[melsdad]

I have some steel angle I am making a cart frame out of for my Thunderbolt. It has some light rust on it so I was going to sandblast the steel to clean it up. My question is will a wipe down with acetone before TIG welding be enough or should I still hit the surface with a sanding disc to shine it back up before welding?

Thanks

[MosquitoMoto]

Definitely sand/grind that rust off.

I undertook two jobs in the recent past (both just mild steel), one where I had no opportunity to clean the steel other than with an acetone wipe, the other where I ground off the scale, prepped properly and then welded.

The results were very different. The 'dirty' steel, which honestly wasn't very dirt at all, gave sparklers during welding, brought impurities to the top of the puddle and returned a crusty weld bead. The clean stuff welded like butter and the end result was a shiny, even bead.

The dirty stuff will weld, just nowhere near as well. Tig loves clean.



Kym

[Poland308]

If it was sand blasted then it should be clean metal. At that point I might wipe down with acetone or alcohol to get rid of the sand blasting dust but I wouldn't worry about getting it shiny.

[LtBadd]

Definitely sand/grind that rust off.

I undertook two jobs in the recent past (both just mild steel), one where I had no opportunity to clean the steel other than with an acetone wipe, the other where I ground off the scale, prepped properly and then welded.

The results were very different. The 'dirty' steel, which honestly wasn't very dirt at all, gave sparklers during welding, brought impurities to the top of the puddle and returned a crusty weld bead. The clean stuff welded like butter and the end result was a shiny, even bead.

The dirty stuff will weld, just nowhere near as well. Tig loves clean.

Kym

If I understand the question, he is asking about wiping it down AFTER sand blast. If you have a good blaster that should be fine, however you can try a wipe and look at the rag/paper towel, if it looks clean then no need to continue.

Not seeing the condition of the angle, it could be if the rust is too heavy then a quick hit with a flap disc after blasting would be preferable, if you're unsure try a drop piece.

[Braehill]

Brian,
Sandblasted metal needs no further prep unless you plan on putting a bevel on it. If it's sandblasted well enough to take rust and mill scale off, then there almost assuredly can't be anything left on the surface. Now unless this angle has lived it's life in an oil bucket I won't even consider wiping it with anything. I'm not sure when this kick of wiping everything under the sun with acetone started but, I've never wiped a single thing I've Tig welded since 1978 with it and I've made out just fine. Fact is, only time I break out the acetone is if I'm going to superglue something.

I worked around a small refinery while half of it was being built and didn't see a single can of acetone. I work in a Hydrogen plant that has all manor of high pressure piping made from Carbon, stainless, duplex, Hastalloy, Duralloy, Alluminum, Inconel, you name it, in service from -434*F to 2100*F and there isn't a single can on site. I just moved back to my former plant making cryogenic liquid and sure enough, same thing, none to be found. Miles and miles of welds and no acetone to be found.

If there is any glue residue or something of a hydrocarbon base on your metal, then by all means wipe it with acetone, but other than that, can anybody tell me what this practice accomplishes. Maybe I'm missing something about acetone that others have picked up on.

Sorry, rant's over, carry on.

Len

[LtBadd]

Brian,
Sandblasted metal needs no further prep unless you plan on putting a bevel on it. If it's sandblasted well enough to take rust and mill scale off, then there almost assuredly can't be anything left on the surface. Now unless this angle has lived it's life in an oil bucket I won't even consider wiping it with anything. I'm not sure when this kick of wiping everything under the sun with acetone started but, I've never wiped a single thing I've Tig welded since 1978 with it and I've made out just fine. Fact is, only time I break out the acetone is if I'm going to superglue something.

I worked around a small refinery while half of it was being built and didn't see a single can of acetone. I work in a Hydrogen plant that has all manor of high pressure piping made from Carbon, stainless, duplex, Hastalloy, Duralloy, Alluminum, Inconel, you name it, in service from -434*F to 2100*F and there isn't a single can on site. I just moved back to my former plant making cryogenic liquid and sure enough, same thing, none to be found. Miles and miles of welds and no acetone to be found.

If there is any glue residue or something of a hydrocarbon base on your metal, then by all means wipe it with acetone, but other than that, can anybody tell me what this practice accomplishes. Maybe I'm missing something about acetone that others have picked up on.

Sorry, rant's over, carry on.

Len

Len I believe it's just a factor of welding clean parts, most pipe that I've worked with has been processed in a saw with coolant, grinding and such. All this needs to be removed. I typically would use isopropyl alcohol, much cheaper and safer to use.

[melsdad]

Thanks guys!

I know a welding cart is a non critical part. But I want to start out with good preparation practices. I have been trying to clean everything I weld as best I can. I want only me, to be the major variable as to what my welds turn out like.

The material I have is definitely free of oil other than the oil from my hands. I will make sure all of the loose dust and sand is off the material and start to weld.

[MosquitoMoto]

Definitely sand/grind that rust off.

I undertook two jobs in the recent past (both just mild steel), one where I had no opportunity to clean the steel other than with an acetone wipe, the other where I ground off the scale, prepped properly and then welded.

The results were very different. The 'dirty' steel, which honestly wasn't very dirt at all, gave sparklers during welding, brought impurities to the top of the puddle and returned a crusty weld bead. The clean stuff welded like butter and the end result was a shiny, even bead.

The dirty stuff will weld, just nowhere near as well. Tig loves clean.

Kym

If I understand the question, he is asking about wiping it down AFTER sand blast. If you have a good blaster that should be fine, however you can try a wipe and look at the rag/paper towel, if it looks clean then no need to continue.

Not seeing the condition of the angle, it could be if the rust is too heavy then a quick hit with a flap disc after blasting would be preferable, if you're unsure try a drop piece.

Hey...are you assuming that I read the OP's post properly?

(Must stop juggling work on one screen and WT&T on the other!)



Kym

[big gear head]

I weld a lot of stuff after sandblasting. I usually take a stainless steel wire brush and go over the area to be welded to remove any sand that might be embedded in the metal and dust from blasting.