In duct systems, traverse joints are typically sealed according to standard requirements.

• A. Traverse joints Class C
• B. Flange joints Class A
• C. Butt joints Class B
• D. Seam joints Class D

Answer: (A)

Traverse joints in ductwork are designed to pass ducts through barriers or around obstacles, so they must seal effectively while still allowing for some movement and misalignment that can occur in the field. Sealing these joints to a mid-level standard (Class C) provides reliable airtight control without the added complexity and cost of the most stringent level. It strikes a practical balance for typical installations, ensuring sufficient leakage control under normal operating conditions, while remaining feasible to install and maintain. In comparison, tighter levels (like Class A) are reserved for critical applications with very strict leakage limits, whereas other joint types have requirements tied to their specific construction and needs, rather than a one-size-fits-all approach.