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  • Stainless oil lines

    I was looking at building some 3/4 and 1" oil lines for a race car. I found some .049" wall tubing I can buy in 6 foot lengths. I probably have to go 10 feet , just wondering if this seems like a good idea. I would have to make a few butt welds and flares on it, the tube is labeled as "soft" so I'm assuming it's annealed. Will this weld ok if I back purge it ? I don't want anything be coming brittle.

  • #2
    I had to do the math...1/8" = 1.25, 1/16" = .063.
    .049...That stuff is pretty thin.
    Hmm..?
    Your going to GTAW that? Good luck. Depending on your welding skills it will come out fine and dandy or oh crap I should have seen that coming?
    Well I know it's do able. Steady hands, react quickly, move quickly around the axis kind of thing...
    Or steady hands, slow and steady wins the race, and one drop at a time kind of thing.

    Butt welds require a tight fit. While you can dress taper the tungsten, smaller is better in this case.
    Flaring the connection while offering up a material waste to aid in joining, will also make the connection slightly more rigid?
    You mention back purge. It's an oil line. I'm sure it will be happy you did, but for all practical purposes, probably isn't necessary? Tight enough fit and the weld can be done autogenously...In that instance a back purge will help a bit, but it will come down to skill more then a purge back pressure to prevent excess heating, fall through and filling holes that blow open and trail off.

    Now you didn't ask for my opinion, if you had I might suggest alternatives to GTAW or the joint design. For instance, sliver brazing or just plain brazing. Maybe taking a small section of tube to be split so it's squeezed/compressed to slide inside to act as a sleeve? Expand and socket the joint so it's a fillet over a butt?

    As far as making things brittle, I'd worry more about leaks. But brittle comes from heat and rapid cooling. If you think about it, the material is .049" thin. How much is missing to make a solid piece? Because that how much weld is actually needed.

    I might suggest Stainless GMAW wire for filler? Nothing worse then trying to melt a filler rod that's to big for the material. Good luck. Post a picture. And my comment about silver brazing, or low temperature brazing, that's a solid bit of advice. Not the most common, but still solid.

    All that said, I do have some limited experience on thin wall stainless, the basis for what I shared. Others may have more to offer. Like a compression connector type fitting and no welding? Just a thought?

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    • #3
      For a race car? I would absolutely back purge it, otherwise that sugaring will eventually crack and make you sad, and probably on race day.

      That tubing isn't too terribly thin, I've done it for the drag cars in both stainless and aluminum.

      Outside of the back purge, you'll be much happier if you spend some time on your tungsten. Super sharp and polished point and it'll make your day much happier. And I mean polished, not ground on bench grinder, not zipped across a disc sander, polished. And did I say sharp? You'll see what I mean when you do it, totally worth the effort.

      I would also use a gas lense, which I do for most things, especially stainless.

      What kind of race car?

      My favorite saying, "racing's stupid"...

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      • #4
        Back purge for sure, as others have said, fitup needs to be near perfect, clean the tube inside and out, pay attention to details. Don't know what your TIG experience level is, post back with some photo's.
        Richard

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        • #5
          Originally posted by fullrace View Post
          I was looking at building some 3/4 and 1" oil lines for a race car. I found some .049" wall tubing I can buy in 6 foot lengths. I probably have to go 10 feet , just wondering if this seems like a good idea. I would have to make a few butt welds and flares on it, the tube is labeled as "soft" so I'm assuming it's annealed. Will this weld ok if I back purge it ? I don't want anything be coming brittle.
          I would not do it to my race car.
          Reason being if the joint is 4 ft back in the line (6ft + 4ft = 10ft) you pretty much don't have any way to clean the back side of the weld or even know if you need to.
          I would either buy a longer piece or the proper fittings and plumb it correctly.
          In my shop we do this style of work on 150+ mph offshore boats. Too much money at risk on those things just to save a buck or two on fittings.
          Not a good place to be learning IMO (unless you are rich) Exhaust....sure, water sure, Fuel...maybe sorta (but not really)
          Oil...Heavens no!!!
          Last edited by FusionKing; 11-21-2018, 07:45 AM.

