welding a flange to tubing

[Cinpro]

I need to weld a flange to exhaust tubing for a wastegate on a turbo set up. my concern is the flange is pretty thick compared to the tubing. i still mneed to get my tubing but the flange is 3/8 thick mild steel, the tubing will be most likely 16 or 18ga galvanized. there is a relief cut in the flange to insert the tube, do I need to try and weld this on the inside and out, then grind the inside smooth. its final location will be just off the exhaust manifold, only thing separating the two will be the wastegate, so it's going to get a lot of heat in its life.

my welder is a Hobart 140, 110v with an Argon mix.

am I going to be over my head with this and need to take it to someone? I'm a newbie on the welding scene but I'm mechanically handy guy, so I learn pretty quick. I hope I put enough info in here to get some help on this, if not tell me what you need to know.




.

[aametalmaster]

I would think the 110v welder would be a little light for this esp being 3/8 thick...Bob

[davedarragh]

I need to weld a flange to exhaust tubing for a wastegate on a turbo set up. my concern is the flange is pretty thick compared to the tubing. i still mneed to get my tubing but the flange is 3/8 thick mild steel, the tubing will be most likely 16 or 18ga galvanized. there is a relief cut in the flange to insert the tube, do I need to try and weld this on the inside and out, then grind the inside smooth. its final location will be just off the exhaust manifold, only thing separating the two will be the wastegate, so it's going to get a lot of heat in its life.

my welder is a Hobart 140, 110v with an Argon mix.

am I going to be over my head with this and need to take it to someone? I'm a newbie on the welding scene but I'm mechanically handy guy, so I learn pretty quick. I hope I put enough info in here to get some help on this, if not tell me what you need to know.




.

Is this for a gas or diesel? EGT's are around 900F for gas and 500F for diesel's at the turbo.

Here's what you should use: Low carbon Ferritic SS for the flange and pipe.

409L------------11% Cr or
410L------------12% Cr for the pipe

430LX-----------18% Cr-Nb for the flange

These should be welded with EC409 Stainless Steel, Gas-Shielded, Metal Cored MIG wire, which is specifically designed for welding "409" stainless used on exhaust systems.

Dave

[On fire most of the time]

As much as knowing what kind of fuel would help...what is your goal with the car, and what style car is it?

A 3/8" waste gate flange seems a little beefy for having some 16ga tubing attached to it. Personally, I think the best way to tackle this would be to go ahead and chamfer the inside of your flange on the tubing side, maybe an 1/8" and then fill the gap, aiming a touch more at the flange than at the tubing. If you burn in at all on that 3/8ths, and get full penetration on the 16ga, I should think it would have trouble going anywhere.

If from there you go ahead and weld the tubing to the inside of the flange on the waste gate end, and grind it down, there should be no issue. Yeah, it will probably eventually rust (if its all mild steel...Personally I would NOT use galvanized for this)

I dont know what the project is going on...but if it were me, I would probably use 14ga...since it is going to be on a turbo car, holding the wastegate (which is probably a few pounds) with some possible high EGT's.

But thats me.

[Cinpro]

this is going to be gasoline, 2.2l GM Ecotec engine, forged pistons, H-beam rods, 80lb injectors, turbo is a Precision 6157 t3/t4 with a 63 AR, oil cooled, intercooler, and a whole host of other bits an pieces. the goal is going to be 350-400ish crank hp.

A 3/8" waste gate flange seems a little beefy for having some 16ga tubing attached to it. Personally, I think the best way to tackle this would be to go ahead and chamfer the inside of your flange on the tubing side, maybe an 1/8" and then fill the gap, aiming a touch more at the flange than at the tubing. If you burn in at all on that 3/8ths, and get full penetration on the 16ga, I should think it would have trouble going anywhere.

If from there you go ahead and weld the tubing to the inside of the flange on the waste gate end, and grind it down, there should be no issue. Yeah, it will probably eventually rust (if its all mild steel...Personally I would NOT use galvanized for this)

there is a mounting flange on the turbos manifold already to hold the WG, this is for the outlet which will recirculate to the down pipe.( I knew I was leaving something out). and the flange does have a groove cut in it to insert the tube. I'll def look for some mild steel tubing to use. I'm thinking to do a small piece into the flange and then add my bends from there.

the EGTs get up there around +1100F, I'll be adding Meth injection to help with that.



