I opened up the wall behind my kitchen sink during a major remodel to find iron nipples in threaded brass fittings. Here is an image with labels:
I removed the iron nipples from both cold water supply tees on the left side. Here's a picture of the condition of the lower-left nipple after removal, which was feeding a brass 1/2" FIPS x 3/8 comp shut off valve that supplied a dishwasher:
I was planning to plug the lower left tee and run both the dishwasher and sink off the top left tee, using a 1/2" FIP x 3/8 comp x 3/8 comp valve, because the lower tee intrudes into the rear frame of the sink base cabinet and would require cutting the cabinet, which I want to avoid.
However, after discovering the brass-to-iron connections I decided to sweat off that lower left tee entirely and replace it with a soldered couple. I wasn't able to remove the iron nipple from the hot supply tee on the upper right so I am going to cut that out and replace it with new brass tee, brass nipple, and valve.
My question is about the remaining cold water supply tee on the top left. Is it reasonable to clean the remains of the corroded iron nipple out of the female threads of the brass tee and install a new brass nipple and fitting, without replacing the tee itself? I'd like this area to be leak-free for the long term.