The insulation is rigid foam, (like Great Stuff) not fiberglass, so I can't just pull it back.
The pipe is sort of "cast into" the foam insulation. So, I can't get to the other end of the pipe without cutting all that away. There isn't even a whole heck of a lot of room around the pipe before hitting the outside sheet metal cover of the tank either.
When I was talking on the phone last night with Doax, he mentioned that the size of the pipe seemed to measure up close to the outside of 3/4 NPT pipe. But I wasn't thinking about just a nipple threaded in there at the time.
I DID scrub up the cut pipes. While they had quite a bit of corrosion on them, and I thought they were copper.....
They did have a little bit of a gold tint to them. I held up some copper pipe that I quickly polished up to compare it with. Sure enough, much more gold colored by comparison. Here's a photo.
My digital still camera tends to exaggerate chromenance (intensity of color). In real life, there isn't such a huge difference in color between these two. With the corrosion on the pipe, it looked very coppery.
Since I had never heard of copper nipples, I never even thought of it!
So, if these ARE just brass nipples, what's next? SHOULD I try just unscrewing them?
What are the odds of the other ends being soldered or otherwise connected in there?