welding stainless steel exhaust

[frankv11]

working on finishing up 3" stainless steel exhaust. its is tack welded with a mig ( passport plus ) using .035 308 wire and stain mix gas. been practicing on scrap pieces but it seems like i'm going to need to get it tig welded,


so my question has anyone accomplished a good looking weld with mig and if so please share ,settings, process ,pics:D. I will be grinding down weld for esthetics but trying to minimize as much as possible. I'm sure I will need to purge if I decide to tackle this if its possible. .



stain mix has a lot splatter should I be using cO2 or other shielding gas.

[Vince@Meanstreets]

http://www.pro-touring.com/showthread.php?92168-The-art-of-purge-welding(-back-purging)

heres a great thread regarding stainless exhaust. I run a separate tank and regulator to purge it. Temps are 29-38 on my Miller 180 SD tig.

Its all in the prep. Get your joints nice and tight. I get lazy sometimes on fitment but I can get by. For me its easier to TIG weld exhaust thank MIG. Slower but easier.

Practice-Practice-Practice

[Vince@Meanstreets]

your vid..



JohBHzhOyPg

[GregWeld]

I WOULD NOT grind down welds on the SS exhaust.... they'll tend to crack. SS expands and contracts more than mild steel.

The SS exhaust on my roadster has a hairline crack at almost every weld (butt welded) joint.. it was ground down and mirror polished. I will have to re-do the entire system.

Talking with Roy Brizio about this -- he said they no longer use SS for exhaust and if they do they NEVER grind the welds.

[GregWeld]

Frank --

You don't mention if you're building a SEMA quality show car or a driver hot rod etc... if you're building a show car - I'd ONLY TIG weld. There's no way you're going to MIG it and have it look show quality. But if you're building a PT style driver that you're going to hammer... then MIG would be fine.

It really just makes a difference in what you're building.

[frankv11]

Vince thanks for info !
Greg that's one of the reasons I really would like to grind as least as possible while Have it looking good. It's going to be a daily driver / show car/ autocrosser, did not start out that way but that's where it's going now.

I'm hoping to get a descent mig weld but yes tig is the way to go. Worst case I'll see if I can find some one local to finish if.

Hairline cracks that's got to suck!!!

[GregWeld]

Hairline cracks that's got to suck!!!



Yes they do! And given the cost of a full custom built - food grade stainless - polished - headers to the tip system... I'm not happy about it!

But I'll just take the whole system off this winter and blast the insides and re-weld it and then polish the welds. It's like everything else on that little POS -- I've had to re do the entire car...

[Cris@JCG]

here is what SS exhaust looked like after running it @ RTTC this weekend on Blu Balz... I had to drive the car back from Irvine to LAX to drop off Karl @ the airport then drive to Oxnard.. I was deaf when I got home!

Notice that it did not break @ the welds.. I think my exhaust system is a little to stiff.. need some more rubber exhaust hangers..

http://i1015.photobucket.com/albums/af278/jcgrestoration/IMG_2747.jpg

http://i1015.photobucket.com/albums/af278/jcgrestoration/IMG_2746.jpg

[Sieg]

Interesting cross-over, tough to factor all the stress points with expansion/contraction and I'll assume torque twist.
Looks like some of the beads could have caused stress-risers?
Some broke behind the bead, material became brittle after welding?

[badmatt]

Looks like stress fracture. starts from no where.

Drill a hole in each end, weld it, then lap some new .065" stainless sheet over it.

Just a thought.

[GregWeld]

Mine is not cracked like that -- mine is tiny HAIRLINE cracks that just follow the part line (weld line) where the tubing was butted. It annoys me only in the fact that this exhaust system was several grand... :unibrow:

They hard mounted the system - and that was their first mistake - and I think it was that initial expansion and contraction with it being hard mounted that set up the hairline cracks... It's since been re hung allowing for some movement.

