The changing temperatures, from hot to cold of the exhaust system together with changing moisture conditions can speed up the rusting of the flange bolts. If the rust progresses, it could reach to the threads and these could go useless. It is essential to release and replace the flange bolts. You would need to apply heat to remove the rust from the threads. If the threads are unusable, you have to cut the bolts from the flange.
1. Check if the area on the flange bolts has no fuel lines as well as combustibles. Clear all combustibles underneath the vicinity for safety.
2. Protect your hands and eyes using goggles and gloves.
3. Have a fire extinguisher close to you in case on any case that a fire could start.
4. Ignite your torch carefully. Make sure that the bright blue flame is one half or an inch long.
5. The tip of the torch should be 6-8 inches away from the flange bolt until it has a dull orange color. Turn off your torch. Heat the bolt slowly so do not use an air trigger.
6. Let the flange bolt to cool down and then place the socket that fits the bolt to the ratchet.
7. You have to slide the socket to the nut that is situated at the flange bolt. If the bolt loosens, continue doing the same process to the rest of the bolts. If it would not budge go to the next step.
8. Set your flames again but now, set the tip further at 3-4 inches.
9. Heat the bolt once again and when you see that it has a bright orange glow, use the air trigger to blow more oxygen. The bolt would then start to melt.
10. Turn of your torch and then quickly hammer the threaded side of the flange bolt. Repeat the process until the bolt is out of the exhaust.
11. Let the hot bolts cool for 30 minutes before leaving the area so that no combustible materials are left lying on the ground.
12. Throw the cut bolts after another hour or two to ensure that the bolts are totally cool and will not cause fires on the garbage bin.