This is my first post. I am the job super for a new restaurant. My past experience is with residential construction. We hired a hood sub contractor that i am having great difficulty with. He is using plane carbon steel duct work to extract steam from a hood for a kettle to boil bagels in, and a hood for a dishwasher. i can't see this lasting too long. It is the same type of material that he used for the grease hoods. I would assume it is fine for grease hood ducts but to extract steam? I don't see this lasting very long. He insists its fine and he insists that because in his contract he did not specify that he was going to use stainless he does not have to give us stainless. We are governed by international mechanical code. Will this pass inspection? I read the code book and found code # 506.2 about corrosion. It states ducts exposed to outside atmosphere or subject to a corrosive environment shall be protected against corrosion in an approved manner. As far as I see it steam is a corrosive environment. He insists this code is only for outside duct work. Is he right? Are there any published standards or codes that say you can't use raw steel for this application? Any help would be appreciated .