My system "grows" at least ONE INCH in length... And Tim came up with a masterful redesign of the hanger to accommodate that.

[badmatt]

Mine is not cracked like that -- mine is tiny HAIRLINE cracks that just follow the part line (weld line) where the tubing was butted. It annoys me only in the fact that this exhaust system was several grand... :unibrow:

They hard mounted the system - and that was their first mistake - and I think it was that initial expansion and contraction with it being hard mounted that set up the hairline cracks... It's since been re hung allowing for some movement.

My system "grows" at least ONE INCH in length... And Tim came up with a masterful redesign of the hanger to accommodate that.


Hmm surprised they didnt do a fusion "root" pass then a cap..

/weld inspection theory.

[GregWeld]

Hmm surprised they didnt do a fusion "root" pass then a cap..

/weld inspection theory.



I guess a root and cap -- on tubing that's .060 or .080 wall ... and then grind it off and mirror polish?

I want to see what your cars look like -- you must have some AWESOME stuff!! :D

[badmatt]

I guess a root and cap -- on tubing that's .060 or .080 wall ... and then grind it off and mirror polish?

I want to see what your cars look like -- you must have some AWESOME stuff!! :D

My stuff is all junk haha.

[frankv11]

My system "grows" at least ONE INCH in length... And Tim came up with a masterful redesign of the hanger to accommodate that.[/QUOTE]

Hard mount cross my mind but I also noticed on my truck that it reall grows quite a bit so I'm going to be running flex line at headers and at tips . its going to be hung real close go body with high temp grommets. Hopefully that will help a bit.
See you @ sema

[Vince@Meanstreets]

Im a big fan of those SS flex sections that RS and Marquez Design use. Look to those ring and rod style hangars. Seem to work well for the OEM's.

[GriffithMetal]

Hmm surprised they didnt do a fusion "root" pass then a cap..

/weld inspection theory.

Stainless shrinks a bunch when you weld it. If you pass multiple welds on the same seam the area will be lower. If you are trying to remove the weld and polish then there will be low areas where you welded. IMHO smoothed out stainless exhaust is for show cars that won't be driven much. It's expensive to build and has poor longevity. Leave the welds on stainless exhaust if you plan on driving it. Be sure to back purge the tubing or use a weld flux to prevent sugaring.

[Revved]

I've started integrating flex couplers whenever possible into my exhaust systems. Just like an OE system... anyway you can eliminate vibrations the better. Vibrant Performance makes serveral sizes and styles.

http://vibrantperformance.com/catalog/index.php?cPath=1022_1064

[E.rodz]

a few thoughts for you one of the trucks that I built was done completely in stainless and I will not do that again for the same reason as Greg has stated I tig welded the whole thing and stainless warps badly from the heat way way worse . I tacked the whole system and then starting welding 1 inch random welds at a time it pulled so bad in every direction I had to cut many of the welds apart ad do the over again to make things line up where they were to go though hangers and such. the crossover pipe cracked in no time and that bright shiny look lasted about a week the it turns gold colored. if you bring it to some one to redo it in tig it will pull all over the place and the guy you bring it to will hate you for have to try to make it look good if he has to grind down all the welds. the more it is welded the more brittle it will become. don't weld it solid just tack it with the wire then tig it with a purge to prevent sugaring.tri mix gas is what you should be using for the mig. don't mean to disappoint just trying to help.

[frankv11]

Thanks to all for the Info.
My original intentions were to get a good solid weld with mig preferably (because I have no tig) but it seems more like I will need to get it tigged to get what I'm looking for. I'm not going to gring the welds down or polished it.

Now if I could weld it with mig and not get Sugar on the inside. I will gring just a tad ( no where near flush )

[GregWeld]

Stainless shrinks a bunch when you weld it. If you pass multiple welds on the same seam the area will be lower. If you are trying to remove the weld and polish then there will be low areas where you welded. IMHO smoothed out stainless exhaust is for show cars that won't be driven much. It's expensive to build and has poor longevity. Leave the welds on stainless exhaust if you plan on driving it. Be sure to back purge the tubing or use a weld flux to prevent sugaring.


