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Hydrochloric acid to disintegrate rust to remove pin in bearing

Hydrochloric acid to disintegrate rust to remove pin in bearing

Hydrochloric acid to disintegrate rust to remove pin in bearing

(OP)
Hello

I have a series of pins which have seized in a bearing.

Has anyone had experience with using Hydrochloric acid to break the corrosion between a pin and the inside of the inner race of a bearing? This has been suggested to me but i have had no experience with this practice.

We need to remove the pin to replace the bearing, but due to the location of the pin and bearing we are having trouble extracting the pin....

Thanks
Ryan

RE: Hydrochloric acid to disintegrate rust to remove pin in bearing

Some say that Coca-Cola also works. It will not disintegrate your machinery like the HCl will  

CRC 5-56 usually works well if we shall be more serious.

RE: Hydrochloric acid to disintegrate rust to remove pin in bearing

(OP)
Thanks Skogsgurra

But we are passed the stage of simply using a liquid penetrant. We have put 40 tonnes onto this pin and it only moved slightly then bound up.

I am looking for someone who has used HCl to disintegrate rust between two mated surfaces.

ie.
hydrochloric acid + rust --> ferritic chloride + water
6HCl + Fe2O3 -->  2FeCl3 + 3H2O

Has anyone used this theory in a practical manner?

Thanks
Ryan

RE: Hydrochloric acid to disintegrate rust to remove pin in bearing

What are the material that the bearing and the pin are made off?
Are you sure it is corrosion? If the pin and bearing are from stainless steels then it might be a cold welding between the pin and the bearing inner race.

RE: Hydrochloric acid to disintegrate rust to remove pin in bearing

(OP)
Thanks Israelkk

Yeah, i had considered cold welding as a possibility, early on but because the pin actually moved i ruled that out?

Unfortunately we have not been able to remove a pin or bearing as yet, so we cannot confirm what the exact cause of the problem is. Also the machinery is still in service so we have limited time when we can attack each unit.

The machinery is situated on a wharf, so is exposed to salt water spray conditions.

The materials are: Pin - stainless steel 316, bearing - some type of carbon chromium steel.

We are looking at putting in a plain spherical stainless steel bearing, after we have removed the current ones. Both the current and the intended replacement bearings are supposedly maintenance free bearings, which have a fabric liner which the inner ring runs on. These bearings have no lubrication and have seals on the inner ring to keep out contaminants only.

I am sure that it is corrosion because several of the pins have rust coloured dust on them, from rust stained water running down them - which seems to be coming from the inside of the bearing!

Does the Aerospace field use only Ceramic bearings for avoiding colding welding?

Thanks
Ryan

RE: Hydrochloric acid to disintegrate rust to remove pin in bearing

(OP)
I know that the pickling paste that i had used during my apprenticeship was based on HCl. We used it for mainly for cleaning welds after tig welding, but had occassionaly used it to clean rust off steel items.

Thanks
Ryan

RE: Hydrochloric acid to disintegrate rust to remove pin in bearing

I have never used ceramic bearing we use stainless all the time but not in the same environment as yours. Is the pin is press fitted to the inner race? if so it may the cause for cold welding. The fact that the pin moved a little "and then stopped" can be an idication for cold welding. If it was just rust it should not have been stopped. The nature of cold welding is that it builds up. It starts moving and then more and more area become welded until the area large enough to resist the puling force.

RE: Hydrochloric acid to disintegrate rust to remove pin in bearing

(OP)
Thanks Isrealkk

Sounds interesting! The pin is not press fit into the inner ring of the bearing.
What special precautions do the aerospace industry use to avoid cold welding? What type of bearings do you use?

But as i said, i don't think it is cold welding because it moved a little when we put a high load onto it (I think that this is the rust on the inside of the inner ring binding up the pin). And because there was rust dust on the stainless pin which came from somewhere inside the bearing!

Thanks
Ryan

RE: Hydrochloric acid to disintegrate rust to remove pin in bearing

Are you certain that it is not
a tapered pin rather than a spring
pin?  Sometimes spring pin holes
are not drilled all the way thru
and may have to be extracted from
the far side. If the pin moved
initially, you have broken any
microwelding or rusting, so the pin
should move easily. I have seen
easy outs used to remove some pins.

RE: Hydrochloric acid to disintegrate rust to remove pin in bearing

Is it possible to heat the material? Rust is Fe2O3.+XH2O The bound up H2O takes up space. Heat drives off the bound up H2O and this may assist with the movement.

RE: Hydrochloric acid to disintegrate rust to remove pin in bearing

(1)"We have put 40 tonnes onto this pin and it only moved slightly then bound up."

(2)"The fact that the pin moved a little "and then stopped" can be an indication for cold welding."

