[Car-Cray-Z]

I'm hoping one of you seasoned pros can offer some clues for the less experienced people, like me.

I'm not completely sure what details matter vs what don't so forgive me if me trying to be too detailed becomes annoying.
I use an Everlast 350amp TIG machine and custom water cooled torch rig. 3/32 2% Lanthanated tungsten and a #12 Furick cup. I've played with my settings over the years and am all but positive I've got enough argon flowing.

One case: A used stainless fuel injector rail (assumed to be 304) was brought to me where he wanted a mild steel 6AN fitting welded to the end. I set up a little rig to back purge it, sealed off all the holes and pushed argon through it during the process. I am in the habit of using material dedicated brushes and Roloc style discs to grind/clean and prepare areas to be welded. I typically wipe it down with clean paper towels and acetone, before and after grinding and or brushing the areas. I welded it up using 309L filler. After welding, I reinstalled the fuel rail and discovered it was leaking. I ended up chasing this leak for a few welding sessions but it was immediately, abundantly clear that I had a contaminated weld and while I'm aware of carbon steel to stainless issues, I've done well with is using 309L filler in the past, so I believe this is contamination from the the gasoline, aka hydrocarbon/carbon I know the rule....if you always do what you've always done, you always get what you've always gotten so I stopped chasing it and am asking for help from the seasoned pros.

I have also experienced this with issue when butt welding aluminum in the past.

I read about this type of contamination and recall something along the lines that under the arc, in the puddle, the carbon liquefies and runs throughout the weld, bridging the inside to the out. Grinding it down with new discs, cleaning and re-welding didn't help. I thought about trying less heat, keeping my gap as tight as possible to get the puddle with lower settings. Every time I hit it with the torch, new leak/s show up. I've had this happen once before with an aluminum fuel rail and an aluminum A/C line that I tried to butt weld. Ground it all the way back down, cleaned and welded it up a dozen times to no avail. For the record, the cure for the AC line was to cut an aluminum tube with an ID as big as the OD so that I wasn't welding over something exposed to the ID, where oil had been.


So rather than chasing your tail, once you discover this contamination has occurred, what's the method for solving the problem?

[BillE.Dee]

Not too good at the stainless deal...yet.....HOWEVER, I do know you want to be very careful when welding the A/C lines. If there is any freon lurking around, you can burn it, convert it to PHOSGENE gas and then you won't have to worry about welding. this might be too much to the point but I really don't know any other way. Please, PLEASE be careful.

[Car-Cray-Z]

I know that's true of chlorinated brake cleaner. The lines are always blown out and cleaned and I can't see it as being too easy to keep a chlorinated gas around while welding but you never know. You damn sure don't want to be wrong, I guess.

[tweake]

so I believe this is contamination from the the gasoline, ............ aluminum fuel rail and an aluminum A/C line that I tried to butt weld.

So rather than chasing your tail, once you discover this contamination has occurred, what's the method for solving the problem?

often this is due to oil soaking into the steel. AC lines can have oil in them and not uncommon for motor heads to run a bit of 2 stroke in the petrol.
typically cook it out and use solvent to draw it out. grinding won't help because you just go down to more contaminated metal. think of it like welding dirty oily cast alloy.
sometimes you can get around it by brazing rather than welding.

[Oscar]

First thing I would have done is to check if it was really 304 stainless, which I'm betting it's not. Does a magnet stick to it like it does to steel, or does it feel only the tiniest bit magnetic? Most OEM fuel rails are not SS, I would be willing to bet. Perhaps nickel plated steel or something along those lines. In any event, I would simply grind out/off whatever I could, and then weld the rest up with either Super Missile Weld or Hastelloy-W rod. Coming in at a close 2nd place would be ER312.

Oil soaking into STEEL? I don't buy it. Into aluminum castings, yes, but into solid steel, never seen it.

