Ducman82

so im going to add some V-bands to my MSDS headers, and a magna flow muffler this week or next week.

i got a good deal on some 409 stainless, but decided to do it right and get 304.

i am trying to find 304 locally but i am not having to much luck.... i know you can use a magnet to test 409 as it sticks to it, and not to 304....

here is my question.

a local race shop has a 7' stick of 3" stainless that they will sell me for 50 bucks, used. it has a nice surface rust on it, and some pitting, "left out side for a while" BUT no magnet sticks to it......... 304 should not rust at all right?

the 409 U bent i got (to cut up) has the mag stick to it, the stright piece i got was ordered at 409, but no mag sticks to it...... UGH

any help on this magnet clarification would be great....

here is a pic of the pipe in question

123quattro

You should be able to have this at your door tomorrow with ground UPS shipping. This was the only 304SS pipe I found that Summit sells.

http://www.summitracing.com/parts/pte-h7717/overview/

I wouldn't be against 409. It's not as durable as 304, but is still really good. It will probably out last your car.

Wisconsin Joe

All stainless will rust under the right circumstances. Some just doesn't rust as easily or as badly.

jpitman2

And its much more brittle than mild steel, and likely to crack if not properly supported.
jp 83 Euro S AT 55k

tveltman

Also stainless can become slightly magnetic when worked, so depending on the extent of fabrication, the magnet test may not be foolproof (although something being nonmagnetic suggests that it is stainless). The only other thing that they would make the pipe out of would be aluminum, and you should be able to tell the difference by inspection (weight). More exotic options include monel 400 (if so, buy it, it would be worth a ton) or titanium, but the titanium absolutely should not rust.

Actually, are you sure that it is actually the tube rusting and not surface deposits of something like rusty rainwater?

Also, as said before, 304 will rust under certain circumstances. I routinely see (in my chemistry lab) 304 rusting, but we deal with corrosive things. Is it possible they left it near some sort of chemical waste? 316 is a more corrosion-resistant steel, but even in will rust if abused.

Ducman82

It was left in a pile with other muffler junk. So I could see rust from other things on it. It cleaned up with a scotch pad, but took some elbow grease. 100 bucks for 5' new. Or 50 for that 7' piece that requires some serious elbow grease... Ugh

U-928

All the stainless I've ever used from any and all of my exhaust work has come from mandrel-bends.com they also have a b-stock list if you don't need the bends to be perfect. Highly recommend these guys.

*they sell straight 304 for $10.50/foot*

Ducman82

I have worked with them before, cheap per foot, but shipping is Insane

Tim968

Hi Ducman, agree that "shipping" charges (more realistically 'markup' charges) make my Tourette's flare up as well...Hope it goes well with your 304 project. Agree with your scotchbrite elbow grease 'thang; Discipline with all buffing/grinding tools will mitigate rust "bloom" on 304/L. In many pipe-fab shops, craftsmen are required to keep all tools used for stainless separated from carbon steel tools, to mitigate rust bloom on stainless. This ends up as two fab areas each with separate tool cribs. I have toured shops where fitter/welders were literally subject to fines if they took tools across "the line". Best, T

Ducman82

ya, i have to sets of grinding tools/tig stuff for mild and one for stainless. thanks for the tips guys!