Looking for opinions here. If someone is a professional welder, it would be helpful. I have my 67 F100 4x4. There is a place in the frame that is rusted through on the left rail right under where the cab and bed come together. I am planning on welding a 1/4" plate to it plus 3/16' strips to the top and bottom to make a wrap around reinforcement. My question is; Should I remove the gas tank prior to welding? I plan on putting the welder ground clamp as close to the area I am welding, disconnecting the battery and disconnecting the orange sender wire. I may also drive a ground rod into the ground just outside my garage door and connect the truck frame to it via a battery booster cable. My thought is that with the loop being disconnected by disconnecting the battery cable, disconnecting the orange sender feed wire grounding the truck to earth ground and placing the welder ground very close to my welding area, the current, wanting to take the shortest path of least resistance, taking out the gas tank should not be necessary. After all, muffler shops weld on cars all the time with doing nearly what my safety plan is. I have had several opinions about this. None agree with each other.

 

Yes that will work. Necessary? I don't think so. As long as the gas cap is on and there is no open fuel lines you'll be fine. Be sure to support the Frame on both sides of weld before welding. The heat could cause frame to do some funky things. Your best bet would be to find another frame but I know how life is and sometimes that's not an option.

 

On the 1/4 plate .Don't leave the ends square. Either cut out a semi circle on each end or make the end a point. My Late Dad who was certified Union Pile Driver welder for over 30 years gave me the very best welding advice ever. Always make your weld the best that you can because your life or someone else's might depend on your weld holding. R.I.P. Dad.

 

Rounding the corners is very good advice, supporting the frame is also good. Take your time cleaning up the frame, remove all scale and rust. You may want to cut out the bad area and weld in new material. If you lay a plate over the area you are only going to cause a great place for rust to start.

 

For me and the gas tank it is not that the arc will go to the tank but the fumes and the spark of the arc where you are welding that you need to worry about in my book.
You may not smell fumes but sparks can and will find them.
I say pull it and place it outside the garage far away.
Dave ----