How to Screw 3-Inch Galvanized Duct Pipes Together

Duct sizes can vary depending on the room size.

Galvanized duct pipes like aluminum and stainless steel ducts are used to either bring conditioned air to a room or vent air out. Joining the galvanized duct pipes together is essential to finish a long installation of duct pipes. Properly adhering the two duct pipes together is important to ensure it is an air tight seal. With the proper tools and directions, you can quickly connect two galvanized duct pipes together regardless of size or material of the duct pipes.

Things You'll Need

• Tape measure
• Marker
• Aviation snips
• Drill
• Sheet metal screws
• HVAC foil tape

Instructions

1. Measure the size you must cut the duct pipes before joining the ducts together using the tape measure, then mark them with the marker.

2. Cut the duct pipes to size using the aviation snips. Only cut the duct pipes from the plain end that is not crimped. Duct pipes have a plain end and a crimped end; never cut the crimped end from a duct pipe or you can never join it with another duct pipe.

3. Push one of the duct pipe's plain end into the other pipe's crimped end. Hold both pipes together, keeping both of them straight.

4. Screw in sheet metal screws with the drill into the duct pipes to secure them together. Place a screw every three inches around the duct pipe to secure them to one another.

5. Wrap the joint of the pipes with the HVAC foil tape. Remove the backing of the tape and wrap it around so it overlaps one inch over each side of the duct pipes and the sheet metal screws. The HVAC foil tape will ensure no air leaks occur at the joint.

References

• Alpine Home Air Products: Ductwork
• Nordfab Ducting: Galvanized Ductwork and Pipe
• Handy American: Duct and Pipe Insulation