Nitric acid to remove broken exhaust studs.

[Geronimo '74]

--------------------------------------------------------------------------------

In another thread I saw a pic of a set of bottles (3). It was a "tap out kit"
One bottle contained a liquid with nitric acid.
the idea is to make some sort of dam (with clay?) around a snapped of stud and fill it with the acid.
It is supposed to disolve the metal stud and leave the aluminum of the head intact.
The other bottles contain a neutralizing liquid.

I bought a bottle of nitric acid today, tech grade, 61.4% (40°).
Maybe it's worth trying to remove a stud this way before I have to drill it out and risk damaging the head.


Does anyone of you know:
Is this concentrated enough to disolve a metal stud? (I'm guessing it is)
How long would you estimate it would take to disolve the stud enough to remove it??

Weird question I know...

(I've posted this in OT as well, by mistake...)
__________________

[GaryR]

Not a chemist but -

Passivation

Although chromium (Cr), iron (Fe) and aluminium (Al) readily dissolve in dilute nitric acid, the concentrated acid forms a metal oxide layer that protects the metal from further oxidation, which is called passivation. Typical passivation concentrations range from 18% to 22% by weight.

Have it drilled out by a shop if you cant do it..

[theiceman]

i would think it would atack the softer allumunum before the harder stud ... but I am not chemist.
i would get the proper stud removal kit.

[James Brown]

I have seen this work and it works good, attacks the steel but not the aluminum

[Kemo]

I used to be a chemist, but I dont remember trying to react aluminium and nitric... I did fart around with some sodium metal once It seems like aluminum does not react in solution with nitric acid, basically what Gary said.

4.4.24.2 Reaction of Metals with Nitric Acid

personally, id be interested to see how it all pans out.

[tadd]

Well I am a chemist and nitric will do a fine job chewing up aluminum. Especially for fine structures like thread forms.

[James Brown]

The Tap-out kit does work maybe the chemical name is wrong but the product eats carbon steel but does not harm aluminum. It works great if you snap off a easy out in the stud. form a damn around the stud and put a few drops on the stud and watch the metal dissolve away not harming the aluminum. flush with water and clean out the threads. great product.

[c0metdot]

Who hasn't had an easy out break off and leave it's impenetrable tip embedded in a stud. Eeeesh, lots of swearing.

Would be interesting to learn about an acid solution, solution.

Google doesn't know. Maybe I didn't ask the right question. Is there a link?

[MattKellett]

I have used Tap Out many times to remove broken taps in aluminum.

It won't attack the aluminum only the stud in your application. I use a sculpting clay to form a dam around the broken tap.

You want to try and replace the fluid while removing the stud, as after a while the acid seems to lose some ability to attack the tap. So i normally suck it out with a syringe and replace every hour or so.

[aj88cab]

Just to thow in some info...not specifically about desolving steel studs...but along the same line as the use of acids with aluminum.

I have been researching what it would it would take to economically (as in cheaply) remove the peeling chrome from the original set of chromed Fuchs that were on my car when I got it. Chrome shops I have checked with want upwards of $100 or $150 per wheel...oh, and I won't be using these wheels for DE's in case you are worried

Now I am certainly no chemist, but what I found was that otherwise caustic acids like muratic acid can be used with care on aluminum. The www.forum.CaswellPlating.com web-site forum has some particularly informative threads regarding the removal of chrome and the underlying nickel from aluminum as well as DIY plating in general. The The Finishing Industry -- Anodizing, Plating, Powder Coating site is another informative site (albeit a bit confusing to navigate).

I have not tried the chrome on aluminum stripping process described on the Caswell site yet, but plan to give it a try when the current crop of projects are done (whenever that will happen). I understand that Fuchs are an alloy and not pure aluminum, so if I end up ruining a wheel I will let the forum know (they are pretty ugly now anyway).

The following is a thread that I found that I thought particularly applicable to the use of acids on aluminum (in this case for chrome & nickel stripping). Just a beginning but a good starting point...and I take no responsibility for any experiments you try

I need to strip chrome from aluminum?

Getting back to the OPs question, the bottom line seems to be (as others have stated above) that aluminum seems to have particular properties that allow it to withstand these acids when applied in the proper concentrations.

[Geronimo '74]

need to get me some clay to make a dam.
Now I only have a few drops of acid on the stud remainders.... not nearly enough to disolve the entire stud.

Should there be gasbubbles forming in the acid?? Or is it a slow proces the has no visual indicators that it actually is disolving?

(anybody know where I can buy the origanal tap out kit??)

[egertk]

I just got some of this stuff from Western Tool & Supply Co., not sure where to get it in Europe though.

[gregwils]

Use a center punch to start a pilot hole, then get a reverse drill bit. The bit can be smaller than the stud. If you really want to be certain it will come out, heat the head first. Must easier, simpler and safer than the acid, but not a guarantee. If the reverse drill doesn't work, then try the acid.

[AlfonsoR]

When you guys say it doesn't attack aluminum, are you saying this from visual inspection with your eyes, or has someone actually inspected with a mciroscope and maybe done some integrity testing? Just because it looks good, doesn't mean it is.

[jpnovak]

HMM I wonder what the metal content of Dilivar is... Would this still work?

I am thinking head studs broken flush to the case. Better alternative to EDM.

[AlfonsoR]

Originally Posted by tadd

Well I am a chemist and nitric will do a fine job chewing up aluminum. Especially for fine structures like thread forms.

^^^^^We got one expert that says no to do this. Make sure you do your homework well before you try, just my opinion.

[Packy]

where do you get "Tap-Out"? I searched google and got roid juice. I have a broken stud in an aluminum intake manifold on my F150. I am willing to try this stuff out and post pictures and the process.

My other means of removing the stud are very expensive or can be a PITA so if this works I will be one happy puppy.

[Packy]

Originally Posted by egertk

I just got some of this stuff from Western Tool & Supply Co., not sure where to get it in Europe though.

never mind

my bad.

[Packy]

Western Tool and Supply said they were on back order with the stuff for about 50 cans...

They also said is was made by "International Tool Supply". All I could find of them was an address:

13340 S. 1300 W.
Riverton, Utah 84065

Edit:
and phone number:
801-446-6838
nobody is answering and mailbox is full. This is starting to sound like a victim of the economy.

Metal Forming Magazine claims "the product works well on materials such as stainless-steel, nickel, titanium and alluminum alloys." Apparently it reacts with the carbon in the tool steel.

DON"T USE ON HIGH CARBON MATERIALS!!!