Ceiling fan mounting, old home, worried I did it wrong
That support is probably an old gas line (pre electricity) I say this because of the length you described. If it was shorter and anchored in the box itself or just above the box it would be called a hickey. Years back this hickey was a normal way to support heavy fixtures. And as long as it cannot come down your fan will stay up there. As far as other comments this is not knob and tube. Because it is in conduit, since it is in conduit I would consider pulling some new thhn wiring. Now for the last part of your question, current code calls for listed boxes but on older homes I have used the same hardware you have and there were no problems that pipe is probably stronger than a listed box.