[miketigseverything]

Hi guys, I have a question about cleaning aluminum pipe for oil delivery trucks. Where I work, we often build new trucks, and or re pipe old trucks, and it often requires a mock up and tack phase, then we remove it and tig it on the bench. Lots of times there is a good amount of grease, oil, and petroleum products that get between fittings, elbows etc. We've been using acetone, an aluminum cleaner/ brightener made by weldmark, and brushing with a SS brush with decent results. My question is, there always seems to be some crap that floats up into the puddle and stays there after it's cooled. Is there a better way to clean these pieces to got great results in one pass? Thanks for any info!

[Braehill]

Mike,
First off, welcome to the forum.

I would think that acetone would break down anything with a petroleum base. MEK is another option for petro based contaminants. Aluminum is known for holding oils in it's pores and they find their way into the welds. You can try going over it with justs enough amps to get some cleaning action to bring some of this to the surface and then wipe it a second time with a solvent.

Most of the piping on oil tankers are thinner pipes and shouldn't be that hard to introduce enough heat to boil some of this stuff out. You could even try an Oxy/Act torch on the used piping, anything to try to get the residual contaminants out of the pores.

There are others here who work on petro tankers and may well have a better solution so give it a little time for them to respond.

Len

[massacre]

I weld on oil trucks too and it can be in a real pita to remove the oil. A lot of our newer trucks use SS for the product piping which doesn't have the same problem.
There is no secret way to remove it that we have found, we prep the same as you do, acetone and wire brush, etc.

[noddybrian]

Done a little of this sort of work though not recently - if the parts will fit then hot tank them with a dilute alkali cleaner - if you can boil it in an agitated tank that's great - if not steam clean everything first - then carry on as you did before - some contamination will always come out but the longer you can boil a part the better it welds in my limited experience - if needed do a run with the machine set as much electrode positive as you can without melting the tungsten - but not quite hot enough to weld - allow to cool if part is small & becomes heat soaked - then set balance to your normal setting & weld - some crud is so bad that even then you may have to dress the top & re-puddle over what's there - some people do a very small root run with small filler to allow room for a 2pass weld to allow for this if the material is obviously going to be dirty.

[miketigseverything]

Thanks for all the input guys. What I usually end up doing is what noddybrian said, and that is to run a small bead first to float the stuff to the top, re brush and wipe with acetone, and run a larger bead over the whole thing. I didn't know but there was another process that I had missed to cleaning. All good stuff. Thanks again!