What is the minimum circular duct overlap?

What is the minimum circular duct overlap?

• A. 100 mm
• B. 50 mm
• C. 150 mm
• D. 200 mm

Answer: (A)

When circular duct sections are joined, there must be enough overlap to seat the duct properly into the connection and to accommodate the sealant or tape and the fasteners. This overlap area provides the surface and room needed to create a tight, airtight joint that can withstand the operating pressure and any vibration in the system. If the overlap is too short, there isn’t enough room to apply the seal and secure the joint, which leads to leaks and a weaker connection. A longer overlap isn’t necessary for function and can waste material or cause fit issues in confined spaces, so the minimum amount is the length that still allows a reliable seal and secure fastening.

When circular duct sections are joined, there must be enough overlap to seat the duct properly into the connection and to accommodate the sealant or tape and the fasteners. This overlap area provides the surface and room needed to create a tight, airtight joint that can withstand the operating pressure and any vibration in the system. If the overlap is too short, there isn’t enough room to apply the seal and secure the joint, which leads to leaks and a weaker connection. A longer overlap isn’t necessary for function and can waste material or cause fit issues in confined spaces, so the minimum amount is the length that still allows a reliable seal and secure fastening.