What is an acceptable method for fastening round metallic ducts?

The correct answer highlights that mechanical fastening with screws or rivets is an acceptable method for fastening round metallic ducts. This method is widely accepted in the industry because it provides a strong, durable connection that can accommodate the expansion and contraction of metal due to temperature fluctuations. The use of screws or rivets allows for a secure attachment that can resist the airflow pressure typically encountered within duct systems.

Moreover, mechanical fasteners are advantageous because they are easily accessible for installation and future maintenance or adjustments. They enable quick assembly, which is essential in the construction process, ensuring that ducts can be reliably connected without specialized skills or equipment required for methods like welding.

In contrast, relying solely on welding may not be practical for all installations due to the need for specialized training, the potential for distortion of metal from heat, and limitations in access to certain areas. Similarly, the use of glue would not provide the structural integrity required for accommodating the pressures in mechanical duct systems and is not a recognized standard for this purpose. In summary, utilizing mechanical fastening through screws or rivets offers a balanced combination of strength, practicality, and industry adherence.