Stainless electrode choice

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Guys, I'm not new to welding, but I have 2 questions because i'm cheap and don't want to buy the right electrode!  I'm building an exhaust manifold and i'll be stick welding 304 to 316 and 304 to 304.   1.  I'm guessing the choice electrode (if i were to buy one for both welds) is a 309 electrode, but I already have some 3/32 electrodes marked 310-316L. Will the 310-316L make an acceptable weld as far as strength & corrosion resistance?2.  Would it be worth my time to use Solar Flux on the inside of the tubes vs. argon purging?Thanks for any help!
Reply:hmmmm "stick welding?"..."argon purging?"...now you even have me confused... i've never used argon with a stick welder..anyone else?...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:I'm new to welding stainless; I have a tig torch for my stick welder (hence, the argon).  I just didnt know if i need to protect the back side of the weld (even using smaw).  educate me....
Reply:so your going to stick stainless ??  or are you wanting to use 309 filler   tig  is cleaner !!   WHY stick weld SS exhaust tubingwhen you have tig ? my self  would tig   I am  like  Zap  **corn--fuzzzzed**  gas with stick  dont think it would help
Reply:The normal choice of filler for both 304 and 316 is 308.  309 is also good, but more expensive and not required.Not familiar with the 310-316L designation, don't know, is it 310 or 316?  Either way, it should work just fine for your application.  If this was a highly corrosive, high pressure chemical process line I would research it more, but your 304/316 manifold is going to be quite forgiving in terms of weld quality and corrosion.As far as purging the inside, good question.  I suspect you would prefer a smooth clean underbead as compared to a rough oxidized sugared ID with compromised corrosion resistance.With TIG you would purge. With stick, I'm not sure.  I think with an open root, the underbead is protected enough by the electrode shielding to be acceptable.  With a tightly butted joint and stick however, if you are not burning a keyhole as you weld, the back side will not be shielded by the rod, and the melt-thru will sugar.Basically, a good smooth full penetration stick weld on manifold thickness tubing is going to be very difficult, where as partial penetration will be easier, not full strength/but probably ok, and yeh you could purge.\So after all that consideration, I'd purge and TIG it, this gives the best shot at the highest quality job.
Reply:Ok i gotcha...Here's the deal, I've only tigged a couple of times and i'm not real fast or good at it.  stick on the other hand is a whole lot faster and better looking for me right now.  my machine is an old stick machine with just a tig torch attached (scratch starting & no foot pedal).  the tubing is .065 wall, so i don't think i will have that much trouble welding it with a 3/32 electrode.  thats why i was asking about the solar flux or gas purging, i didn't know if the thin wall made a difference on weld strength from inside contamination.  my apologies on the 310-316L electrode it should have said 310-16.  bearing that in mind, i am thinking about just using the electrodes i have and call it a day.
Reply:Instead of purging, just throw some Solar Flux in there.  It's way easier and prevents the crystalization of the backside of the weld.  310 should work, as should 309L.  Those two electrodes can join most stainless alloys including dissimilar stainlesses and stainless to mild.
Reply:what he said.
Reply:I've been working on a  project recently stick welding a patch onto a steam table from a friends restaurant. It is 304 stainless and 20 or 22 gauge (kinda thin). I'm struggling with the project due to deformation of the thin stuff (I'm using a thicker patch to put more of the heat to it and try to flow it onto the thin stuff), but can comment on the electrode selection.I'm using 3/32" 308L-16 (Lincoln Electric Red Baron AC/DC) solely because the local welding supply shop had an open box of them. I only needed ~ 3lbs (between a mock up attempt and the actual job) and everyone else wanted to sell me 6 or 8 lbs. (a whole box) which would have been a waste.I originally started out using a cheapo 110V AC stick machine and had major issues getting the electrode to start arcing, keeping it arcing steadily, and sticking. I ended up frying that machine so I picked up a 110V inverter powered DC machine (another cheapo). Man, what a difference! The inverter box has hot start and a 15% arc force so the electrodes arc immediately and burn consistently. I would be done with the project if I would have had that machine from the beginning.Anyhow, the 308L-16 electrodes work like a charm, slag comes off pretty easily, the welds look pretty good, and they are relatively affordable (I got them down to ~$10/lb).Good luck,Dave
Reply:308 is the best choice for 304-304 but does not work so well when 316 gets involved.