To use T19 tips on the FX-8801, you need to use the B5122 tip enclosure for it. The process for installing the tip is the same as that of the T18 tip. Place the T19 tip over the ceramic heater, place the B5122 enclosure with nut over the tip and then screw the nut onto the metal threads of the nipple to secure it in place. Be sure not to cross-thread the nut to the metal threads of the nipple and be sure the iron is not powered.