside), nothing more. The outlets on the machine (fans, canopies, dryers, etc.) are also usually male. With this in mind, you can understand that, for example, a 125mm bend cannot directly match the 125mm outlet on the machine. They are the same size.

If you want to connect the two accessories directly or connect the accessories to the machine, you can use the female connector. In practical terms, it is a very short tube. The male connector is of course used to connect the pipe sections. Female connectors will not do this because they are the same size as the test tube.

Flexible Duct Hose 

Flexible Duct Hose is very similar to spiral tubes because they will slip through the accessories. In most cases, although it may tighten, it will also slip on the spiral tube, in which case you can insert the externally threaded fitting into the tube before fixing the flexible tube.

Once slipped together, the joints are usually secured with rivets or self-tapping screws, although most installers today prefer to use self-drilling screws because this allows them to complete their work faster. Then apply sealant around the connection. After curing, the sealant will be very effective and lead to a more efficient system. Alternatively, the sealant can be applied to the tube before being fixed together. This has the advantage of being neat and easy to use, but if the pipe needs to be disassembled, because the sealant itself is like a very tough glue, it may cause problems. The tape is another simple and effective method of sealing, although for many years it will eventually dry out and become loose. Please also note that self-sealing duct fittings are also available; they come with EPDM rubber seals, and although they are slightly more expensive, they do not require sealants or tape. Hose clamps are used to secure flexible pipes.

What is the best way to cut the spiral tube?

Depending on your requirements, you may get various answers, but (assuming you do not have the ability to use Lindab SR cutting machine, of course, you are unlikely to use it), we found that the best way is to use a thin metal plate suitable for cutting Blade.

Place the pipe on a clean surface. Very good on the floor. Mark the air duct at various points around the air duct, for example, if you want to measure a pipe with a length of 1 m from 1 m at the end and place a mark. Then, you can make further marks around the air duct according to the diameter of the air duct, separated by 50-150mm. It is important to always mark. If you do not do this, you will most likely find yourself disconnected. When you return to the starting point, you may find yourself "missing" and must turn sharply to reach the initial cutting point. Drill a hole of suitable size (8-9 mm) to allow you to insert the jigsaw blade and slowly and carefully cut around the air duct according to the previous mark.

It is strongly recommended that you wear protective glasses when using the jigsaw. Chips usually fly out, but it is not uncommon to fly up to the face. You may also want to use a protective ear-worn device because this method is very noisy.

Another simple and clean method (although quite slow) is to use hand punching (see picture below). These are cheap and made by Draper, Monodex, and Sealey. Like a jigsaw, you need to drill a hole to get started, and you may need to use a hacksaw on the seam, but if you only make some cuts, they are ideal.

Although it is certainly possible to use an angle grinder with a thin metal-cutting disk, it is generally not recommended. This is a fairly rough, dangerous and dirty method that may make the edges of the pipe very sharp. If you do use an angle grinder, you must wear protective glasses, preferably wearing safety gloves.

Finally, it is, of course, possible to use a hacksaw with a smaller diameter. However, it can be slow, laborious, and sometimes frustrating.