how far can oil impregnate steel?

[meadow street]

g'day ,

I have some old 16mm plate which has some oil spots/patches on the surface.

how far do you reckon oil gets down?

can an it simply be degreased, grinded and welded without affecting the weldment ?

how do oil deposits affect welding generally ?

regards

meadow

[Master Splinter]

Wipe with lacquer thinner and you're good to go. You're more likely to pick up crud in the weld from poor storage of the electrode than from surface contamination by oil.

Super Cheap makes a spray can of pre-paint cleaning solvent which is handy for infrequent use.

It can be a different story with cast metals, where oil can penetrate over many years of service.

[Grahame Collins]

Hi,
Just a bit of a safety nanny thing before you weld!

As with anything on a metallic surface just be a bit careful about breathing what comes off it as a fume.

Some of the older cleaners had some really nasty by by products in the fume generated.

Take an ordinary electric fan and place it behind you when you weld. Any fume and smoke will be blown out of your breathing zone. A light scuff with a disc to remove rust and crud is never a bad idea as well.

The oil (a hydrocarbon ) if not removed could well form hydrogen gas bubbles at the root of the weld .Under conditions of stress and loading, the bubbles expand over time to eventually form cracking at the root of the weld bead.

If the weld was part of a critically loaded structure they could be problems.
However if it is only lightly loaded structure, I would not for see any problem.

Cheers

Grahame

[sossity]

Hi,
Just a bit of a safety nanny thing before you weld!

As with anything on a metallic surface just be a bit careful about breathing what comes off it as a fume.

Some of the older cleaners had some really nasty by by products in the fume generated.

Take an ordinary electric fan and place it behind you when you weld. Any fume and smoke will be blown out of your breathing zone. A light scuff with a disc to remove rust and crud is never a bad idea as well.

The oil (a hydrocarbon ) if not removed could well form hydrogen gas bubbles at the root of the weld .Under conditions of stress and loading, the bubbles expand over time to eventually form cracking at the root of the weld bead.

If the weld was part of a critically loaded structure they could be problems.
However if it is only lightly loaded structure, I would not for see any problem.

Cheers

Grahame

worth checking out this link
http://www.brewracingframes.com/id75.htm
Argon, trichloroethelene and heat can make phosgene gas. I used to use loads of tric in the 80s to clean everything. Lucky I didn't do any. Tig. Carb cleaner can cause this so watch out.

[Grahame Collins]

trichloroethelenes where supposed to be banned in the early nineties.

C&P from an old WIA manual circa 1995
<WELDARC
A40
MANUAL
Page
l l


Vapours from chlorinated solvents can be decomposed by the heat of the arc (or flame)to form PHOSGENE, a highly toxic gas, and lung and eye irritating products.
The ultra-violet (radiant) energy of the arc can also decompose trichloroethylene and perchtorethylene vapours to form phosgene.

Do not weld or cut where solvent vapours can be drawn into the welding
Or cutting atmosphere or where the radiant energy can penetrate to atmospheres containing even minute amounts of trichloroethylene or percholorethylene.>

Percholorethylenecwas was found in dry cleaning solution.I can't comment on the argon connection but even in the old Welding Institute of Australia mags in was hammered in to us about the welding radiation acting to form phosgene.

I can envisage someone wishing to clean for welding pulling an old can of carb cleaner out of a cupboard and letting rip with disastrous results .

I had a booklet from the union many years back and it listed all of (what they knew then) the metals that could cause harm through contact ,inhalation etc,

The list was extensive and it makes you wonder are there some consequences down the track for those metalworkers who worked with the materials.

Grahame

[Karl Robbers]

trichloroethelenes where suppose to be banned in the early nineties.

I can envisage someone wishing to clean for welding pulling an old can of carb cleaner out of a cupboard and letting rip.

I had a booklet from the union many years back and it listed all of (what they knew then) the metals that could cause harm through contact ,inhalation etc,

The list was extensive and it makes you wonder are there some problems down the track for those metalworkers who worked with the metals.

Grahame

Really lends weight to the old statement "no such thing as an old boilermaker."
We had to be careful working on bucket repairs at the mine where I worked. The ore contained Zinc, Lead, Copper, Silver and Gold plus traces of iron. Good ventilation, hygiene and a force fed head shield were the order of the day, you have never seen or smelt smoke like it.
Another couple of jobs spring to mind as examples of the ability of substances to penetrate the surface of metal come to mind. One was repairing walkways in a sewerage treatment plant. You could not wash, burn or grind the smell out, as soon as heat was applied the goodness filled the air before your very nose. My absolute favourite was repairing a cast iron impellor from a pump that handled offal from a meatworks. It had been washed, sandblasted and actually looked and smelled quite clean - until you got some heat into it. While welding on it produced a beautiful green flame and fat oozed out of the pores along with an evil stench. I found that the secret was to keep my shield down and keep going while the rest of the workshop was expressing their disapproval with rags over their noses
Metal is actually a lot more porous than many realise.
For what you are doing Meadow, as long as you are aware of solvent reactions, you will be fine.

[meadow street]

thanks for the inputs.

always rely on good comments here!

regards

[sossity]

I can envisage someone wishing to clean for welding pulling an old can of carb cleaner out of a cupboard and letting rip with disastrous results .

Grahame

Yes, it was almost me! I still have a couple of cans of Colclene which is pure trichloroethylene. I was very likley to use it for particularly important welds and consider myself lucky to have seen the warning.
Regarding the Argon, it is completely inert, but i suspect it is required to stop the chemicals reacting with the atmosphere and form something else, because I did read elsewhere that Argon was needed to create the phosgene.
I use a lot of steel from a scrap yard, and I agree about how steel can store bad smells, even when it looks completely clean and has been sanded shiny. I got some last year that I'm certain was from a sewerage plant but you couldn't tell by looking at it. Only after welding did the smell appear.
Also, I think Cast iron is very porous, isn't it? A while back, I took a 60 year old cast iron cylinder head to a specialist, because the exhaust port had worn oval (the exhaust was just a slip fit, so not a good seal anymore). The guy said he wouldn't try to weld it because sulphur gets absorbed into the iron after all those years and makes it just spit off any attempt at welding.

[Grahame Collins]

I chased up the argon reference.
It is a not only but also, type of thing. Sossity is correct.The inert atmosphere provides a medium for other reactions read more here:

http://www.centralstreetscene.org/fo...ad.php?t=35574

The information provided by a chemical engineer also mentions electrical contact point cleaner.He points out those solvents which are labelled inflammable or highly inflammable are safe to use ( normal precautions with arc flame and sparks apply).

Basically the reaction can occur through welding heat processes but argon and some other shielding gases can cause a more intense reaction-at least that's what I got from the reading .

Solvents that are non flammable are the ( phosgene) danger.Its a fairly big read but well worth it.

Some of the solvents that I use are going to be labeled and quarantined well away from welding and cutting operations. Not that I keep them nearby anyway but I may have senior moment one day or not be around at the time to warn some one who may be using my welding equipment.

With the cast iron , I prefer the oxy acetylene welding method. This is because you can get a a pool of molten cast iron and push it around with the flame and flux it and mostly the crap flows out with the flux which is removed as a scale from the top on cooling of the metal.

The problem is, I do not see cast iron cast iron welding flux available any more. I have one bottle and when that gone ??

Grahame

[Karl Robbers]

Good news Grahame. http://www.superiorflux.com/cast_iron_welding_flux.html
They will ship internationally too.