What type of connectors are used to secure sections of the trunk line in sheet metal duct installations?

The correct choice refers to S connectors and drive clips as the type of connectors used to secure sections of the trunk line in sheet metal duct installations. S connectors are specifically designed to create a tight, secure connection between different sections of ducting, while drive clips are utilized to further secure these connections to prevent any potential airflow leaks and ensure structural integrity.

In sheet metal duct systems, maintaining a well-sealed and properly connected trunk line is essential for efficient airflow and system performance. The use of S connectors offers flexibility in installation, accommodating changes in direction and alignment, which can be important in ensuring that ducts fit within the constraints of a building layout. Drive clips enhance the stability of these connections, providing additional support and minimizing the risk of disconnections over time due to vibrations or thermal expansion.

The other options, such as flex connectors, welded joints, and slip joints, serve different purposes. Flex connectors are typically used when a degree of flexibility is required, such as in areas that experience movement or vibration. Welded joints provide strong and permanent connections, but they are not commonly used for routine duct installations due to the complexity and need for specialized equipment. Slip joints allow for easy assembly and disassembly, which is beneficial in certain situations, but do not offer