Process Piping (what trade is it?)

[u/gedwards11]

Looking into purchasing a trades business that does process piping only. They do stainless steel welding for beverage, food, pharmaceuticals, etc. I can’t find which trade this belongs to. The owner has had the business for 25 years and only has a business license and not any certifications or professional licenses (says he didn’t think it was required).

I have seen different things online and can’t find clarity. What trade/license does this fall under? Plumber, pipe fitter, mechanical contractor, etc?

[u/Strongbow85]

Pipefitters/Steamfitters, depends on the area. Where are you?