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          • #6
            Sounds like the sanitary welding we do, perfect straight cuts, minimal deburr (no bevel), clean well, purge and fusion weld. Do several practice welds on short pieces so you can see your penetration or lack there of. With good purge inside will look as good as or better than the outside. This part was practice for a recent job. Material is 6" x .110 316 SS the numbers on the part were the amp settings used. On .065 wall we run the machine at 67 amp's to get the right penetration. So .049 would be around mid 50 amp range. We run flat out full pedal when doing fusions like this. The sample in the pic was done walking the cup but we also do it free hand with no weave.

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            • #7
              I agree that I would get a longer piece of material and not put additional welds where they were not required. But I would trust all the welds done this way to never fail.

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              • #8
                Kuddo's, goes to the man who posts a picture. And credit to the guy who practices enough to get that good or rather that consistent.

                As Clint said in Dirty Harry, "A man has to know his limitations".

                It doesn't shame me to admit I'm not that good. I'm not. Not enough time spent in practice and play with thin wall stainless that would come close to meeting that level of consistent repetitive movement...
                Opportunities like that don't exist for all of us.
                Maybe that's why there is a shortage of skilled GTAW welders?
                Sad truth is, not everyone makes it to be a rich surgeon, some just have to be doctors and practice the craft.

                Now it's old age, failing eyes, big bellies, loss of muscle and less steady hand control. The good life. I remember when, and I still wasn't that good. Maybe I was but no opportunity to show it? I remember looking at the welds on the rocket boosters at NASA. and thinking, that weld made it into space?

                Fixed position or roll welding makes a difference, If I'm rolling things I show improvement. Lol… Depending on the power source, it's easier on a Dynasty then a Syncrowave too control the arc, it's behaviours, and the resulting weld appearance. If I have a claim to fame it's being able to keep the same level of consistent between both power sources. Talk and chew gum? I can do it, just not for long.

                I think there is a big difference in welding between a 6" and 1" tube. If there wasn't, orbital GTAW would be so popular. But that is tempered with knowing if you got it, the difference isn't that great either?
                Welding a .110 wall thickness and a .049. Something about one being more forgiving comes to mind? Still both can be a challenge. Nice to see that showmanship. A person can gain a lot of knowledge if given the free rein to play and discover things out. If nothing more then discovering ones limitations.

                The difference between a oil line on a Friday night drag car and a 150 mph speed boat. One makes Hot Rod Magazine the other means you're calling the coast guard and treading water.
                The best advice was a longer piece or proper fitting at additional expense. Why is two fold. Risk is one, appearance is another.

                Not unfamiliar with walking the cup, not that I was ever a master at it either, that to me is a weave. It's no longer a straight path it's a waddle of a arc walk resulting in a wash and flow. But honestly, those welds were sewing machine tight in consistency. Must be a heck of a dancer with that kind of rhythm.
                That isn't however my point. My point is, if the two edges are fused it won't leak. If enough metal is fused on top no matter the depth of penetration, it won't leak. When we get past the leak thing, we are left with strength in service conditions.

                Now it was mentioned the concern of brittle failure. Not blowing a rupture because of high pump pressures, brittle failure. Could be good cause for that concern? Vibrations and frequency...? Thermal shocking to a brittle zone? Oil everywhere. It's going to leave a stain.

                I wouldn't be afraid of welding it, I'd be afraid of messing it up when I welded it. But it's doable.
                Good advice on the tungsten and sharpening. A focused arc makes a world of difference. Seeing it however is priceless. Clean lenses, a cheater doesn't hurt, and a few dry runs of the motions you'll go through. Good luck. I'm guessing your going to try it.



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                • #9
                  I concerned about the crap getting into the engine bearings.
                  That's all.