I will second this 100%... as the food grade SS exhaust on my Steve Frisbee built '32 Ford... has had to be repaired now for the second time. They (SAR) flushed the welds and polished the entire system... I drive the crap out of my stuff... and the system has/had hairline cracks at every seam. The SS also GROWS a BUNCH... and this has caused other issues.

I will nurse this thru this summer and then the car goes to Brizio for an all new exhaust system. :thumbsup: You know - one that actually works.:D

[E.rodz]

try triggering the weld just doing one tack after another not doing it solid turn your heat down and purge it with any inert gas it will work just practice a bit more it is possible just not the best way but it does work. good luck with any way you choose.myself would use mild steel and send it out to get it ceramic coated after looks better and stays that way.:D

[Sieg]

myself would use mild steel and send it out to get it ceramic coated after looks better and stays that way.:D
All said and done I agree. Stainless has too many drawbacks for my application.

[GregWeld]

I agree... even Brizio said they stopped doing stainless exhaust systems...



If you're going to do SS exhaust -- use 321 stainless from a supplier like Burns Stainless.

[dontlifttoshift]

I guess I am the odd man out. I like stainless exhaust. If built properly it will last the life of the car, it is easier to maintain than a coated exhaust, and actually does a better job of retaining heat than mild steel.

[GregWeld]

Like most things Donny -- you've got to use the correct materials for the job.

[J2SpeedandCustom]

Most failures on stainless exhaust come from improper mounting of the exhaust. Since the stainless grows then shrinks a ton using multiple expansion couplers, and making sure the rest of the mounts can move on the car is paramount.

I always laugh when I tell a customer that his side exhaust tip is going to stick out up to an 1" from where it is cold, and that it will return. The response is "really I've never seen that before, my buddies doesn't do that." LOL Well then your "buddies" isn't stainless...

[67zo6Camaro]

Im wondering if the wrong grade stainless was used. It seams that most over-the counter stainless is the 304 grade.

Anybody use the 321, 347 or the specific 409 grade for exhaust.

I was just looking at the stainless grade chart and the 321,347 is a stabilised grade for heavy section welding and high temperatures.

Then I saw that the stainless grade 409 is listed as automotive exhaust grade that is weld stabilised.

I was thinking of building a light weight stainless exhaust similar to an airplane, but now I maybe second quesing that idea based on what Im seeing here.

[GregWeld]

409 is NOT for nice cars exhaust systems.... as it forms a light layer of rust. That's not the kind of stainless exhaust "we" are looking for.

321 does NOT polish well.... but otherwise works well for our purposes. I'll add that it is better for higher heat applications than normal 304

The food grade stainless in my '32 exhaust is polished to a mirror grade -- but the growth/shrinkage rate is really unacceptable in an exhaust system other
than a "show" car. The food grade tubing works great for bends - since the diameter matches up no matter where you cut it. In other words - you can buy a 90 or 180 and cut it and match it to another cut curved piece and the diameters match up. Nice in a show car exhaust system -- really not very critical in an under car
"used/abused" PT car.

[frankv11]

Most failures on stainless exhaust come from improper mounting of the exhaust. Since the stainless grows then shrinks a ton using multiple expansion couplers, and making sure the rest of the mounts can move on the car is paramount.

Very nicely put :thumbsup: I'm making mine all 304 SS ( headers to the tailpipe) don't want corrosion holes down the line among its other benefits.

That is my struggle, giving it room to expand while keeping it tight to the body.

