So I completely broke the bolts holding my muffler. So the weird thing is that the nut is welded to the exhaust flange. Do I just hack the nut off and the rest of the bolt that is threaded to the nut should just fall out, right? I thought about using my angle grinder but sparks and the gas tank nearby scare the heck out of me.

 

Another muffler bearing thread? Oh, never mind.

 

You could:
Cut it like you suggested or try to get on it with a vice grip and turn it out.

 

Drill and retap

 

Remove? The? Exhaust? So? It's? Not? Near? The? Gas tank?

My brilliance is pure.

Or use a cutting method that doesn't involve sparks.

Or use a breaker bar/impact to break the welds on the nut.

 

Unless your gas tank is leaking, really the "sparks" from your grinder are cold by the time they fly two inches.....

But yeah, you could also do a make shift cardboard shield to prevent the sparks from ever getting to the tank.

Drill and retap is your best option if you are concerned. Oh also, if you have a full tank of gas, it has much less combustibility. It's the half tank that is most volatile.

 

FIRST thing to try before anything is to get some vice grips on the remains of the bolt and turn it through the weldnut. Spray with Kroil penetrant.