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Posted by: toon1 Feb 25 2009, 01:07 PM

Does anyone know what grade or type of stainless the HE's are made of?

I'm going to do some welding on them for a muffler mod. and want to setup my welder.

Posted by: sean_v8_914 Feb 25 2009, 05:28 PM

call SSi and ask them. this is not a somple quetion because I think they changed amid production

Posted by: kwales Feb 25 2009, 07:00 PM

There's actually 2 kinds of stainless used in them...

rusty stainless and non rusty stainless.....

Rusty stainless is the pipes,

Non rusty is the sheet metal...

Guy I know who does metalurgy at GE aircraft engines told me, but that was at least 10 years ago and I forgot what grade.....

I think the non-rusty grade is 303 or 304...

The pipes?????

Ken

Posted by: SLITS Feb 25 2009, 07:15 PM

500 has the most iron and rusts like a teener and is magnetic

400 has less and rusts less and I don't remember if it has magnetic qualities (most catalytics shells are this material I think)

300 is the shiny shit that doesn't rust and is not magnetic.

Posted by: jd74914 Feb 25 2009, 08:14 PM

304 stainless is pretty rust resistant, but does rust, especially in certain water environments. I would bet that the pipes are made from 316 since I haven't seen any pictures of rusty heat exchanger bodies. That grade (and up) is very resistance to rusting, even in harsh deionized water environments.

More for curiosity sake, when you do find out could you let us know what the alloy is?

As far as future rust prevention is concerned, post-welding passivation is probably much more important than welding with the exactly correct alloy. If you do not passivate after welding it will rust.

Posted by: toon1 Feb 25 2009, 08:55 PM

What does "passivate " mean?

Posted by: SirAndy Feb 25 2009, 09:01 PM

http://www.mmsonline.com/articles/how-to-passivate-stainless-steel-parts.aspx

Posted by: rjames Feb 25 2009, 09:04 PM

What the hell did I do before google?


http://www.mmsonline.com/articles/how-to-passivate-stainless-steel-parts.aspx

Posted by: DBCooper Feb 26 2009, 06:01 AM

Don't want to seem picky, but this one hurt me. We had a customer put a magnet on a product and say "That ain't 302!" Problem is that it was. They're considered non-magnetic but a number of the 300 alloys are actually weakly magnetic, and weirdly enough get more so when they're cold-worked. Even more so when they come from China, probably. I didn't know that, got caught flat-footed, and stood there with my mouth open. And for good order's sake some will oxidize a bit, depending on grade and conditions. 316 is considered "marine grade", for example, while 302 and 304 are not for marine environments.

Posted by: jd74914 Feb 26 2009, 06:40 AM

Good point.

You can tell the difference between 304 and 316 by the sheen (but its hard when you don't have the 2 next to each other), and also by the fact that cheap 304 is slightly magnetic. If you run a magnet over it it usually won't pick up but you can feel the pull. Oftentimes when looking for 316 nuts for a quick fix at work I use a magnet.