Hey Gang: I'm new to TIG - but I must say, love the machine! Anyway I'm going to be making my own custom headers for my 392 Hemi in my 34 coupe. It will be a heck of an experience -- so I'd like to do it once and do it right. 1) Using Shielding Gas to Fill the Pipe: I've heard that the best way to help the quality of the welds on the INSIDE of the pipes is to plug both ends of the tubes and flow some Argon on the inside of the pipe -- to shield the inside while you weld the outside. I imagine I'd need a little exit hole on one end (what size?) - what CFM would I setup the flow-meter for . . . can't imagine it would matter that much. Anybody done this? 2) Stainless Tubing: I've decided to bite the bullet and order stainless mandrel bends - then weld everything up. What stainless rod would you advise to use for 16 gauge tubing? (Was going to use steel - but thought about them rusting out over time and that you can't rework/fix them once they're chromed . . . stainless gives me more options.) 3) Tungsten: I have been "practicing" on regular 16 gauge steel -- using a small electrode .040 . . . seems to work well. Any thoughts on using .040 versus 1/16 electrodes? Thanks . . . as a newbie . . . I have more questions than answers! Dale
True purge welding involves more than just sticking a gas hose inside the tubing. I did it for several years on food grade stainless tubing, where the inside of the weld looks pretty much exactly like the outside. This takes more than just gas on the backside of the joint, it involves a different technique with the torch itself. You have to do something to break the surface tension on the backside of the puddle. Some do it with the "pulse" setting on the TIG, others, like the Pipefitters, do it with a technique called "walking the cup". (Commercial orbital-welding machines do it by the pulse method) You don't need a food grade joint in your situation, but you can achieve 100% penetration easily enough by taping off both ends of the tubing, poking the gas hose in one end, and popping about a 1/4" hole in the other end. When you poke the gas hose through the tape, wrap a little more tape around it, to help keep it from drawing oxygen in. The hole in the other end is to promote flow, while still keeping a small amount of pressure inside the tubing so no oxygen comes in from that end either. Depending on the amount of tubing involved, I usually start the gas flow for a few seconds at around 30 on the flowmeter. Once I think the oxygen has been replaced with Argon, I turn it down to around half that, and start welding. *edit* As for filler rod, purge welding is best done with a very small gap. On Food Grade jobs, no filler is used, the joint is fused. In your situation, look and see if you can get .040 filler rod. If you get a good fit on your joints, .040 will be just about right for making a small, pretty bead.
I'm not a TIG expert but I have trouble with Stainless rusting at the weld. I have been told several times why this is but I cannot seem to eliminate it. Just thought i would mention that in case you wanted a rust free header. Best of luck
Several reasons why this can happen. Using a carbon steel brush, or a stainless brush that has been used on carbon steel, to clean the joint or the bead can contaminate the surface. Using a lower grade stainless as filler can do it; we don't use anything lower than 316L. Grinding wheels that have been used previously on regular steel can contaminate stainless. Part of the reason sanitary tubing is "fused" is to eliminate the possibility of the filler rod being made of a lesser material than the tubing.
HOORRAAYY! An informative thread!! Do you guys use two bottles then? Would you use a higher setting on the regulator to purge larger diameter tubing?
I took an aluminum base ball bat, cut it down capped one end with a fitting. The small end will stay in the tube with a little twist. Put a "Y" on my flow meter with a simple valve. Cap the other end of tube with hose clamp and piece of inner tube with small pin hole. Been using this for about 15 years. Hope this helps. Ted
Use a steel hose clamp w/windows cut in it for alignment. Use a square **** no bevel. Use lots of tacks. When you see the dot (silicon / slag) start to move around the puddle you are getting 100% penetration. You must have a vent with the purge in order for the oxy to escape. Most wire wheels are 400 S/S and will cause rust. I prefer a 1/16 tungsten for 30 to 90 amps.
We use 3M roloc pads with a medium grit to clean the metal before welding. We use .040 or .049 fill rod with a tight fit. I use a 1/16" tungsten at around 75 amps but that's mainly out of habit; I need to try an .040 electrode someday. Hank
Solar flux mixed with rubbing alcohol to a wet paste can be used on the inside of the pipe to shield the backside from contamination. Makes the back side of the weld bead very flat. Worked for me. Hell of alot easier than messing with gas flooding.