.

[davedarragh]

this is going to be gasoline, 2.2l GM Ecotec engine, forged pistons, H-beam rods, 80lb injectors, turbo is a Precision 6157 t3/t4 with a 63 AR, oil cooled, intercooler, and a whole host of other bits an pieces. the goal is going to be 350-400ish crank hp.



there is a mounting flange on the turbos manifold already to hold the WG, this is for the outlet which will recirculate to the down pipe.( I knew I was leaving something out). and the flange does have a groove cut in it to insert the tube. I'll def look for some mild steel tubing to use. I'm thinking to do a small piece into the flange and then add my bends from there.

the EGTs get up there around +1100F, I'll be adding Meth injection to help with that



.

409 stainless will last for the life of this project, mild steel will corrode.

Dave

[TRFguy]

Well, this one is right up my alley. First off, A turbo'd gas engine will run over 1,600f if you're pushing it hard. Interestingly enough though, I was at Milan Dragway a few weeks ago, and got to talking turbo's with a GM test engineer. Per this gentleman, the ECOtech can handle over 2,000f. GM wanted to be able to run that motor LEAN for better mileage. Before anyone flames me for this one, I'm simply repeating what I was told. Although, the guy seemed very knowledgeable, and claimed to have been part of destructive testing to evaluate the limits of tolerable combustion temperatures. Take that for what you will.
Back to the point: I agree, a 110v MIG might be a little undersized, however, with some preheat especially, you can probably make it work. I'd heat up that flange a bit and then give it a go. You probably will be disapointed with galvanized tubing, it's not going to last, and welding it sucks, the fumes are nasty.
One last tip: If you do try this with your MIG machine, knowing it's a bit undersized, I'd strongly consider adding a support bracket somewhere to help support that wastegate, and thus make your welds do a lot less work.
Hope that helps,

[Cinpro]

that guy is right, the factory tune has you running right on the ragged edge of lean, with a wideband O2 I was seeing A/F in the 15.5 range most of the time with dips at idle that when as high as mid 17s, ouch. with tuning and recalibration with the motor N/A I now see nice mid 14s and when it goes into PE mode 12.5-13, the car pulls much stronger now.

back on topic:
I have been talking to several people who have also done their own turbo set up for this motor. most have been using aluminized steel bends like you would pick up from Summit or Jegs. they are good to 800C or nearly 1500F, since this is a first attempt I may go this route first for the practice in doing all the cutting etc that needs to be done and work on SS over the winter as a project. the wastegate inlet flange is SS and so is the turbos manifold, all fabricated by someone else. so there is plenty of support for it and the outlet is going to be welded to the downpipe so that will give it some extra support there. I was already considering doing a small bar on the side of the down pipe/wastegate pipe to take stress of on the weld that goes to the downpipe.

[SundownIII]

cinpro,

Personally, I wouldn't even consider doing this job with a 140A mig.

The material difference between the two pieces is too great.

If you don't have a tig welder available, I'd find someone who does.

Using tig, you're able to more precisely direct the heat. In this case most of the heat needs to be directed at the flange and not the tube itself. Once the puddle is established in the flange, filler can be added and washed over to the tubing.

Mig is just much harder to control. If you're hot enough to get penetration on the flange, you take the chance of burning thru the tubing.

[4sfed]

I need to weld a flange to exhaust tubing for a wastegate on a turbo set up. my concern is the flange is pretty thick compared to the tubing. i still mneed to get my tubing but the flange is 3/8 thick mild steel, the tubing will be most likely 16 or 18ga galvanized. there is a relief cut in the flange to insert the tube, do I need to try and weld this on the inside and out, then grind the inside smooth.

The best way to do this is to start with a thicker flange and machine it like this drawing. You are then welding two pieces of the same thickness . . . plus a butt joint is stronger than a fillet.

flange.jpg