Installation of Duct Reinforcement

There are three components in an aluminum reinforcement system: the aluminum reinforcement bar, discs, and mounting screws. The bar is inserted vertically in combination with the reinforcing discs inside the duct. Four discs total are installed for every bar, two on the inside of the duct and two on the outside surface of the duct. The self-threading mounting screws are inserted from the top of the outside disc to the reinforcement bar in combination with the inside disc. As shown:

Duct Reinforcement Joints as required

In case of multiple reinforcement bars as shown above, the distance between bars is 50% of the step Distance as indicated on the reinforcement chart. When an horizontal bar is also required, the bars shall be tied together at the point of intersection with cable ties.

Aluminum Flanges

IM suggests two different types of flanging systems for joining duct segments together.

Invisible Flange

Determination of the type used is based on the application. The one generally used is the invisible flange, where the “H” shaped bayonet in PVC joining the two segments together is hidden (invisible) inside the two aluminum profiles. Two of the main features of the invisible flange is the easy installation in limited access areas and when the duct is in-view and aesthetics are a prime consideration. It provides a tight joint without the use of adhesive or gasket. The Teeth Connector is a very economical alternative only in small and low pressure ductwork applications. Small is defined as maximum size of any duct side to 500mm and maximum pressure of 500 Pascal. It is an aluminum plate with prone points (teeth) in each end.

Teeth Connector Flange

Aluminum tape is applied to the ends of the two duct segments followed by a continuous bead of Silicone around the end of only one segment. Then, the two duct segments are joined together and a Tooth Connector for duct sides up to 300mm is pressed in the middle of all four sides of the duct and centered over the seams. For ducts between 300 and 500mm, two Teeth Connectors evenly spaced are applied. Aluminum tape is then wrapped around the joint of the two ducts which consequently covers the Teeth Connectors and the seams.