How are hangers attached to duct?

• A. With adhesives
• B. With pop rivets
• C. With welding
• D. With sheet-metal screws

Answer: (D)

Hangers are attached to duct with sheet-metal screws. The duct is made of thin sheet metal, so self-tapping screws bite directly into the metal to create a secure, removable connection for the hanger strap or bracket. This method is quick, field-friendly, and avoids heat distortion or the need for access on both sides, which welding or riveting would require. Adhesives wouldn’t provide the necessary strength or reliability under vibration and load. Pop rivets are possible in some fabrication scenarios, but sheet-metal screws offer a practical, durable, and serviceable attachment for hangers.