Diesel Fuel Tank Corrosion Issue

Dear All,

I have following this grp a lot quite lately and found it
justifying to post my query here.. I am associated with a leading OEM
manufacturer of commercial vehicles in India. We are grappling with a
rather familiar problem right now - FUEL TANK CORROSION..

To have a forward on this problem. Mild steel uncoated tanks corroding
at the weld lines thereby causing leakage issues especially at the
bottom. Also the tank construction incorporates baffles which makes
reaching inside quite tough.

It is my thinking that the fuel tank corrosion happens especially when
the humidity inside the closed tank is high which causes water-vapor to
condense and react with steel, thus giving rise to excessive rusting.
The water vapor usually seeps into the fuel tanks along improper weld
lines, which serve the purpose of defective zones. Also the presence of
sulpher in diesel, especially in the presence of water at the bottom of
the tank, aggravates this situation causing the weld lines to
preferentially corrode in the absence of oxygen thereby causing the
leakage that we are experiencing. Also the rust particles as a result
clog the diesel fuel filter and the pump thereof.

POSSIBLE REMEDY :

I was thinking of flushing the tank with phosphoric acid as a
pre-treatment measure to Ferric Phosphates and then give a epoxy based
primer coat in the inside as well as outside.

Please adivice me on the same ...

Regards,
Barath