[Deano9666]

IMO , stay away from the mig , tig only
When I weld stainless, I only use straight argon, tight gap, and purge
Remember stainless expands 4 times more than carbon steel , expansion in the way of long hangers
Good luck:thumbsup: :thumbsup: :thumbsup: :thumbsup:

[frankv11]

Got this on mind, 321 SS bellows w interior sleeve ( directional ) these will compress , stretch , handle vibration and heat so they can be used close to or at collector. Like everything else it has its limitations but I'm not sending this thing to the moon:D

A stainless steel single or multiply bellows designed to accommodate pipe growth due to thermal conditions in engine exhaust piping. Series EFB bellows are also constructed to absorb vibration normally associated with engines and generators. Bellows are series 300 stainless steel and can incorporate internal flow liners where necessary. The light weight bellows is highly flexible and will protect the low pressure exhaust piping. End connections can be standard commercial 150# ANSI drilling, beveled weld ends, or special flange styles such as Caterpillar, Cummins, or Detroit Diesel. Exhaust bellows expansion joints are made to order, according to the pipe motion expected, temperature, velocity, vibration, and end connections.

[Deano9666]

Not to jump on your thread but ....
That's actually a awesome idea, I was thinkin the same thing.
Well actually I was talkin with a union brother and we came up with it together, we use these in the oil and gas industry coming of headers, usually 18+ " in diameter , these expansion bellows.
But your suggestion , who would supply those, you have a contact with 300 series stainless in a 3 " scenario

[frankv11]

Not to jump on your thread but ....
That's actually a awesome idea, I was thinkin the same thing.
Well actually I was talkin with a union brother and we came up with it together, we use these in the oil and gas industry coming of headers, usually 18+ " in diameter , these expansion bellows.
But your suggestion , who would supply those, you have a contact with 300 series stainless in a 3 " scenario

Yeah I found some 3" 321 SS With sleeve as mentioned. If interested let me get my hands on them and I'll post up results

[GregWeld]

Not to jump on your thread but ....
That's actually a awesome idea, I was thinkin the same thing.
Well actually I was talkin with a union brother and we came up with it together, we use these in the oil and gas industry coming of headers, usually 18+ " in diameter , these expansion bellows.
But your suggestion , who would supply those, you have a contact with 300 series stainless in a 3 " scenario



Just one source...there are many others.


http://www.stainlessworks.net/products/build-components/flex-joints.html

[Sieg]

Just one source...there are many others.


http://www.stainlessworks.net/products/build-components/flex-joints.html
This one had a good selection too:
http://vibrantperformance.com/catalog/index.php?cPath=1022

[frankv11]

flex joints are readily available just about anywhere but the bellows in mind ( picture below ) are just a bit harder to find locally. since they are normally about $100 a pop I want to get to see it before I buy.

I already have the flex joints in there but those well not stretch or compress as much they're more for vibration. these bellows are more durable and suitable for this application.
http://i1232.photobucket.com/albums/ff363/frankv11/photo.jpg

[frankv11]

some pictures of the progress
http://i1232.photobucket.com/albums/ff363/frankv11/photo2-16.jpg
http://i1232.photobucket.com/albums/ff363/frankv11/photo4-15.jpghttp://i1232.photobucket.com/albums/ff363/frankv11/photo5-7.jpg
these are the ones I'm looking to replace since they're right at the collector..

[GregWeld]

What you have will do the job as they also help with expansion and vibration issues....


Read the description on this "flex" joint and they say that the bellows style creates turbulence.... and I'd agree. Whether it's critical for your application is a different issue.


3" versions.

http://www.treadstoneperformance.com/product.phtml?p=2063&prodname=3+%22+Stainless+Steel+Exhaust+Flex+Couple r+Bellow


Vibrant does NOT carry flex bellows in 3"

[GregWeld]

These guys supply the BELLOWS style with an internal slip joint for smoothness....



http://www.spdexhaust.com/pdfs/AccPDFs/Bellows.pdf

[frankv11]

These guys supply the BELLOWS style with an internal slip joint for smoothness....



http://www.spdexhaust.com/pdfs/AccPDFs/Bellows.pdf

Those are exactly what I'm looking to buy, with interior sleeve / directional. I could be wrong but the ones that I'm replacing don't seem like they would be compression friendly. I need some that will compress when exhaust stretches out from its natural state to eliminate some of the stress , tension , binding.