[tweake]

Oil soaking into STEEL? I don't buy it. Into aluminum castings, yes, but into solid steel, never seen it.

not uncommon. especially if its been heated.
afaik its actually a finishing technique for steel.
its also something you find when your using scrap to practice with. crap thats been lying on the floor/bin in a puddle of oil for a long time. clean it all you like, it still smokes when you heat it up.

[Car-Cray-Z]

First thing I would have done is to check if it was really 304 stainless, which I'm betting it's not. Does a magnet stick to it like it does to steel, or does it feel only the tiniest bit magnetic? Most OEM fuel rails are not SS, I would be willing to bet. Perhaps nickel plated steel or something along those lines. In any event, I would simply grind out/off whatever I could, and then weld the rest up with either Super Missile Weld or Hastelloy-W rod. Coming in at a close 2nd place would be ER312.

Oil soaking into STEEL? I don't buy it. Into aluminum castings, yes, but into solid steel, never seen it.

It's definitely stainless. I'm pretty comfortable and experienced with figuring out materials. I'm not a seasoned professional welder but am quickly approaching 50 and dealt with various materials throughout my life. I still confirmed with a good magnet.
These are OEM GM rails made by Bosch. Some years were coated steel and most of the later models are stainless. I thought about brazing but hoped it could keep it looking good with stainless filler. I've got 347 filler but no 312. I guess I'll order some up.

There was a time that I might have agreed with you about oil soaking into steel, but then one day I was heating up a timing gear to install it. I cleaned it with acetone or some solvent and then hit it with a propane torch. I soon noticed it "sweating" oil. I wiped it off and continued heating it and the oil continued to sweat out. The next part I can't say for sure is true but when I asked an oil engineer about this he told me that the zinc and phosphorus and other additives that are in the oil help it impregnate the metal this way.

[TraditionalToolworks]

It's definitely stainless.

I don't think Oscar doubted that, just that it was 304.

Whether the oil is impregnated or just on the surface which wasn't cleaned, it could still cause the same problem.

Sounds like you cleaned it well before you started welding?

[Poland308]

All oil and gas will soak into steel. It’s porous. I’ve welded on lots of diesel lines for boiler piping. Any old oil pipe is always contained. You can burn most of it out if you get up above a 500F preheat. Keep it below dull red, that’s in the 900F ball park.

[Poland308]

I bought some 312 for using on some questionable SS I ran into. It welds in a lot like 309 but it flows buttery smooth.

[Car-Cray-Z]

It's definitely stainless.

I don't think Oscar doubted that, just that it was 304.

Whether the oil is impregnated or just on the surface which wasn't cleaned, it could still cause the same problem.

Sounds like you cleaned it well before you started welding?

With adding the comment about the part being possibly plated, I guessed that his thought was that it was mild steel.

I certainly tried to clean it well with a roloc disc and acetone. What I struggle with is now that it's got these microscopic fissures or worm holes in it, is there any saving the part? I tried various things to see if it helped or hurt the situation, various levels of heat, one trying to hit it hard and fast or less heat and moving more slowly in small spots where I knew it was compromised. Tried exiting out very slowly versus hitting it and quitting it. No matter what I've done so far, it continues to leak. I plan to grind it back down, acid dip it, rinse it, clean it with acetone and weld it again to see if it arrests the carbon that's propagating throughout my weld. I'll report back if I accomplish anything.

[sschefer]

First, yes, I have run into this problem and just like you I struggled to find a cure. I knew the trick for bonding HDPE plastic was to pull the mold release to the surface using a propane torch. Thinking it was oil contamination I tried that and it sort of works but was not the solution. After a while you start to think really hard and often deep into the night and at a little after 2am I woke with Helium on my mind. I wrote it down on my little pad on the nightstand and in the morning I looked at it and it kind of made sense so I tried it and it worked.

OK. so I've told you what worked for me but in no way am I absolutely sure it will work for you. Helium is expensive today and you need 99.999 % pure not Balloon gas. If you have helium now then give it a shot and see what it does but it you don't have it, braze it with silicon bronze rod, it's more than strong enough and is an acceptable and often expected solution on fuel rails.