What type of joints and seams in ducts are continuously welded and exempt from sealing requirements?

Continuously welded joints and seams in ducts are specifically designed to provide a strong, airtight seal without the need for additional sealing requirements. The welding process creates a permanent bond between the pieces of metal, resulting in a seamless connection that minimizes the potential for leaks, which is critical for maintaining system efficiency and performance.

In mechanical systems, minimizing air leakage helps reduce energy costs and improve indoor air quality. As such, continuously welded joints are recognized under regulations as being sufficient to eliminate the need for further sealing methods. This exemption reflects confidence in the durability and effectiveness of the welding process in ensuring a tight seal, which is essential in HVAC applications.

Other types of joints, such as stitched, temporary, or loosely connected joints, do not provide the same level of assurance in terms of air tightness and structural integrity, hence they are subject to additional sealing requirements to prevent leaks and ensure system efficiency.