PROCESS FOR CONTROLLING SNOUT ZINC VAPOR IN A HOT DIP ZINC BASED COATING ON A FERROUS BASE METAL STRIP

摘要

PROCESS FOR CONTROLLING SNOUT ZINC VAPOR IN A HOT DIP ZINC BASED COATING ON A FERROUS BASE METAL STRIP A process for suppressing zinc vapor in the snout of a continuous line for hot dip coating one side or both sides of a ferrous base metal strip with a molten zinc or zinc based alloy by maintaining the atmosphere within the snout to include about 1-8% hydrogen by volume and about 300 ppm to 4500 ppm water vapor with the balance being one or more inert gases, such as nitrogen. The atmosphere has a hydrogen/water vapor ratio of at least 4 to 1, or higher. This atmosphere is oxidizing to zinc vapor but non oxidizing to the ferrous strip.