Removing rust can be a big headache but not if you use your brain a little and some electricity.
I used a 12V .5A power supply and attached the negative end to the pipe wrench and the positive end to a old piece of steel remesh. Both pipe wrench and remesh were put in a bucket of water that had some baking soda. After a few hours of bubbling I removed the pipe wrench and let it sit for a hour in a vinegar bath.