RebekahsZ Posted January 22, 2013 Share Posted January 22, 2013 If I plan to get the exhaust ceramic coated after it is built, is there any problem with welding 304 stainless V-band flanges to mild steel or aluminized exhaust tubing? I want the V-bands to be easy to assemble/dissassemble for many years to come, but I don't know anything about welding and metalurgy to know if there will be a problem with that welding interface with the dissimilar metals. I'm hopeful that regular gas-mig welding like exhaust shops use will be OK. Recommendations/suggestions? Quote Link to comment Share on other sites More sharing options...
ozzzzz Posted January 22, 2013 Share Posted January 22, 2013 (edited) You can do just that. The weld will rust though. Unless it is coated also. I have done it a number of times. It's not ideal but it if you want to tie into an existing mild steel exhaust system like I did it will hold up just fine.I used E70s wire in my MIG. I have also TIG welded mild steel to 304 stainless with er308 rod. It works. Again its not ideal. Some turbo manifolds use mild steel flanges with stainless runners with good results. I wouldn't worry about it if you had it done. Just my .02 Edited January 22, 2013 by ozzzzz Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted January 22, 2013 Author Share Posted January 22, 2013 Thanks. I thought it would be OK. Just have limited access to tig welders in my area. Gonna ceramic coat it. Thanks for giving me the wire specs, too. Quote Link to comment Share on other sites More sharing options...
Xnke Posted January 22, 2013 Share Posted January 22, 2013 The weld will be brittle, and will eventually crack and break under the vibration and heat an exhaust system sees. Personally, I'd get the right flanges in mild steel. I've seen stainless headers welded to mild steel flanges with standard ER70S2 MIG wire not even last a year, but most last two years or sometimes more on street cars before they break. Quote Link to comment Share on other sites More sharing options...
johnc Posted January 22, 2013 Share Posted January 22, 2013 You would better off using 309L filler for welding mild steel to stainless. It will reduce (but not eliminate) the potential for cracking and will reduce future corrosion in the weld itself. Being in Alabama, the exhaust will most likely rust from the inside out (due to condensation) so an external coating won't help a lot with that. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted January 22, 2013 Share Posted January 22, 2013 I just did this very thing... Figure the exhaust only has to last a year and said "Screw it" and welded it up. For a serious street car you only want to do this once on, I'd recommend doing what John recommended. You may also want to consider sending the pieces out to be coated. Mike Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted January 22, 2013 Author Share Posted January 22, 2013 (edited) I really appreciate the amount of input. The reason I went with stainless flanges was so that they would stay easy to disconnect for years to come (I take stuff apart often). If the welds crack-they'll be very easy to disconnect! I'll check my local welding supply store for the 309L filler. I haven't ordered my tubing yet, but I'll consider trying to get 304 stainless instead of mild steel. I was planning to use LOTS of bends because my frame notches for exhaust cutouts are at an awkward angle and I'm a psycho for ground clearance, but as usual I'm probably being a little neurotic and going overboard. I kind of hate how even stainless discolors, so I was going to send it all off to JetHot for coating inside and out, guess I could still do that with stainless, but then I'm really being psycho! Edited January 22, 2013 by RebekahsZ Quote Link to comment Share on other sites More sharing options...
johnc Posted January 23, 2013 Share Posted January 23, 2013 Jet Hot 1300 is next to useless. Go with Jet Hot 2000 at a minimum if you want a functional coating. Better yet, go with Swain White Lighting which offers excellent thermal insulation - but its not a pretty as the others. Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted January 24, 2013 Author Share Posted January 24, 2013 Thanks-will do! JetHot 2000 it is! Is 2000 good enough, or should I go for an even higher temp coating (worth the money)? Sorry, gonna stick with something that looks pretty. You guys have helped a lot. I'm gonna order some mild steel flanges for the headers themselves (exhaust pipe tubing is cheap, but I sure don't want to have trouble with my header cracking). I'll use the stainless flanges on my tail pipe sections. Next question: if I use a mild steel flange on the header, and a stainless flange on the first section of exhaust pipe with a shared v-band clamp, do you think it will have sealing problems due to dissimilar expansion properties? Quote Link to comment Share on other sites More sharing options...
johnc Posted January 24, 2013 Share Posted January 24, 2013 No. Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted January 25, 2013 Author Share Posted January 25, 2013 OK, thanks. That's the new plan. Quote Link to comment Share on other sites More sharing options...
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