Rust inside tank

[kruemel]

Hi Rolf!

Nein, ich habe keine Risse oder Löcher im Tank... Ich hatte damals geschrieben, das eine Beschichtung (kurzfristig) einen Riß dichten kann jedoch langfristig der Tank starken Mechanischen Vibrationen ausgesetzt ist und keine nachträglich aufgebrachte Beschichtung die gerade an den Knotenpunkten extremen Schwingen aushält. Wenn man die Schingungen unserer Einzylinder am Rahmen messen würde wäre das Arbeitsschutzrechtlich bestimmt eine Maschine, die man nicht mehr als 5 Miniten in der Stunde bedienen dürfte ;-)

gruss, krueme k(larheit)

[kruemel]

[Karl]

das " Mhmmm" war frech!

       

[Rütz]

I used battery (phosphoric) acid

No again! (though not very important)
Battery acid is sufuric acid, not phosphoric. It does not build up this black korrosion inhibiting phosphate coating ("Brünierung").

[rolf]

Anselm, ich danke dir für dein "though not very important"!

[Rütz]

  *knicks*

[Garnet Grylls]

@ Anslem
You are right, wrong acid. It cleaned to bare metal with no covering.
@ Rolf
You to are right... I coated my tank, I did not seal it.

Greetings
Garnet T(oo) much Acid

[korremann]

Karl:
Thanks for the explaining. Now I understand what Rolf meant about why sealer can´t close holes permanently. And yes an Einzylinder vibrates a lot.

I don´t know if there is any holes in my tank, so maybe I don´t have a problem in the end.

But I will try to remove the rust with acid and screws: Afterwards I must see how the condition of the tank walls are, to find out what to do.

Thanks to all of you, it was something of a subject!

Bjarke

[Taz]

Hello Bjarke.

To add to the confusion( )...I had a small discussion with Rolf in another thread and we discussed another approach to the tank handling.
If you find your tank still hole-free then you can either coat it (with a free choice of products, "Kreem weiß" seems to be more on the flexible side, "Kreem rot" like POR15 is reported to create a more "stiff" coating) or you can do what Rolf did to one of his tanks: leave it derusted without coating and just add a sip of oil to the gas every now and then. Two-stroke machines that have no separate oil tank and thus keep the oil-gas mixture in the main tank seem to have their tanks in much better condition rust-wise... so this idea sounds quite sensible.

As my own bike's tank (R25/3) will cause a tremendous amount of work to have it coated properly (with all the tubes and stuff going through or protruding into it) I am considering to follow this method. My bike will have to stay in the "cold" during winter time so I will empty the tank every autumn to avoid long inactive periods with watery fuel....

Best regards, Tassilo

[korremann]

Hi

Yes the subject did became a little confusing I have also a 25/3 and you are right, it could maybe be hard to get such a tank proberly coated.
The tank I have the rust in, is a DKW and that is a two-stroke so there will be oil in the gas. But the tank have been lying in a garage since 1965.

My mom says that phosfor acid would be the best chemical product to remove the rust with in the tank. Phosfor acid won´t damage the metal. The solution of acid should be about 1-3 %. So instead of bying some expensive product I will just get som phosfor acid and mix the solution my self.

And to Karl:
Phosfor acid in a weak solution will not damage the tank walls. Salpetersäure (HNO3) is a much more strong acid and it  would on the opposite hand eat the tank walls (Salpetersäure "eats" iron, but not steel) So HNO3 is good agains unwanted material on steel.

Thanks to all of you, it was very helpfull with all the many answers!

Bjarke

[Taz]

Hi Bjarke.

...My mom says that phosfor acid would be the best chemical product to remove the rust with in the tank. Phosfor acid won´t damage the metal. The solution of acid should be about 1-3 %. So instead of bying some expensive product I will just get som phosfor acid and mix the solution my self...

Try using Coke after applying the screws (less than 1%, but reported to be working in several other forums as well)...easiest to obtain in my eyes...

And if it didn't work with the first bottle you have a brilliant excuse to empty the rest into your body 

Best regards, Tassilo

[korremann]

Hi

Yes that would be a good idea, but it´s pretty easy to get phosfor acid. Yesterday I bought a product wich contains 5 % phosfor acid, and it only cost about 1,5 euro

Bjarke

[rolf]

Skâl!

[Dave]

G'day, happy new year!

With regard to Phosphoric Acid, its used in aviation for aluminium preparation, sold here by Turco as "WO1". Some caution has to be used when using it as a de-rusting chemical:

1. It takes a couple of hours to start working, afterwhich (I think Karl mentioned) heavy rusted parts will have all rust removed, potentially leaving holes.

2. It can be quite hard to rinse off and if rinsed directly in water the surface sometimes oxidises instantly. I use white spirits.

3. The surface can turn a quite dark colour (Rolf - can you elaborate, is this actually a phosphate coating?).

See the examples below - recently I needed to de-rust these springs (old Harley, left - before, right - after). About 6 hours in the acid and they were great. In this case the dark finish was a bonus as they are supposed to have a manganese phosphate finish and I didn't want to put the springs through that process.

Dave.

[mekgyver]

Hi Dave,
thank you for the information about that Turco WO1 

But i think, there will be no chance to buy this acid in Germany.
I found this statement in a nederlands Porsche 356 Forum :

PostPosted: Fri Jan 05, 2007 7:22 pm   
Kun je trouwens bestellen bij Turco, groothandel in chemicaliën, zitten in de buurt van Leusden, Kleinste verpakking 20L.
_________________
Groeten, Knick

What about Fertan ? I think, it will do the job as well as your choice.

Regards, mek

[rolf]

hallo Dave,
it is near by "phosphating". As I know for "real" phosphate coating there must be used a little (!) more than only phosphoric-acid... but i am not a chemican...so i 'm not sure, but it was now (a little bit) "rust-save".

Rolf

[Karl]

Info:

- The POR15 "Tank Sealer Kit" contains such a liquid / rust transformer, which creates such a black surface.
I tested it last year and was wondering about the black surface, after I de-rusted the "number plate" of my bike.

Greetings,
Karl

[Dave]

Just adding some pictures for reference:

I recently set to work on my tank with phosphoric acid (WO1, see my previous post). The right knee pad flange had a lot of corrosion, this photo shows the conversion process almost complete, some of the rust is still present.

Unfortunately I'll have to cut the side out of the tank as this is too badly gone, at least it makes it easier to spot weld a new flange on

What I like about the acid method is at least you know exactly the state of your tank, ie no rust but lots of repair work to do!




Another example of an acid cleaned part - rear mudguard before and after.