I agree with born2late Solar flux makes stainless headers a lot easier. Makes the inside of the weld nice and smooth and give a good 100% penatration. No "stalag***es" on the inside, doesn't comsume excessive argon, which if you have bought a bottle lately is getting damn expensive. BTW what kind of stainless tubing are you using. 321 is the perfered, made several sets of turbo headers with it. I also like to use the 1/16 tungsten never tried the .040 on .065 tubing. Rex
There is a logical metallurgical answer. And much more likely than slight contamination. You are getting senstization. In short, the heat from welding causes the chromium (what makes stainless corrosin resistant) to form with carbon and make a locally depleted chromium in the heat affected zone (HAZ). It makes the HAZ area next to the welds to be less corrosion resistant, and they get light rust. It happens in the region that is 600-1200 F temp range. Using low carbon staniless (such as 304L, 316L, the L means extra low carbon) helps minimize this sensitization problem. To fully eliminate it, you either need full post weld heat treatment to put the chroium back into sloution, or use a stabilized grade. Stabilized grades are 321 or 347. The stabilized grades have ***anium or niobium which are stronger carbide formers and keep the chroium from forming the chromium carbides.
a lot of good info here, but I would also suggest about 1 amp per thousanth of electrode, +- about 20%. So a 1/6 is good for around 60 A +-. If you go to high, you will melt it (90 A on a 1/16 electrode? I havent had any luck with that) if you go to low, you will get an unstable arc. The rusting may be caused by, like stated above - the chromium coming out of the stainless. If you over-heat the weld zone, you can burn it out as well (whitish powder magically appearinng). Is 347 avaliable in SS tubing? it's kinda an odd alloy in my experience.
Great information - more than I ever expected! I spent some time 'learning' with 16 gauge steel yesterday -- used both .040 as well as 1/16 electrodes, liked the .040 a bit better. I ran about 55 - 60 amps -- on a Miller Maxstar. Great idea on the aluminum bat -- was pondering this exact problem yesterday. I also liked the idea for using "cut out" hose clamps for alignment during tacking . . . a great idea. Couple More Questions: 1) 304 versus 321 Tubing: I know that 321 is a better grade, but is it worth the price difference for a header application? I can see a turbo application getting potentially hotter -- how about a blown/gas car? 2) T304 versus 304L: If I have the choice between the two - should I use the "L" . . . as a reply mentioned this as "low carbon" -- might help the joints. I have not looked up what "T" means. 3) Stainless Collectors: I see some wild *** prices out there -- anybody know a reasonable manufacturer whose product and quality you appreciated? 4) Flange Thickness - Welding Tubes to the Flange: I'm new to TIG, but am thinking that it is going to be hard to get the heat penetration needed on the tube-to-flange joint -- seems that a 1/4" flange would be easier than 3/8". If I bring the tubing through the flange (like most header mfgrs do), and I'm using 16 gauge tubing and a 1/4" flange - what tungsten diameter and amps would you recommend? Any "tips" on how to get a good weld here and not over heat the thinner tubing? With just a few hours practice, I can weld the tubing-to-tubing **** joints pretty well - but am concerned on this end of the pipe! I'm more than willing to practice, but I'm lacking the experience that helps my evil ways! Thanks so much . . . as I get into this project, I'll post as many pictures as possible -- may help the next "lucky" guy who decides he has to make his own headers to get what he wants! Dale
Good info for sure. Having done lots of the same type of work in the past, (food grade fluid transfer) I can't add more than what's been posted, other than the hose clamps work in tight areas but I prefer useing visegrip tubing clamps for quicker and more accurate joint allignment. When you get to the flanges I would use the 3/8" material, also where the tube goes through the flange on the head side you need to bevel the i.d. about 1/8" and have the tubing protrude about 3/16". When you weld up the joint you are going to fuse the two together useing the tubing as your filler. When you do this it will fill your beveled area getting good penetration. When your done welding all thats needed is to run the flange over a belt sander to true up any warpage. The rusting at the HAZ can be minimized by just useing a s.s. wire brush by hand and remove all bluing from the weld area.
