Thanks a lot for your immediate respose.

Yes we considered the use of terne coated steels initially but due to
environmental standards in place had to drop them. With regards to HDPE
tanks esp via rotomolding .. The process by itself dosent allow
reasonable costs associated with them esp in high production volume. So
is the reason behind coatings that would inhibit this corrosion
process.

Also we are seeing this active corrosion in rectangular fuel tanks
while our cylindrical counterparts dosent seem to experience any
service failure. Is it because of the reduced contact area of the
water. ??

Thanks again !!
wrote:
> "Barath" > wrote in message
> > 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
>
> Moisture in the diesel fuel is the most probably cause, and it can be there
> due
> to contaminated diesel or by condensation. It is not too likely that it
> enters via
> porous weld zones (although lousy welds will be attacked far more rapidly
> than
> proper ones.)
>
> If there is no moisture or other electrolyte in systems like this, corrosion
> does not
> occur. Sulfur content alone does not mandate corrosiveness, if there is no
> effective
> electrolyte to allow the electrochemical reaction to proceed.
>
> Epoxy coating is one way to make the metal tanks resist corrosion, but the
> polymer
> has to be (1) one well suited for the application, (2) applied to a well
> prepared metal
> surface, (3) allowed to cure properly.
>
> In production, you might find that it could be more cost effective to look
> at different
> materials of construction. Terneplate is a base metal (steel) which has
> been dipped
> in and coated by an alloy of ca 85% lead and 15% tin. It has been used for
> years in
> fuel tank construction.
>
> Our company used to own a corporation which produced fuel tanks from high
> density
> polyethylene. I believe VW used them, and they were tough and non
> corrosive.