Gasketing is an essential measure used to create tight, durable seals between joint surfaces. In HVAC systems, this directly combats the invisible thief: air leakage. Without proper gasketing, improperly sealed ductwork can leak up to 30% of air, resulting in waste and forcing the system to work harder. Over time, this can lead to system failure and costly repairs.

Prioritizing proper gasket application is not only best practice but also crucial for maximizing energy efficiency, extending system lifespan, and meeting building codes and standards.

What Gasket Options Does Ductmate Offer?

DM 440 Butyl Gasket Tape & Patches

DM 440™ Butyl Gasket Tape is the preferred gasket for the Ductmate ‘25’/’35’/’45’® flange connector systems. This tape has the widest range of application temperatures of any material on the market, ensuring a positive seal and ease of application under extreme conditions and is also suitable for use with other rectangular flange systems that require a gasket.  It is LEED-compliant, USDA-acceptable, and meets FDA requirements, and is formulated with an EPA-registered biocide package that prevents the growth of mold, mildew, and fungus.

For the ‘25’ and ‘35’ systems, we suggest using a 5/8” wide 440 gasket, while a 1” wide gasket is recommended for the ‘45’ system. Optional 3” x 2” 440 corner patches are also available to help eliminate inconsistent or recurring gasketing problems at the corners.

Neoprene Gasket Tape

Neoprene Gasket Tape is a synthetic, closed-cell, and rubber-based duct sealing tape ideal for ensuring a firm, reliable, and long-lasting airtight seal in ductwork.

Its pressure-sensitive adhesive backing makes installation quick and easy. The durability of neoprene foam makes it easy to remove from ductwork without leaving a sticky residue or falling apart. This makes disassembling ducts for periodic cleaning or maintenance easier, allowing for quick, straightforward application of new tape to reseal the connection.

For applications using the DM ‘45’ system, a 1” wide neoprene gasket is required, while a 5/8” wide gasket is used for the ‘25’ and ‘35’ systems.

Sticky Tape

Specifically formulated for use in TDC & TDF roll-formed flange systems, our Sticky Tape is a high-quality general-use tape developed for the industry as a sealant, moisture, and dust barrier. It is non-hardening and has excellent adhesion to most dry metal surfaces.

Installing Gasket During Assembly

Rectangular Slide-On Flange Systems Standard Practices

When applying a gasket to slide-on flange connector systems, start by applying it halfway between the duct corners, then center it on the angle.

As you approach the duct corner, position the gasket in an arc to cover the three critical points. Please note that some gasket will protrude into the airstream.

Press the gasket firmly into contact with the raw edge of the duct corner and the Ductmate corner assembly. Apply the gasket completely around the Ductmate frame to the beginning point. Where the gasket meets, overlap it for approximately 3/8”.

On the opposing frame, apply 440 gaskets only to the corners, approximately 3” per corner, and make sure to cover the same three critical points as before. Alternatively, the DM 440 corner patches can help eliminate inconsistent or recurring gasketing problems at the corners during this step.

Carefully align mating frames before they touch, as DM 440 adheres on contact. A drift pin can be used to correct any misalignment.

Removable or Breakaway Connections

Begin by wiping the face of the flanges and corners with a dry cloth where the gasket and sealant will be applied.

Apply a water-based sealant to all eight corners of the connection, ensuring it covers the gaps between the corner and the duct wall. Allow the sealant to fully dry before applying the gasket.

Apply neoprene gasket around the perimeter of one duct section of the connection. Start gasketing halfway between corners, favoring the outside edge of the flange. Apply it in an arc at all four corners, making sure to cover the three critical points.

Finally, as you approach the start, press the end of the gasket tightly against the starting point.

TDC & TDF Roll-Formed Flange Connections

Another popular type of ductwork, in addition to our slide-on flange systems, is the TDC & TDC roll-formed flange. When applying gasket, similar application practices can be used in accordance with slide-on flange systems; the only difference is that we recommend our Sticky Tape, formulated specifically for this system type.

Ready to Buy?

Ductmate products are available at over 350 locations across the US as part of a selective distribution network.  Use the Ductmate distributor locator map to find a distributor near you.

Outside the US? Check out our international distributor list.  For detailed information on product availability, lead times, or other international sales requests, please email ductmate@ductmate.com.