1. Welded Tee: A tee pipe fitting that is welded to the connecting pipe components.

2. Socket tee: a tee pipe fitting where the connecting pipe is inserted into each end of the tee and then welded or brazed.

3. Socket Tee: A type of tee where the ends are socket joints, which are tightened after the pipe fitting is inserted.

4. Threaded Tee: A type of tee pipe fitting connected by threads.