I'm doing a bit of research on how much it will actually stretch. The only thing I'm missing is the over all running temperature of the exhaust system.

[GregWeld]

Those are exactly what I'm looking to buy, with interior sleeve / directional. I could be wrong but the ones that I'm replacing don't seem like they would be compression friendly. I need some that will compress when exhaust stretches out from its natural state to eliminate some of the stress , tension , binding.

I'm doing a bit of research on how much it will actually stretch. The only thing I'm missing is the over all running temperature of the exhaust system.

The exhaust on my short little '32 ford grows an inch!

[frankv11]

The exhaust on my short little '32 ford grows an inch!

mine is defenitly going to grow a lot more than one inch...LOL

[snappytravis]

I was recently thinking of stainless exhaust for my 69 camaro. After reading throught this thread I am having second thoughts, What about using regular steel exhaust then having powder coated?

[preston]

Yeah I'm surprised the brain trust here is down on Stainless exhaust. I built many custom steel exhausts and its expensive to coat and my experience with the local coater down there in Auburn hasn't been that great durability wise (scratches then rusts). I finally built a full SS exhaust for my rig and was so much happier with the appearance and performance. I constantly change things so I appreciate being able to cut apart the exhaust and re-weld it without having to get it recoated. I do have a flex joint and plenty of very flexible hangers. I must be the really odd man out because I build my turbo headers from steel and my exhaust from SS and haven't had a problem with either and the car has been tracked several times.

Anyway, my question is back to welding SS - I've read many times your welds/metal should be silver or gold colored or at least shiny when done and that gray is bad. Well most of my welds ended up gray - its been a while since I've welded SS so maybe it would work out better now but I'm having a hard time figuring out what I was doing wrong. I think the gray is too much heat ? But I work that pedal up and down and only use enough heat to do the job, obvioulsy if you use too much you blow through and not enough is easy enough to see. This was mostly on 3" exhaust without backpurging, but including many v-band flanges and such where there was no open air backside. TIG welding using .063 stick on .063 wall thickness runnnig pure Argon (or whatever the standard TIG mix is) and probably 65-75 amps at full throttle on my Lincoln square wave.

Any tips on what I'm doing wrong ?
BTW I've never had any SS weld crack although I never grind them down.

[dontlifttoshift]

My experience is too much heat makes it gray and chalky. 65 to 75 amps sounds about right but I very rarely hit wide open, I don't back purge exhaust either unless it is being polished. It's not just the amount of heat but how long you put the heat in. That's why fitup is so important, if you are trying to "bridge" a gap that requires some time and that can burn the color out of it. That's been my experience.

Here's a secret, I don't even use filler rod on the seams of unpolished exhaust. SShhh.....the welding nazis get mad when they hear that, but that's the way I do it and I have never had a problem.


Headers are another story, I always backpurge.......well not really. I use a local shop that welds sanitary stuff all day, everyday, they do it so cheap its not worth my time. Same with polished exhaust, I tack it and drop it off, and it comes back polished

[preston]

Thanks for the tips. My TIG welding has come a long ways since I last did SS so maybe it will come out better next time. I mostly do aluminum but lately I have been doing alot of bodywork and I have been having success fusion welding 20 awg steel which makes me absolutely giddy. So yeah I would probably do a better job on moving quicklythat was probably my issue, spending too much time in one spot. I have found you are better off leaving a bad bead or void in your wake in order to keep the heat moving and going back and melting/fixing rather than lingering and trying to fix it then.
Not sure I would trust fusion welded exhaust pipes though, need the extra strength there. On body patches not so much.

[dontlifttoshift]

Not sure I would trust fusion welded exhaust pipes though, need the extra strength there. On body patches not so much.

