Found in my stash of chemicals a bottle of EXRust, from Kano labs, where I buy my Kroil penetrant (best stuff out there). I had not used this before, so hoped for the best, and got it. diluted it two parts of water to one EXRUST. submerged the rusty end of the pipe in an elbow of 1.5" PVC pipe, and then the whole thing in an empty ice cream carton (for safety in case of spill) Went to dinner, came back and metal is clean, ready for rinse and spray paint. I am very pleased, worked very well, and no scrubbing needed. I'll treat and paint to keep it from rusting again. Thanks to earlier post suggesting it in some kind of container. I'm lucky in that it was only affecting the bottom 2 or 3 inches.