I can't add anything inteligent about technique... but here is where I get SS bends and collectors for my headers. http://www.burnsstainless.com/ Not cheap, but very nice. if nothing else go poke around their site. They have several helpfull do***ents about building headers, from theory to practical. Eric
Now, why would you get mandrel bends from Burns Stainless when you can get them, including custom bends, from a HAMB Alliance vendor at a lower price? Just ribbing you a little. Check our link below. Hank
Depends on where we're at. In the shop, we use two bottles because we are usually doing quite a bit of it at one time. In the field, we use a "Y" type splitter off the bottom of the regulator. You have to turn the regulator up quite a bit when doing this, but it saves having to drag two bottles around with you. As for the bigger diameter tube, I guess once it got to a certain point you might have to add more gas, I don't really know. The biggest tube I have had to purge weld was 4". I did it just like the 1 1/2" to 2" tubing that we normally weld. Turn the regulator up pretty high for a few minutes until I think its pushed out all the oxygen, then turn it back down and start welding. As long as you have both ends sealed up good, with just a small hole to induce flow through the tubing, you shouldn't have to add much pressure. Most of what we weld uses "tri-clover" fittings, so we have a set of end caps that we have drilled and welded a piece of 1/4" tube in. Whatever size pipe we're using, we just clamp the end caps on each end and attach the hose to one of them. Temperature-wise, the puddle should be on the verge of "falling through" and added gas pressure can help in this area. It helps support the puddle, but too much pressure will actually cause the puddle to blow outward. One way to judge temperature and gas pressure is by paying attention to what the puddle is doing. Too high temp, and too much gas pressure will make your bead raise up slightly, kind of like a mole tunnel, or it can blow out the puddle. Too much heat and too little gas can cause the weld to sag, and sometimes let the puddle drop out. Too little heat or too fast travel speed will obviously leave you with less than 100% penetration. Done correctly the inside of the bead will, literally, look just like the outside of the bead. Sometimes the inside actually looks better. In a Food plant environment, they really don't give a **** what the outside of the tubing looks like, as long as the inside meets their specifications. One thing to bear in mind as I explain this, is that "sanitary" stainless tubing is where my experience with purge welding begins and ends. Sanitary tubing is roughly 16 gauge, regardless of whether its 1 1/2" dia., or 4" dia. I'm sure you can probably purge weld heavier stuff, but I personally have never tried it. Purge welding by hand is somewhat of an art, and it takes quite a bit of practice to become adept at it. Best way to practice would be ****ing two pieces of s**** tubing together then cutting it apart to look at the inside after you're done. Trial and error until you get it right. And fit-up of the joint is crucial. If you have more than a hairwidth of gap, its too much unless you plan on using filler. Different people weld with different amperage settings because of differences in travel speed, and welding style. Welding in field conditions with a portable TIG that has no "pulse" setting, I run in the neighborhood of 80-90 amps, weave the torch head in very tight, fast circles, with the tungsten pointed straight down at the bead, while turning the tubing with the other hand. The fast movement with the torch head helps to break the surface tension on the backside of the bead because it adds sort of a jiggling motion to the puddle. An Orbital welding machine does this by "pulsing" the amperage as it travels. Orbital welders do just about everything for you. They cost around $10 grand though, and only work for straight pieces of pipe. If you are welding together a manifold, or a "T" joint, it doesn't do you much good to have the thing anyway. If I'm in the shop, I put the piece to be welded in a small turntable that has clamps like those on a lathe. It is made especially for turning at the slow speeds needed for purge welding, and can be adjusted to run vertically, or horizontally. Our big TIG welders in the shop have an automatic pulse setting built in. This allows you to simply hold onto the torch and guide it in a straight line. The turntable and the welder take care of the rest. Thats almost like cheating though... The Pipefitters I've watched, do it with a different grind on the Tungsten, more amperage, and with the cup actually touching the pipe at a pretty extreme angle. They flip their wrists back and forth at a high rate of speed, while the cup never leaves the surface of the pipe. They use that back and forth wrist action, along with slight forward pressure to "walk" the cup along the joint. If you are watching them do it, it looks like they're really going to town on something, torch lead flipping back and forth like a wounded snake. Then you walk over and see that all that movement is producing a tiny, 1/8" wide bead. Walking the cup produces a bead that looks like a stack of dimes, but the dimes alternate from left to right slightly. Its easy to tell what style was used when looking at the finished bead. When I purge weld, my bead looks like a stack of dimes, but in a straight line instead of alternating from side to side like theirs. The whole idea behind all this work, is to produce a bead that leaves no holes, gaps, or cracks on the inside of the pipe. That way, bacteria, and the cleaning solutions used in these food plants have no place to hide. The added strength of the joint from the 100% penetration is actually secondary in a food plant. If you are doing all this in a food plant there are still other factors that you have to adjust yourself for, even if you have achieved 100% penetration. Food plant weld inspectors want to see a gold, or light blue HAZ on the inside of the tubing, or preferably no color change at all (yes its possible). This is done by fine tuning the flow of the gas, and your travel speed. When you have travel speed and gas flow adjusted correctly to the amperage you are using, the gas flow will draw the heat away from the inside of the bead fast enough to keep it from coloring. The reason food plants are so particular about this is because of the chemicals they use to clean the tubing between batches. If you overheat the weld, it burns something out of the metal in the HAZ, and the cleaning chemicals will attack the metal in that area. Eventually, the joint will fail. The company I work for has two sides to it- HVAC, and Plant Fabrication. I TIG welded in the plants for about 8 years, until I got so sick of it I was ready to quit my job. Now I work on the HVAC side of the company, and to be totally honest, it wouldn't bother me a bit if I never touched a welder again...
