Welcome mktarby!!!
ASME Intl. has got a webpage that lets you search for companies that perform the code work you're looking for... Here's the page:
http://cstools.asme.org/holdersearch/index.cfm
Do a search on all certificates or any of the ones listed, and in whatever state or city you're looking for, then you'll be directed to a list of companies from all over the planet that holds certificates to perform Boiler/Pressure Vessel code work according to ASME...
You click on a company from the list, then wait for a smaller window to appear, and inside will be the company's address, what certificates they have but, not much else though... Good luck, and I hope this helps!!!
Respectfully,
SSBN727 Run Silent... Run Deep!!!