I have little experience with mig welding but I think I would like to attempt to seal up my new exhaust with some welds since the clamps are not really sealing. I have a Hobart Handler 140 it is a 115v 25 to 140 amp mig welder I bought it awhile back so I cn finally start learning and have only had half asses success. It came with a spool of .30 flux cored wire and I am having a heck of a time laying a good weld. From what the wire spool states is says I dont need shielding gas since it is flux cored but I am having my doubts. I seem to always get spattered and spotty welds no matter the voltages or wire speed combo. Do I need shielding gas irreguardless of flux cored or wire thickness? Also what wire thickness I should be looking to use on the exhaust pipe and what shielding gas? Are there smaller tanks of gas like a half height or quarter height? where do I buy the recommended gas at? I would love to learn how to get better but since I dont even know where to buy the gas at I think I should be asking for help lol.