Duct reinforcement: ventilation duct large side length ≥ 650mm, length ≥ 1250mm plus reinforcement, the use of materials and flanges the same material.

        Corrosion: ordinary steel wind pipe must brush before rusting rust again, inside and outside before installing anti-rust brush again. Support, anti-corrosion hanger should be intact. Duct flange pressure nozzle first spray paint. Corrosion should be ≥ 5 ℃, ≤ 80% humidity environment should be carried out before construction, degreasing, rust treatment.