I've found that people are using pipe nipples for the air intake. I went to home depot yesterday to get them. I don't think people are using the galvanized so I bought the 'black steel' nipples. Are those safe or do we need to buy something else. I know they are on the outside of the drum but the air is going through them so I didn't want the galvanized because I hear so many people talk about the harmful vapors when it gets to a certain temperature.