If a duct is welded, what is required regarding sealant?

When a duct is welded, it creates a continuous and airtight joint that inherently provides ample sealing between sections. This airtight feature means that additional sealant is not necessary to maintain the integrity of the duct system. The welding process itself produces a durable bond that reduces the likelihood of air leaks, thus ensuring the efficient operation of the system. Consequently, because welded joints do not require further sealing measures to meet performance standards, no sealant is required for these types of connections.