I use two bottles - two regs. Take a pc. of aluminum round bar ( same dia. as your header tubes ) - drill a .437 hole all the way through - 1/4 NTP pipe tap one side - 1/4 NTP to argon hose adapter for a conection. Radator hose ( I.D. ) same as your tube & two hose clamps complete your conection to argon bottle. Op side of tube - another peice of rad hose, two more clampers & another aluminum round - this one has a .063 hole drill through it. Clean all your joints with SS brush then wipe with Acetone. Set purge argon to 15 cfm & let it flow. I use 3/32 tungstun for 16 G SS - NICE long sharp grind - but this is a welders preferance thing - large dia gas lense - ( I also use Syvania 0range Cerated Tungs ) 308 SS filler rod .035 & .045 dia's is what I like for 304 tube. The flux deal works, but no were near as nice as the gas purge set up ( my opinion ) Burn's builds a ausome collector - best value you can find far as I have seen & they have a un-matched tech department that can help you in designing a proper collector for what your building.
So do we. We weld everything from 24g to 3/8" plate with 3/32" tungsten. I grind the point differently for anything over 1/4", but other than that, I have never seen a reason to have 2 or 3 different sizes of Tungsten. We also only use three sizes of filler rod for that material range. .040, 1/16", and 1/8".
Using TIG-P Pulse Options: Okay . . . now I'm really going to show how green I am! I decided to learn TIG welding (did lots of stick welding over the years and quite a bit of Oxy/Ace stuff) - as I figure it is one skill that will save me tons of $$$ in the long run (building from the ch***is rails up) - and I can do things my own way. So - I saved my $$$ and decided between a Miller Maxstar DX and a Dynasty DX . . . decided that I'd be welding aluminum so little, that saving $1000 was a good thing (plenty of other welding places to spend it). So here is my question: Using the Pulse Option -- Settings: My Maxstar has the TIG-P capability - though I've never attempted to use it (only had the welder 2 weeks). So - for welding 16 gauge tubing, should I think about using the pulse option? If so, what would be some good settings for 16 gauge mild steel versus stainless -- anything different in the amps settings? Thanks again - appreciate you putting up with a TIG green bean!
Best advice I can give is......TRY IT..! Move the dials around & see what happins. Experiment....test....compare your results then try some more. Thats the best way to master a machine, or a process.
I worked for 6 years as a design engineer, designing Waste Water Plant and water Treatment Plants. Both of these type of plants use lots of Stainless Steel. My experience is that 304 works great in submerged applications and not so great in non-submerged applications. On the other hand 316 works great in both submerged and non-submerged applications. So my answer to the question of paying the price difference for 321 verses 304 for a header application would be to use the higher nickle content 321 for this application. Just my 2 cents........
I would like to add that I was recently holding a real nice set of stainless hemi flanges with 3 or 4" of pipe already swedged into the rectangular opening. Don't know who made em, but trying to find that company for my hemi's headers. Would save tons of time over bare flanges. Good Luck
I agree -- that would be a huge helper . . . my only problem is that I'm running the huge D-Port Donovan fuel heads. They were designed for the 417 and are nothing like the stock 392 on either port side. The D-Ports are m***ive - so I need to make special flanges and fabricate the tubing ends. Once I get a couple inches away from the flanges, then it won't be any different than any other set of headers. I know that smaller diameter primary tubes would give me the best low-end torque/power, but with a blower and the type of car I"m building (60's style) - almost like a g***er), I think having 2" primary tubes will be much better looking. The real problem is figuring out if I can snake 4 equal length tubes down to a collector on a 34 ch***es --- I'm going to try, but who knows how this will turn out! Thanks for all the support and help. Dale
I have a totally *****en set of B***ett chrome zoomies for the 417 heads -- I'm going to use them to start the motor on the test stand. (Should make the neighbors happy . . . keeps the wax buildup out of their ears!). I don't know if you're ever seen B***ett's boat zoomies . . . about the best out there. (Wish I could TIG weld like they do!) When I start this beast - I'll take a couple pictures for fun and sharing.
The Jalopy Journal
