Making the pipe pieces - their origin is at the center of the scene, not the center of the object

I did not know I had this problem until I got to the place where I already made the pipe piece and now it's time to make the pipe hanger. 

But the origin of the object is nowhere near the object, I think it's at the center of the scene.

How can I set it to the right place so I can use the mirror modifier to make the pipe hanger?