Muriatic acid to remove rust in gas tank

[Al L. in Wisc.]

I removed gas tank from Farmall 340 and have acid removing rust in tank; what can I use to plug the two top holes and when inverted, the bottom hole, to hold the acid in the tank? currently I have the tank in a small storage barn as it is raining and directions state don't add water to acid, also for ventilation.

I used a flashlight to peek at the progress last evening with tank on side and results are amazing. Any other tips and tricks for this process is appreciated.

 

[Steve@Advance]

You can use a pipe plug in the bottom. What's up top, a gauge hole and the
cap?

Maybe make a cover that will bolt on out of plastic or plywood and silicone
or a gasket. The cap will probably seal it fairly well.

But when you dump the acid, it will need to be neutralized. Rinse it with
water, then some diluted liquid caustic drain cleaner, then more water.

But once it's rinsed, it's going to flash rust immediately! Maybe some
fogging oil or some light oil poured in and tipped all around.

When it goes back on, I would fill it just a little at a time and check for
leaks, keep a close watch on it at first. There may be some pin holes if it
was seriously rusty.