All flux core/nr211 wire has a 70,000 tensile strenght. Pre heating has nothing to do with penatration. Pre heating and post heating is only for control of the cooling process. Yes you can use a 110v welder, but it will not be the proper way to do it. Now for structural steel we use nr232 because it is a lohy wire same as 7018 stick. The 180 will handle the job, but you need to ask yourself, "can the operator/you handle it?".