Tube Expansion-- Taper or Parallel Pin Roller

[WBH]

What is the difference in the tooling for taper rolling and parallel pin rolling for expansion of heat exchanger tubes (ie. 16 gauge ¾” ss tubes). Does anyone have any photo references of each? Can you visually tell the difference between a taper or parallel pin rolling tools?

I am interested in the advantages of each process and the ability to visually recognize which process (tooling) is being performed.

thanks