Mig welding stainless suggestions

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Hey guys, i have a project coming up where i have to do some mig  welding on 1/8 inch thick stainless steel tanks, the owner needs the welds to be rust proof and polished(smoothed). Im using a hobart 210 mvpWhat setup would i need? Wire? Gas?Polishing tool? grinder? and Wheel? they are all fillet welds around 6 inch pipes...I am open to suggestions and pictures. Thanks...
Reply:Originally Posted by Cdavid82Hey guys, i have a project coming up where i have to do some mig  welding on 1/8 inch thick stainless steel tanks, the owner needs the welds to be rust proof and polished(smoothed). Im using a hobart 210 mvpWhat setup would i need? Wire? Gas?Polishing tool? grinder? and Wheel? they are all fillet welds around 6 inch pipes...I am open to suggestions and pictures. Thanks...
Reply:Originally Posted by dave powelson"fillet welds around 6 inch pipes..." on .125 wall ss, may raise some nice distortion issues,depending on the end use of the tanks, the pipes, support of the pipes, design of the modified tanks.Some definitive pics, sketches or descriptions of what you're planning would help.If the tank & pipes are 304 SS, 308 wire with tri mix.If sanitary welding is required, inside and outside of the tanks, please say so
Reply:Originally Posted by Cdavid82Well, these tanks have like an 8 foot diameter and the pipes run from one side to the other, so basically i am going to cut out two holes on opposite sides of tank and run the pipes straight through. the pipes will have heater elements in them and yes it is for sanitary use... hope this helps.
Reply:Well i bought a pice of 1/8 plate and 16 guage pipe and did a practice run. I mig welded around the pipe then i ran a second pass crossing over the first bead Kind of like an "EKG", sorry i work in the medical field as well. so i reniforced the welding and i just made it alot easier to grind and polish, im pretty happy with the result, Check it out, i appreciate all ur inputs. i ran like a 5 inch bead for example purposes. go easy on me now...Oh and i know it still has some scratches but i only went to 60 grit flap wheel, itll come out smoother with 120. any suggestions on flap wheels for this?Last edited by Cdavid82; 07-24-2012 at 09:25 PM.
Reply:If you size your pics to 800 w x 600 h pixels, the text won't be cutoff as it is now.Stated customer requirement is no rusting, which can occur without back purging andgood heat control on SS. Loose control of the heat input, the SS is permanently degraded, carbideprecipitation, etc.It appears there's some melt-thru on the ID along with good oxidation....so either you don't knowor don't care? The front side examples are not sanitary welding or finishing.Blackbird
Reply:ok, what is the "front side"? and no, in this case i dont care about the burn through, i am focused on the finishing of the fillet welds. So what is considered sanitary?
Reply:Well i bought a pice of 1/8 plate and 16 guage pipe and did a practice run. I mig welded around the pipe then i ran a second pass crossing over the first bead Kind of like an "EKG", sorry i work in the medical field as well. so i reniforced the welding and i just made it alot easier to grind and polish, im pretty happy with the result, Check it out, i appreciate all ur inputs. i ran like a 5 inch bead for example purposes. go easy on me now...Oh and i know it still has some scratches but i only went to 60 grit flap wheel, itll come out smoother with 120. any suggestions on flap wheels for this?Text for pics above
Reply:Well, It's been 10-12 years or so now, but I built/modified TONS of stuff llike this for Odenberg foods (potatos) and Del Monte (tomato paste).  First off, what kind of SS is it?  304 is common for food industry. For food or sanitary, you'll likely be welding inside and out. I seem to recall using 316L filler wire, as that's low carbon for rust resistance. This stuff is usually TIG work, you'll have trouble later cleaning up the MIG welds, and pray that you don't get any spatter.. If you MIG it, go with .030" wire, and the Helium Tri-Mix. That gas is very expensive. You might be better off renting a small Tig inverter and air cooled torch, and use less pricey 100% Argon. you don't really need (or want) a lot of current  for the stuff you're talking about.   I'd plasma the holes undersize, then carbide cutting tools, or dedicated abrasives. Cover everything with sticky backed plastic film, once you do anything to mar or scratch the SS surface, it's very difficult to make it look good again.  SS wire 'toothbrushes' are good for cleaning the oxide off later, or use ferric chloride, polishing I've used the industrial 'Scotchbrite' pads.  Sorry I have no pice of the tanks, they were about the same as yours. I built about 12 of these Augers, 24" inside about 20 feet long.  And, I could be completely wrong about all this welding stuff, BUT if you ever ate french fries, they probably were processed by Odenberg, in Idaho.  If you're impressed at all by this auger stuff (one man job too) ask for a few pictures of the Green Bridge I designed, built and installd. Attached ImagesDougspair
Reply:Nice job, you seem to know what yout talking about. i also have a miller diversion 180 tig, but the positioning is to uncomfortable and its 8 of these tanks, i can get  the job done faster with my mig. no fluid is going to go through the tubes, just heater elements, the pipes will heat up heat and hair products that are made in these tanks. So the main part for "sanitary" is that  the welds are not porous?
