Venting
Venting is a fundamental safety and quality requirement in the galvanizing process for any hollow structure, including tubes, pipes, or enclosed fabrications.
Purpose in Galvanizing
Venting refers to providing adequate openings and orifices that allow air and gases to escape during immersion into the molten zinc bath (hot dip galvanizing), which is typically heated to around approx. 450∘C. This serves two crucial functions:
- Safety (Pressure Relief): When a sealed or inadequately vented piece is submerged, any trapped air or residual pickling liquids inside the pipe rapidly vaporize due to the extreme heat. If this superheated vapor cannot be released, the pressure can cause the pipe to rupture violently, posing a severe risk to personnel and equipment.
- Quality (Complete Coating): Proper venting allows for the complete displacement of air by the molten zinc. Without it, air pockets can form, resulting in uncoated areas within the pipe's interior. These flaws immediately compromise the pipe’s long-term corrosion protection.
Therefore, meticulous planning of vent holes and drainage points is mandatory under galvanizing standards to ensure a safe, uniform, and high-quality zinc coating.