You got that backwards, ridiculously expensive paint jobs go on the body work.:)

You have built the exhaust so you know, Have you tacked one joint together and then had to take it apart? 4 good tacks and you have a hell of a time getting it apart.

A 3" tube has over 9" of weld holding it together at each seam. Again, fit up is key. A perfectly fitup joint will fusion weld with no problem. The sanitary guys have automatic welders as well. There are two styles, one that spins the pipe and one that spins the tungsten around the pipe, neither one uses filler of any kind.

Another thing that will make it gray and chalky is dirty tungsten or getting a contaminant in the weld.

[funcars]

Coeff of thermal expansions for those who like specs: - 304 11x10E-6 in/in/deg F, 321 11.4x10E-6, 316L 10.8x10E-6, low carbon steel 6.3x10E-6

[ccracin]

You also must remember that the tubing gets cooler the further back you go. It becomes a fun calculation! :headscratch:

[frankv11]

got some info
http://www.unisource-mfg.com/images/inventory/169/pdf/Exp_Joint_Basic_Info.pdf

[The WidowMaker]

fusion welded the 304 on my 70 but dont have a motor yet. did the same for my silverado and im at a year with no issues. i agree that a few tacks were murder to take apart. not so much for a mig since its more difficult to get the heat with a tack.

[64pontiac]

I haven't seem to have had the "growing" issues as much as some of you.....I am sure at some point I will have to deal with it though.

All of our stuff runs flex joints and the "snapper" grommets that were seen in the pics a bit back. But I mount them bolted to another bracket.

Also, I have put some serious heat into the exhaust via super and turbo charging, and I have yet to have my stainless stuff get grey like the pic of Blu Ballz exhaust.....I know he tracks it, but the crossover section there is a bit back from the collectors....ours only goes gold/purple. Is this just exterior contamination like oil that makes it go overheat grey like that? Maybe that has to do with the cracking.

I have use fusion on stainless exhaust joints too, it looks amazing. I havent been experiencing the sugaring issues that much, I have only purges on header tubes, not our exhaust systems.

What tungstens are you guys using? On 16 gauge stainless I am only running 30 amps max to get a nice bead. I have never had to put 60 amp into stainless exhaust unless I am adding an 1/8 inch thick bracket or muffler/flex joint lap welds. I guess its all in the welder operator!

Good info in here. I do believe you on the exhaust growing Greg, just haven't experienced it myself.

[GregWeld]

Good info in here. I do believe you on the exhaust growing Greg, just haven't experienced it myself.



My little '32 doesn't have any flex joints in it... and that's the problem with that particular system. If it did -- it would have been fine.


The "old trick" I've used to figure where the crossover goes -- spray some paint on the exhaust after the collector --- from there back about 18" ---- Run the system -- and put the crossover where the paint 'boiled'. But that was before the days of "X" pipes. And is probably about as scientific as spitting.

[jst8a5.0]

geez i have built a ton of ss systems and i have only had one turbo manifold crack but it was for a ton of reasons working against the manifold itself such as wheel hop, no flex coupler, the car bottomed out a few good times, heavy turbo was hung directly off the manifold with no support, etc....

[parsonsj]

Love this discussion!

Coeff of thermal expansions for those who like specs: - 304 11x10E-6 in/in/deg F, 321 11.4x10E-6, 316L 10.8x10E-6, low carbon steel 6.3x10E-6That's the data we need. SS grows a bit less than twice as much as mild steel, and a typical SS exhaust will grow about 0.3 to 0.4 inches, given 800 degree temps at the collector, 400 at the muffler, and 200 at the tail pipe. More heat: more growth, more length: more growth, etc.

I've been fusion-welding SS exhaust since I saw the Stainless Works welders doing it. I spend a lot of time on fit-up, de-burr all weld edges, and clean the metal with acetone before welding. I use 35-40 amps on 16g, and back-purge everything.

