I use a propane radiant heater - can still burn the pipe but a torch directs too much heat to too small of an area and is too easy to burn the pipe. Even the Greenlee heaters can burn the pipe if you aren't paying close enough attention though.We always used a torch at work because most of the times we are running it there's no power on the job site yet. We have the greenlee heaters for big pipe something like that we get a generator or plug in at the temporary. But it's too time consuming. With a torch u can turn it to right before the gas shuts off and have an invisible flame that works okay but everyone burns it every once in a while.