Intrument Air Line SS or CS

Gents,

What is your take on the I/A line to be SS or CS? I have done projects where they have used both types of material.

Like you I have used both, but my experience because stainless steel is expensive, plus is a "pain" to thread, everyone normally uses carbon steel that is hot dipped galvanized and threaded, it is cheaper/easier way to go in industrial use. Pharmaceutical use is different, in clean room environments, stainless is preferred.

I'd like to make a clarification to JOP's comment, I agree with him in general but you have to be careful with chlorides and stainless steel. Trying to use common 316/316L in or around chlorine can lead to "chloride stress cracking", so be sure you're following an approved piping material spec(by a material engineer) for the commodity that is being piped up or exposed to.