What is the requirement for mechanical fasteners used to support commercial grease ducts?

Mechanical fasteners used to support commercial grease ducts must not penetrate duct walls. This requirement is crucial because penetration can create points of failure in the duct integrity and lead to leaks or contamination from the processed grease. The fasteners must provide structural support while ensuring the grease duct remains sealed and functional in compliance with safety and health standards.

In the installation of grease ducts, it is vital to maintain the integrity of the duct system. If the fasteners were to penetrate the walls of the duct, it could allow smoke, grease, and other contaminants to escape, which is against the safety practices and can lead to fire hazards. Thus, the precaution of avoiding any penetration is essential for preventing cross-contamination of air and for maintaining the duct's flame and grease resistance properties.