Fuel tank corrosion

A product called ChemPrime, made by Al Con Chemical in Louisiana, is phosphoric acid plus a zinc based chemical that prevents future rust.

Works like phosphoric acid. Put a gallon in a tank, leave 6 to 8 hours, then roll tank to soak all surfaces 6 to 8 hours. Drain, but do not rinse, allow to air dry. This creates the zinc conversion that prevents future rust.

Worked for me.

Slick

We P&O'd most process piping and such with citric acid. It takes a while and leaves a fairly nice chalky coating inside. Also hooked up LP stm. line to keep reservoir heated as solution was circulated. Generally took us 18-24hrs., depending on client requirements, to complete a pickle.
Having multiple pets & the wife farting around in the vicinity I chose a method having little to no hazards. I am a firm believer in Murphy's Law, Especially At home with family present.
Also used some 93% HCL to zinc plate something the quick way once. Very bad. Worked well. Very hot, noxious, dangerous. Never again. The piece has sat outside for 15yrs. and no corrosion. All on a dollar wager. I now question myself prior to taking action. Leaves should remain on the trees & birds not fall from the sky.