SS MIG with c25 gas question

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I have a friend at work who wants me to make a small box from steel or stainless. It would be about 14ga sheet. It will be a pump housing (full of water) for a lawn water feature of some sort.My question is: if I get a roll of SS wire for my MIG, and run my current gas c25, will it work?I am leaning toward just using steel and painting it well. But I am curious about the SS.This project is not worth me getting another bottle of gas I don't think.RyanLincoln PowerMig 180cVictor O/ABandaids and aspirinI don't know what I don't know!?
Reply:I did some reading of past posts.....I think I will just convince her to use steel.Lincoln PowerMig 180cVictor O/ABandaids and aspirinI don't know what I don't know!?
Reply:Personal feelings based on my experience only.If you're going to the expense of using stainless material, use stainless filler and the correct gas (tri-mix preferred)Last year I had to repair a substantial portion of bridge railings on a 55' trawler.The original welds had started to fail and someone had tried to repair them with mig, SS wire and (I suspect) C25.  Every weld that had been rewelded had rusted thru and failed.  Took longer to grind out the old crap (rusted filler) than it did to reweld.If you want to preserve the "stainless" properties of the base metal, use the right gas.  If not, use mild steel, prime and paint properly.Just my .02Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:I am split on my thoughts here; the SS will hold up better. Steel in the ground will get attacked quickly by the minerals in the soil. SS would not last forever in this condition either, but it would last longer. If you did the SS box, then I can suggest after having done a lot of mig on SS that you will get a decent weld out of it with the C25. I would recommend you polish the welds when done; it will help leave a finished surface that will fight corrosion better than just welding it and putting it to service.Other options are to get some Herculiner urethane and coat a steel box well with it, several coats. It holds up to the elements very well FWIW.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:Would C10 do a better job on SS than C25? (if Tri-mix was not an option)-az-
Reply:Redneck,I do a fair amount of SS mig (marine repair/fabrication) so I keep a 330 bottle of tri-mix on hand and that's worked well for me.  My feelings are, if it works don't change it.OTOH, if I didn't have the tri-mix on hand, I'd just tig it and be done.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:Let someone TIG it up for you. If you set it up properly, what is he going to charge you? Especially if you are a welder yourself. I would say give me whatever you like. Usually they throw a twenty on the table. You can TIG that up in five minutes. MIG on stainless is a bit cold and dark grey in color.        Sincerely,             William McCormick
Reply:the maximum allowable CO2 content for stainless welding is 2-5% C10 won't cut it.  Tri-mix while nice is not neccessary 100% argon can be used (alhtough it's sluggish and penetration is low) alternatively 98-2 with the 2% being oxygen or co2 will also work just fine.I use 98-2 to penny pinch.If you get excess carbon in the stainless steel from using CO2 you sensitize the Stainless steel, which will actually corrode faster in most conditions than straight steel.  Either do it right, or don't bother at all, you would be surprised how fast those welds will rust out and start attacking the base metal.If it's just a cistern or water holding container for room temperature you could get away with steel, or paint it depending on how critical it is.  If you want to make it out of stainless TIG it or spend the money on the 98-2 or tri mix to do it properlyWelding EngineerCertified Scrap Producer
Reply:Use the appropriate materials and methods for the job.That may mean plain mild steel is appropriate if painted and sealed well.  Or some other material for the water tank.If the job calls for stainless, use the appropriate filler for stainless and the appropriate gas for stainless and the appropriate process.  That may be some stainless steel SMAW, or some stainless steel GMAW with the appropriate shielding gas (which will -rarely- ever be C25 or CO2, more often it would be a tri-mix or maybe some 98-2 for spray-mode), or maybe some GTAW with pure argon.Do it once and do it right.  Using an inappropriate material or filler or gas or process is NOT doing it right.  See above about the tale of the rusted out SS marine handrail.  And remember that stainless steel is stain LESS, not 'this steel will never rust or corrode no matter what'.  Certain things will make stainless corrode or not corrode more/less.  Cleaning and polishing stainless steel can greatly slow down the corrosion process (less surface area on a microscopic level for corrosion to start, among other reasons).  Leaving the stainless steel rough or using not-really-stainless materials can lead to a much greater corrosion rate.  Leaving a rough, poorly welded, overheated, plain steel weld filler with CO2 as the shielding gas on a GMAW weld on some stainless steel will turn things into NoLongerStainlessSteel.  Sometimes rather rapidly.Redneck, C10 is not really a shielding gas for short-circuit transfer GMAW.  It is used for spray transfer.  Or maybe globular.  C15 is about as low on the CO2 percentage as you usually go and still do short-circuit transfer.  The tri-mix is different because the small amount of CO2 is there with some helium as well as the bulk argon, and thus is still in the parameter range for short-circuit transfer generally.Single-pass GMAW with up to about 5% CO2 (C5) usually doesn't put too much carbon into the weld to interfere with the stainless steel filler and base metal.  Multi-pass and/or more CO2 in the shielding gas puts more carbon into the weld, and that usually means things turn out less stainless than thought or desired.  YMMV.  So even using 'good' 308 filler onto some 304 parent material will probably give you rusty welds if you used C25 instead of a low-carbon gas like tri-mix or 98-2 argon-O2 (no carbon there obviously).Use a plain carbon-steel wire brush (hand or powered) and you can put enough non-stainless into the area that you get rust more/faster than thought.Do it right and then you don't have to worry about it.  That's part of what the filler manufacturers do, they figure out the appropriate filler and process and gas for different uses.  Sometimes there are several ways to do a 'good' job, sometimes there may literally only be one filler that is appropriate for the parent material and that in turn may dictate the shielding gas and process to use.  The best laid schemes ... Gang oft agley ...
Reply:If you do it in steel, you can also have it hot zinc dipped or zinc flame sprayed.        Sincerely,             William McCormick
Reply:Thanks for the great info gents. I will let you know what we decide.RyanLincoln PowerMig 180cVictor O/ABandaids and aspirinI don't know what I don't know!?
Reply:look at some of the epoxy coatings out their. It's more like a rubber dipp than paint. Might work out rather well for this application if you chose to use mild steel