I don't have a good mental picture of the pin and bearing arrangement, but I would base the next repair attempts on statement (2).  I'd say either the pin galled/cold-welded and is now seized hard, or it hit the a shoulder or the bottom of the hole.

I might be thinking about using a carefully guided carbide drill first, to put a hole thru the pin to allow using oil or grease to hydraulically remove the pin in reverse. Then, if necessary, enlarging the hole to reduce the pin to a thin shell that can be collpased inward, broken and picked out.

RE: Hydrochloric acid to disintegrate rust to remove pin in bearing

(OP)
Thanks
DiamondJim - The pin i am talking about is a stainless pin which passes through a spherical bearing, it is not tapered nor a spring pin.

rnd2 - I had a maintenance crew apply heat to try to break the corrosion, but it did not seem to help. They seemed to have gone overboard with the heat and now the stainless steel is very hard.

Tmoose- I would not attempt to drill through the pin now due to the heat that has been applied- ie hard stainless. I will have to wait till i finally get the bloody thing removed before i can find out whether it is corrosion or cold welding. Although all indications are that it is corrsion rather than cold welding due to the fact that there is rust staining on the stainless pin...

That brings me back to my original question, incase it has been forgotten---Has anyone had experience using Hydrochloric Acid to disolve rust?

Thanks
Ryan
www.mooring.co.nz

RE: Hydrochloric acid to disintegrate rust to remove pin in bearing

Another possiblility is that these
are dowel holes used to keep two
separate rings aligned.  Which
means that they could be seated
in one ring i.e. blind holes and
the mating part have thru holes
with a slightly larger hole.
Is it a double spherical bearing?
Do you have the serial number and
manufacturer model number.
They might use these for machining
purposed to keep the parts alinged
to grind or clean up the od or id.
as a unit.  Are they angularly
arranged using equal spacing?

RE: Hydrochloric acid to disintegrate rust to remove pin in bearing

(OP)
sorry Jim

You are barking up the wrong tree.

There is no split pin, roll pin, spring pin nor dowell pin, the pin inserted into the bearing is a plain machined stainless pin.

Apparantly posting email addesses on this website is not allowed, so if you look at our website and find my address, i will return email you the drawing.

Regards
Ryan
www.mooring.co.nz

RE: Hydrochloric acid to disintegrate rust to remove pin in bearing

I have used mureatic acid for a similar purpose and it works great. It is sold in a hardware store to adjust the PH of pools, and has a concentration of 20 - 45%. You have to dilute it a lot from that. Do not let the acid spill on concrete, because it will eat it, or leave container without lid on it. After you get it apart you should wash everything in baking soda and water, then oil it with WD 40 or something similar.
Sometime you need more than a 40 ton press to free corroded parts.
Cheers!

RE: Hydrochloric acid to disintegrate rust to remove pin in bearing

(OP)
thanks Aviat

will give it a try!!

Cheers
Ryan

RE: Hydrochloric acid to disintegrate rust to remove pin in bearing

Mureatic acid is I think hydrochloric, so you may have your answer.
Good Luck.

RE: Hydrochloric acid to disintegrate rust to remove pin in bearing

(OP)
Hello Aviat

How long did you leave the HCl on for approximately?

Thanks
Ryan

RE: Hydrochloric acid to disintegrate rust to remove pin in bearing

Ryan,
Tried the URL that you listed and
keep getting a blank page.
Would like to see the drawing.

RE: Hydrochloric acid to disintegrate rust to remove pin in bearing

(OP)
Gidday DiamondJim

There has been some maintenance done on the website as of late, but i just tried it and it worked for me. It does however route thru to another webpage, so maybe try these if it still doesn't work.

www.moormaster.com
www.fastmoor.com

ok
cheers

Ryan

RE: Hydrochloric acid to disintegrate rust to remove pin in bearing

Ryan,
Both url take me to a blank page.
Strange, I will try later.
Thanks.
I worked for Rotek Inc. and also
Timken and am curious what this
bearing looks like.
Sorry to be of so little help.

RE: Hydrochloric acid to disintegrate rust to remove pin in bearing

(OP)
The newly routed webpage directs to a macromedia flash webpage, this may be the problem? This is a bit of a problem if persons cannot connect if they don't have flash. Hmmm

anyway if you are still interested, you could post your website address, and i could send the drawing?

Cheers
Ryan

RE: Hydrochloric acid to disintegrate rust to remove pin in bearing

Ryan. Cool website But what's this Gidday?? G'Day Mate.

RE: Hydrochloric acid to disintegrate rust to remove pin in bearing

(OP)
Good day!! rnd2

RE: Hydrochloric acid to disintegrate rust to remove pin in bearing

Now I'm giddy!  ;)

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