Manufacturer Certification: EU vs. US

Hi! I'm working for a steel structure manufacturing company based in the UK and we are planning on opening a branch in the US. I was now wondering about the different standards that apply in the US for selling high-quality construction materials. In the EU it's the EN 1090 ([url]www.tuv.com/en1090[/url] --> there is no page on wikipedia, sorry) but which standards are needed for the US? I found this list on wikipedia [url]http://en.wikipedia.org/wiki/List_of_welding_codes#American_Welding_Society_standards[/url] , but as there are quite a few standards I don't know which apply.
It would be great if you could hepl me. Thank you!!