Reply:And now this....Well done TIG welds are most often accepted 'as is' by most customers, inspectors. Control the heat, good gas flow, you'll get nice shiny welds with no oxide.  Here's a 1/8th pipe bung on a heat exchanger for temp probe, I wasn't going for the cosmetics, just everyday stuff. Oh yeah, using 30+ year old AIRCO welder that was junk. Attached ImagesDougspair
Reply:TIG welding is seldom 'comfortable' which is partly why guys get the big $$ for it.  ,No 'good' weld will have porosity, and sanitary means no voids, cracks, crevices, blind threaded holes, of any sort. No spatter or scratches. Even hair products are likely going to be covered by some sort of food/health deal with the welds. I'd weld inside and out, no worries about a problem later. The TIG will save you HOURS of labor later, over the faster MIG, trust me... I've never, ever met anyone who said, "I like to grind!"   I'm 65 and seen a lot of 'shortcuts' that ended up being a very long and pricey road.  With TIG, when you finish making the weld/bead, and set down the torch, you're pretty much done with the job.  'Just sayin' Ya' know?  OK, here's some tanks, 304SS, 1/4" wall, 20 feet long 78 inches OD, bead blasted after, for Odenberg. I made about 20 of these. MIG welded, but the appearance wasn't an issue.  If you do go with the MIG, you should get a brand-new dedicated liner for the MIG gun. Don't ever use it for any other material. Same for any wire brushes or sanding materials, they'll get steel dust on them, then it can be transferred to the SS and rust spots appear later. Use only SS wirebrushes too. Attached ImagesDougspair
Reply:ok thanks for your advise, you sure gave me usefull information, thank you again
Reply:Doug,Hi, I would like to see your Green Bridge photos, as we discuss this stainless oxidation issue.Thanks,Jeff
Reply:Cdavid,What the guys are trying to tell you (politely), is that you're going to be hard pressed to achieve a true "sanitary weld" using the mig process.Careful prep and tig welding will eliminate most of the post weld effort and result in a better finished product.You got to realize that when you start a thread the way you did, the experienced guys will always question your capabilities.  History has proven that when a guy starts a thread with, "what wire, what gas, what setup", he probably shouldn't be attempting the weld.High dollar equipment like you're dealing with here, is not where you develop your skill.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:Well im going to go with the tig idea, i was just trying to get the work done faster, mig the whole bead, polish and go, but i see thats not the case, my concern was that the tig bead was to thin in this case and wouldnt give me enough weld to shape and polish nicely. What do you guys think about the metabo fillet weld polisher? The finishing part is my main question in this sanitary project. i know these tanks have factory welds that are not tig welds,they look like polished mig welds, i was just trying to replicate what i saw. thanks for you opinionsOh and Sorry i started the thread in this fashion, but ive mig welded for quite a while, but never with tri mix or stainless wire. My family owns a muffler business and ive welded quite a bit of stainless mufflers and tips to regular aluminized pipe. but never stainless to stainless with stainless wire.Last edited by Cdavid82; 07-25-2012 at 09:29 PM.