Because SS moves so much during welding, I fully weld the exhaust tubes as I go. Tacking the whole thing and then fully welding makes it difficult to keep everything where you want it. Plus you get to do some of the early welds without having 6 feet of tube rolling around while you weld.

[toddoky]

All of the issues discussed here is why I don't use 304 for building exhaust systems; it is an un-stabilized austenitic grade of stainless that is not recommended for use in high temperature applications (850 degree F. use temp threshold). If you need increased high-temperature strength beyond what mild steel provides, 321 and 347 are the stabilized grades that can provide it by design. 304 became the poor-mans stainless exhaust material due to its availability and affordable price (relative to 321 and 347) and the fact that its the only lower-cost option most people think they have besides using 409ss. If you want to use an affordable stainless material that is designed for use in a high-temp environment with better corrosion resistance than 304 in cyclic high-temp applications (i.e. exhaust systems) look at the stabilized 2nd-generation ferritic grade 439. It has the same 18 percent chromium content that 304 has (409 has 11.5 percent)without the nickel content, which is the real price driver of the austenitic grades. I've used it to build headers and exhaust systems for 15 years without any issues and highly recommend it. Its coefficient of thermal expansion is closer to mild steel than it is to 304. The trouble with using it is in finding it in U/J-bend form but you can find them in many different tube diameters from Bassani Manufacturing in Anaheim, Ca.

[Vince@Meanstreets]

All of the issues discussed here is why I don't use 304 for building exhaust systems; it is an un-stabilized austenitic grade of stainless that is not recommended for use in high temperature applications (850 degree F. use temp threshold). If you need increased high-temperature strength beyond what mild steel provides, 321 and 347 are the stabilized grades that can provide it by design. 304 became the poor-mans stainless exhaust material due to its availability and affordable price (relative to 321 and 347) and the fact that its the only lower-cost option most people think they have besides using 409ss. If you want to use an affordable stainless material that is designed for use in a high-temp environment with better corrosion resistance than 304 in cyclic high-temp applications (i.e. exhaust systems) look at the stabilized 2nd-generation ferritic grade 439. It has the same 18 percent chromium content that 304 has (409 has 11.5 percent)without the nickel content, which is the real price driver of the austenitic grades. I've used it to build headers and exhaust systems for 15 years without any issues and highly recommend it. Its coefficient of thermal expansion is closer to mild steel than it is to 304. The trouble with using it is in finding it in U/J-bend form but you can find them in many different tube diameters from Bassani Manufacturing in Anaheim, Ca.

and because average people don't know about alternatives...its become an industry standard.

What is the cost difference and what filler is used with it?

[toddoky]

and because average people don't know about alternatives...its become an industry standard.

What is the cost difference and what filler is used with it?


In terms of typical coil prices, it runs about 30-35% less than 304 on the market. When it comes to U-bend prices I haven't shopped 304 U-bends recently to be able to compare but was absolutely floored the last time I saw the prices for single 304 U-bends from the typical outlets...you'd think the stuff was made of gold instead of stainless steel. You could make an easy comparison by calling Bassani and asking for a price for a common U-bend size, such as 2-1/2 on a 4" radius and then shop prices for the same in 304 from the known suppliers of 304 U-bends (the list is too long to mention). Once you factor in the superior cyclic high temp corrosion properties of 439 and its much lower coefficient of thermal expansion, it's a no-brainer for me even if it was the same price as 304. The only place I wouldn't recommend it is when you need the increase in high temperature strength that the austenitic grades provide (i.e. hot side turbo plumbing on a competition vehicle), but in that case I would skip over 304 and go right to 321 or 347 as they are not subject to stress corrosion cracking like 304 is. 439 can be autogeneously welded (no filler rod) or be welded to itself with a matching 439 filler wire (if you can find it locally) or the common 308L austenitic filler wire. You can weld it to 304ss or low carbon steels by using 309L filler wire, which is the go-to stardard for dissimilar metal welds of this type.