From the Technical Resources Department. Update to the SMACNA HVAC Duct Construction Standards, Metal and Flexible, Fourth Edition, Figure 2-18 Corner Closures - Flanges.

This technical resources bulletin updates the language for corner fastening requirements used in conjunction with the T-25a and T-25b flanged transverse joint assembly.
TRB #01-25 Figure 2-18 Corner Closures - FlangesNov 24, 2025 — Member Update
Jul 1, 2026 - Modules focus on sections related to Duct Classifications, Critical Loads, and Panel Gage & Stiffener Selection
Jul 1, 2026 - The current Acting Secretary has led the Department since April, and SMACNA looks forward to continuing its relationship with DOL’s leadership to expand registered apprenticeship opportunities and enhance related workforce policies.
Jul 1, 2026 - Scholarship Program identifies and recognizes academically talented youth and potential future leaders within the SMACNA extended family to provide opportunities to further their education and develop their talents.