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                  Miller Dynasty 700...OH YEA BABY!!
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                  Miller Dynasty 200 DX "Blue Lightning"

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                  Miller 30-A Spoolgun
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                  • #10
                    Why go this route instead of using the more conventional braided lines with AN fittings?

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                    • #11
                      All the more reason to avoid the risk and use a longer length or a compression fitting to join the two together as you mentioned.

                      Having said that...The trick will be welding it to prevent excessive heat and melt through if he attempts it to save a buck?
                      My choice would be small tungsten, blunter point, low heat.

                      Having spent some time cleaning parts, removing casting flash, smoothening cast surfaces, doing things on a low buck budget, my assumption was sugar boogers weren't the issue or worry as much as actually doing it to prevent the occurrence. It was a valid point however. You don't want that hardness floating through the system.

                      To explain the added pictures, because everyone likes to view pictures, it was a Cali. E Bay purchase. 91 5.7 and 6 speed. Nothing really race or high tech, or to do with the oil line thing. Just take it apart and fix the problems.

                      But it was head gaskets as the primary issue for tear down, lacking regular maintenance, would be my guess? But I took a chance regular oil changes were done as it was I was told, a runner? Tearing it down, seems I got lucky?
                      If it wasn't for the oil filter, screen on the oil pump, heavy particulate settling in the pan bottom, I'm sure other issues would have been found. But most folks do change oil on a regular basis. It's back together time will tell.

                      What you don't learn from the experience of others you discover on your own...Hopefully he posts the results?

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                      • #12
                        Use SS braided lines. Do not use rigid tubing-for a lot of reasons. What kind of race car are you dealing with here?

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                        • #13
                          You know...most days I go for easy. Not costly, pretty, functional. Easy. Welding is.
                          Somewhere after easy is functional. Followed by pretty, then cost.

                          Now I'm no expert on race cars or hot rods. But I did save two 3 ring binders of tech articles and how too do before giving away the 20+ years of buying. Now you might think, what a waste but, the guy who took them was looking to plaster his walls with cars. Win/win.

                          The point is however, while you might think there is a lot of reasons for not using ridged tubing, race car or other wise, You don't see rubber braided ss covered pipe lines being built? Unless your in Texas. There building pipelines. But not out of ss braided line. There's is ridged.
                          While there is a time and place for easy, some times you have to go with functional, pretty and costly. Easy is at the bottom.
                          But that to depends on the service needs. Those costly and pretty SS braided lines have a place and purpose.

                          Like you I'd like to know more?

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                          • #14
                            Not uncommon to see oil or fuel hard lines being made out of 304 annealed SS in some racing applications...............but no one cuts and welds it .......it's all done via a single or double flare using the correct 37 degree AN or JC 45 degree fittings........as far as bending it the stuff is annealed and bends quite nicely with the proper bending equipment.......you will also need to find someone with the correct sized flaring tools.......Stainless hard lines should also be hung using the correct vibration free hangers........... also in a normal application a short run of SS braided line is used to isolate the hard line from the vibration of say a motor............stay away from welding on it as it just makes the joint brittle.
                            Last edited by tarry99; 11-24-2018, 10:43 PM.

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                            • #15
                              Sorry I didn't reply on this, I guess I really was just asking if this is the proper way to do it. I was more looking for the "yeah sure that is normally done and should be no problem" , but it sure seems like i should probably just try and find a longer straight section. I was just basing this on what I found off of Mcmaster Carr, I will check with some local tube suppliers and see how much longer lengths may cost...

                              Part of the reason I was trying to run something different than braided line was because I was thinking -16 line was going to be a fair bit larger than running tubing. But after I looked its under 1.200" so maybe I will just go that way. I have made many lines out this way , just looking for other possibilites/a "cleaner" option..

                              The car is a 66 mustang with a cup motor.

                              Thanks for all the replies , much appreciated.

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