I have flexible ducting for my heat and air and my house is about 11 years old. All of the tees and branches from the main duct lines are connected by duct tape, which is now starting to give and come apart. There seems to be metal or aluminum tubes inside the duct at the connections, but the only thing holding them together is the falling apart duct tape.
What can I do to make this a better joint with less worry of heating/cooling my non living space attic, other than adding more duct tape?
Thanks.

Proper flex duct connection is simple. For a deluxe job you use mastic on the metal connector and place the flex inner liner over it. Then you use very large cable ties designed for this purpose and a tension tool to tighten. Then you pull the ends of the flex over the joint and tape.

Many times people do not use the mastic because it can be messy to work with but it does provide a much better seal.

All of these materials and tools are available from a supply house or possibly Home Depot

So I need to pull back the outer shielding of the duct, attach the liner over the metal, then install cable ties. After that, pull the outer shielding over the ties and tape with duct tape? (This is not using the mastic, not sure if it has been used or not).
Are the cable ties just regular ties that are large enough for this application?
Thanks.

The cable ties are wider and much longer