The present perfect can be used to express the idea that one has experience in a particular area, even if one is not working in that area at present.
2014--present: lion tamer
2010-2014: underwater welder
In 2016, you could say:
I have worked in underwater welding for years.
You do have that experience. But the present perfect does not clearly indicate that you are an underwater welder in your present job.
To convey the idea that you are still an underwater welder now:
2010-present: underwater welder
you would say:
I have been working in underwater welding for years.