Which type of joint is most commonly used in sheet metal ductwork?

The most commonly used joint in sheet metal ductwork is the slip joint. Slip joints are designed to connect two pieces of ductwork in a way that allows for thermal expansion and contraction. This is particularly important in HVAC systems where the temperature changes can cause the metal to expand or shrink. Slip joints are simple to install, requiring less time and specialized equipment than other joint types, making them a cost-effective option for connecting ducts.

When installed correctly, slip joints provide a secure and airtight seal that helps maintain system efficiency by preventing air leaks. Their design allows one piece of duct to fit into another, facilitating ease of assembly and disassembly for maintenance or adjustments. This flexibility is crucial in HVAC applications where duct modifications may be needed over time.

Flanged joints, while also used in ductwork, typically require more space and additional hardware to secure the flanges, making them less suitable for most typical sheet metal applications compared to slip joints. Rivet joints, although strong, are less common in modern ductwork due to the need for additional tools and labor. Welded joints provide a very strong connection but are generally more labor-intensive and require skilled labor to execute properly, making them less common for routine duct connections.