Straightening the stainless weld job

Gentlemen,

I am a novice TIG welder on my fifth Argon bottle (small one) After what I thought to be a reasonable amount of practice and lot of excellent advice from this group I embarked on my first major project. This is going to be an turbo exhaust manifold. Although I still feel much like a novice I think that I was somewhat successful putting this together.

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Other than finishing touches, it is done but it has one flaw that needs to be corrected. The flange is somewhat warped. I fully expected this to happen and had it bolted to a jig and even welded temporary braces to it to minimize the warp. How to correct the flange warp? The turbo flange will be machined flat but I am afraid that the head flange will loose to much material if I have it machined. Could it be possible to bolt the flange to a chunk of high temperature material and heat the whole thing in a kiln? Will it be forced flat or flatter? I can force it into flat by bolting it to the engine head but I feel uneasy about all the unrelieved stress. Than again then the turbo spools up these things glow cherry red.

My wife has pottery kiln that can go over 2100°F

The flange and tubing is 304L The tubing is schedule 40. I know that there are better and more expensive alloys for doing this. This is a learning compromise. Any suggestions would be most welcome.

Regards,

Boris Mohar

Got Knock? - see: Viatrack Printed Circuit Designs (among other things)

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Reply to
Boris Mohar
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Boris

Well the bending is in there now, but it is in the easier to fix direction

Method A. Apply lots of heat quickly to outside of head flange with oxy acetylene and when you get a bit of glowing colour, quench with wet sponge or towling. The contraction on cooling will be greater than the expansion when heated and the flange plate will bend, lots of small attempts are the best approach with this method. and will definately be trial and error. Work small points down the length. Check with a straight edge. The goal here is just to get is close. You are not attempting to get the whole thing perfect, just close so that less material needs to be machined away.

Method B. Another option is to well support the plate either side of two of the pipes and with a large rubber bend the connecting section of the head flange between these pipes. Work a little bit at each of the three points. Check with a straight edge. The goal here is just to get is close. You are not attempting to get the whole thing perfect, just close so that less material needs to be machined away.

Then get the machining done. Welding is about 10 percent of the job you set yourself here.

Geoffrey Rowe

Reply to
Grant Lee

Your original strongback should have been much heavier and a few little tack welds along with bolting would have helped. Afterward you could have unbolted and notched the tacks with a small grinder to separate. I would have used something like a four inch square three eighths wall tube. If you can find at least a three inch square quarter wall you might try bolting the flange to it. Drill and tap your holes in the tubing. Bolt your manifold down. Heat to red quickly around the flange to pipe connections. Let cool to black before quenching. Several cycles of tightening the bolts until you get proper seating would likely do the trick. Please note that hot soaking stainless is not good for the corrosion resistant properties. Some of the warping will be caused by the pull of the pipes way back from the joints to the flange. Hopefully you don't have to heat the pipes too far back. Randy

Gentlemen,

I am a novice TIG welder on my fifth Argon bottle (small one) After what I thought to be a reasonable amount of practice and lot of excellent advice from this group I embarked on my first major project. This is going to be an turbo exhaust manifold. Although I still feel much like a novice I think that I was somewhat successful putting this together.

formatting link
Other than finishing touches, it is done but it has one flaw that needs to be corrected. The flange is somewhat warped. I fully expected this to happen and had it bolted to a jig and even welded temporary braces to it to minimize the warp. How to correct the flange warp? The turbo flange will be machined flat but I am afraid that the head flange will loose to much material if I have it machined. Could it be possible to bolt the flange to a chunk of high temperature material and heat the whole thing in a kiln? Will it be forced flat or flatter? I can force it into flat by bolting it to the engine head but I feel uneasy about all the unrelieved stress. Than again then the turbo spools up these things glow cherry red.

My wife has pottery kiln that can go over 2100°F

The flange and tubing is 304L The tubing is schedule 40. I know that there are better and more expensive alloys for doing this. This is a learning compromise. Any suggestions would be most welcome.

Regards,

Boris Mohar

Got Knock? - see: Viatrack Printed Circuit Designs (among other things)

formatting link
void _-void-_ in the obvious place

Reply to
R. Zimmerman

Looks pretty frigging good for an amateur job! I build sheetmetal intakes and exhaust for drag racing and I'm on page with your warpage.. Here is what I do. The flange- bolt it to 3/8" thick copper under 1/2" plate steel with button head cap screws so you can weld around the flange without fighting bolt heads. Works like a charm also, where the plenum mounts, I make mine a bit thick so if I have an issue I can mill it true and then the problem is gone. The copper plate pulls so much of the heat off I have never had an issue since switching to that method. And I have built some wild blower manifolds I was sure were going to warp being very thick stock- not a problem. Also a wet rag stuffed in the turbo flange or heat putty works too. Your work looks really good to me. Your doing GREAT if this is just a start at making this stuff.. Struggling with the joints is a bitch and always will be but your work looks clean in the joint areas. You will have a lot better time with a more appropriate metal too. but your off to a great start for sure!!

Rob Fraser

Fraser Competition Engines Chicago, IL. Long Beach, CA.

Reply to
RDF

I am not sure I understand this. I understand the part about the copper steel sandwich but the manifold is done. What is there to weld?

Regards,

Boris Mohar

Got Knock? - see: Viatrack Printed Circuit Designs (among other things)

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void _-void-_ in the obvious place

Reply to
Boris Mohar

Can I put a thermal barrier in between the flange and the three inch square quarter to minimize the heat gradient and loss?

Would peening the joints with a ball peen hammer cause them to expand?

This is unavoidable. The turbo exhaust manifold will glow cherry red under full boost. It will be coated to keep out the gasses and to minimize the heat loss.

--

Boris Mohar

Reply to
Boris Mohar

Boris, This is for the next time you make one, it eliminates the warpage.

Rob

Reply to
RDF

Peening is intended to relieve stresses or to stretch things. It would be difficult to apply a hammer to the right spot. If you just heat the manifold again while it is forced tight to something rigid it will conform. If the whole thing is red hot while operating I would go crazy with the heat using a rose bud torch. Here I was worried about your stainless. I keep thinking dairy equipment or kitchen ware :'))) I would not bother isolating the strongback tube. In fact I would preheat it a bit to say 300 F . If the flange surface of the tube was heated only then the tube actually will take a noticeable bow over a two foot length. I am not talking about red heat. 300 degrees on one side full length will bow the tube until the heat evens out on it. The 300 will mimic the temp of your engine block surface. I don't like quenching something like this. Just let it cool in air. I quench stuff for two reasons when heat shrinking. One is to save time and see if I have shrunk the weldment enough and the other is to increase the gradient between the red area I am shrinking and the surrounding metal. In your case you are not really shrinking metal. You are primarily stress relieving. Randy

Can I put a thermal barrier in between the flange and the three inch square quarter to minimize the heat gradient and loss?

Would peening the joints with a ball peen hammer cause them to expand?

This is unavoidable. The turbo exhaust manifold will glow cherry red under full boost. It will be coated to keep out the gasses and to minimize the heat loss.

--

Boris Mohar

Reply to
R. Zimmerman

Are you using Al or SS for the intakes? Lately I've been on a steel over Al kick for intakes lately (but then again I'm a boost/nitrous guy)

Reply to
cl

This is an SS turbo exhaust manifold. When this project is finished I will be learning how to weld Al and pleading for help here.

Regards,

Boris Mohar

Got Knock? - see: Viatrack Printed Circuit Designs (among other things)

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void _-void-_ in the obvious place

Reply to
Boris Mohar

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