That is not pipe, but rather Acme threaded rod. It is used by machinists to make jigs and fixtures. You can get it at Fastenal type stores. There are nuts and washers that go with it so all the shelves were supported with nuts. Hope this helps!
What about the other shelf supports screwed into the wall? Love the look.
That is just little piece of angle iron that I drill and countersink.
Mast & Co. Builders
hornet22
Mast & Co. Builders