Can I Renew My Non-B Visa in Thailand or Do I Need to Return to the USA?

we are done. Good Luck to the O/P.. Whether you're going to get an extension inside the country (which I would say you're not) or go back to your country to get a new year-long, Non-B (where you bounce out and back in every 90 days) is between you and the company you work for.

First article inspection huh? Just a guess. U need a work permit also and it is good for only one location. Company must be in Thailand. I know, I lost the opportunity to make 300,000 baht a month many times.

The question is now are you working and living in Thailand or are you visiting Thailand multiple times a year for less then 15 days to conduct your inspections?

You can read the difference and length of stay requirement at the website of the Thai Embassy in Washington DC. For a Non Immigrant B visa to conduct business you must apply in your home country.