TIG used SS diesel exhaust?

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Hey, guys,I'm thinking of taking out a catalytic converter and possibly the muffler from a F-250 with 7.3 diesel to get exhaust temperatures down. Thinking of cutting out CC and muffler and welding in a new piece of SS tube in their place.I have a TIG but no mig and I don't know how to MIG very well anyway.Can this used stainless steel from a diesel exhaust be successfully tigged? Just grind/sand/clean/degrease it good?Also, it's inline and I want to do it on the truck, so I can't purge with argon. Can I use Solar Flux on the inside of the pipe and leave it there afterwards? Anyone tried anything like this? Disaster in the making?Thanks.Edit: Maybe I can argon purge at least one of the joints, on the piece I cut off the end. Not sure how I'd purge the second joint, closer to the engine...could I jam a piece of cardboard in there, and then let the diesel blow it out afterwards, since there will be no muffler or CC in the way to the tailpipe?Also, what filler? I have 308, 316L, 310 and maybe some 312...Last edited by Kelvin; 03-24-2016 at 10:32 AM.
Reply:If u have the skills u should be fine.   Clean and then solar flux. Make sure to tack every inch or soDynasty 200DX   (2014)Millermatic 211 (2015)Optrel 864   (2014)Smith Medium duty MBA 30510 (Xmas 2014)Tennsmith 16ga 4ft finger brake (2015)Trailblazer 325 EFI and excel Thermal dynamics Cutmaster 82Miller maxtron 450
Reply:Thanks. Will it rust afterwards in the weld/HAZ? I've heard heat makes some stainless steels rust.What kind of SS do they normally use to make exhausts? This is on a factory 2001 F-250 OEM exhaust.
Reply:409 is the most common for exhaust. With the 7.3 I'd look at the factory down pipe, they are squished down pretty good and a major flow restriction.
Reply:I'm sure any of those filler metals will work. I know 321 filler is for very high heat.  Have you welded ss?
Reply:The filler rod doesn't really matter on an exhaust, just use one that is stainless.All I have ever seen at all of the welding stores I have ever been to is 308 and 316.409 stainless is very common in vehicle exhaust.If its magnetic its a 400 series, if its non magnetic then its likely 304.For a diesel exhaust after the turbo what I would do is take a q-tip and solar flux the inside of the pipe ends, being very carful not to get any solar flux on the butting edges of the pipe.Don't use solar flux before the turbo.If you have a 7.3 in one of the older square body trucks there is a section of down pipe that is squished down to what looks like 1 to 1.5 inches wide to fit between the body and frame, be sure to replace that with something that is not so poorly designed.old Miller spectrum 625 Lincoln SP-135 T, CO2+0.025 wireMiller model 250 and WP-18V torchCraftsman 100amp AC/DC and WP-17V torchCentury 115-004 HF arc stabilizerHome made 4 transformer spot welderHome made alternator welder
Reply:YOU BETTER check with the local inspection station before you touch anything..Missing converters 99% of the time = FAIL at inspection time.The feds frown on such activities...And they WILL look!...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Thanks guys.What's inspection? Is that when they look out the window of the gas station and say, "Yep, looks like a truck to me ... that'll be $16. What's your mileage?"
Reply:Why don't you just use stainless steel band clamps?http://www.summitracing.com/parts/vp...FQZkhgodJisMNQRich
Reply:Originally Posted by steelsurgeonWhy don't you just use stainless steel band clamps?http://www.summitracing.com/parts/vp...FQZkhgodJisMNQ
Reply:If you want it to be easily removable you could look into V-bands, you weld one half of the coupler to each side of the joint and a special band clamp pulls them together.
Reply:Thanks, ironmangq, I didn't know about those, either.
Reply:I would definitely just grab some good band clamps, they are awesome and they seal great
Reply:Originally Posted by KelvinThanks, Rich, I did not know about those. So you can just butt-joint a couple pieces of exhaust pipe and join them that way? Pretty slick. That might be the way to go if I get into trouble.
Reply:I'd buy this for 220 bucks and be done with it. http://www.ebay.com/itm/4-Turbo-Back...250+Super+Duty
Reply:Originally Posted by steelsurgeonThey are supposed to be used by having one piece of tube slide into another piece of tube...like you would use a muffler clamp on. They are not recommended for butt joint connections.You buy them specifically for the size exhaust pipe you're using. They work great, and can easily be removed, if you decide to change something in the future.
Reply:Originally Posted by KelvinOK, that makes a lot more sense. Thanks.Huh, that doesn't look like a bad price. If I was going to go new, not sure whether I'd use aluminized steel, stainless 304 or stainless 4XX ... but thanks.