I am designing an out building that has three walls and the fourth wall is open to the air. This building will have small tanks that will have welding gases stored. this will be a small building, 10x14. 9 foot ceiling. i am trying to determine the hazardous classification. These tanks will only be stored at this location, not used or filled. this leads me to believe that there will not be any gases outside of the tanks that would warrant a classification for the building. Any ideas to support or not support? There will not be any fans or ventilation of any sort; only light fixtures in the building.