I have a 1.5 inch (?) galvanized waste line that has a galvanized threaded insert that I wish to remove and place a pvc trap and clean out for a washing machine. How do you get the plug out of the tee? I have tried pipe wrenches, but I can’t seem to get the cap to move. I am a little unsure of appling heat since this is a drain line … should I be worried about heating a pipe that may have sewer gases in it?
The line should not have sewer gasses in it if it is properly trapped and vented. If there is no trap, it must be vented, so the risk of an explosion (your main concern) should be non-existant. In any case, the quickest and best way to get into the drain line is to cut out the fitting and install drainpipe with hubless connectors.