Sanitary Tube

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304L tube 3" OD 16g3/32" EWCe-2tack @ 20Aweld @ ~40-45Abackpurged w/ argonusing Maxstar 150I just started sanitary wtc this week. Only completed 16 joints so far so I'm still picking up consistency/speed and dialing in my best amperage.I tack at 12:00 and 6:00, then weld from 1/4" before 6:00 to 1/4" past 12:00 up one side then the other. Tacks are each passed over twice, beads are overlapped 1/2" at 12:00 and 6:00. This is how I am taught/required by my school.The problem I'm having is the hole where I break the arc at the end of a weld. My instructors simply don't know how to fix this issue, none of them ever did this type of welding in the field. I would like to eliminate this defect from my welds, any advice is appreciated.Edit:I am running the Maxstar w/out a foot pedal, just scartch start. When I break the arc I have to long arc until it breaks. I have eliminated the hole on the outside in my last few joints but I always have the hole on the inside.Last edited by hypothecary; 09-22-2012 at 12:23 AM.Miller Syncrowave 250 w/ PC-300 pulserLincoln AC/DC 225/125Clarke TurboWeld 150ENJackson Halo w/ gold lensHuntsman w/ blue lensDoing sanitary stainless tig
Reply:Miller Syncrowave 250 w/ PC-300 pulserLincoln AC/DC 225/125Clarke TurboWeld 150ENJackson Halo w/ gold lensHuntsman w/ blue lensDoing sanitary stainless tig
Reply:Miller Syncrowave 250 w/ PC-300 pulserLincoln AC/DC 225/125Clarke TurboWeld 150ENJackson Halo w/ gold lensHuntsman w/ blue lensDoing sanitary stainless tig
Reply:Zapster might jump in here, but what you have is called "cratering" at the end of the bead.  I am by no means a TIG expert but most formal defect discussions I have read say this is caused by removing the torch too quickly leaving the end of the puddle cooling too fast which causes the crater.  The same documents recommend reducing the heat slightly and slowing down as you reach the end of the bead.  You noted you are working without a pedal so you can't do as recommended above.  Try a slightly longer hesitation before pulling the torch away and breaking the arc.  The idea is to leave just a tad bit more metal deposited at the end of the bead so that as the puddle cools it does not cool to quickly leaving the crater.Zapster will flog me later if I said something wrong here. - MondoMember, AWSLincoln ProMIG 140Lincoln AC TombstoneCraftsman Lathe 12 x 24 c1935Atlas MFC Horizontal MillCraftsman Commercial Lathe 12 x 36 c1970- - - I'll just keep on keepin' on.
Reply:Can the maxstar do sequencing? I've done it with the dynasty without pedal, using the sequencer..Miller: 200dx, Bobcat 225, Passport, Powermax 45, Milwaukee: Dry Saw, MagDrill, grinders
Reply:The welds look great otherwise.  Have you considered a hand control?Harbor Freight Inverter 130 amp DC stick/tig (sold, really!)Lincoln Square Wave Tig 175 AC/DC stick/Tig
Reply:If your lifting the torch to break the arc your doing it wrong, roll out of it by laying the torch on its side and keep the gas shooting at the end of the puddle, next question, why are the welds so damn wide?I forgot how to change this.
Reply:The crater crack is from pulling the arc and gas too quickly. Ramp off the amperage until you see the puddle solidify, then pull out.Miller bobcat 225g  - spoolmatic 1Mm250 - 30a spoolMiller spectrum 375Thermal arc 95 Everlast Ex 250As the boiler turns, these are the days of our lives
Reply:does the maxstar have a down slope setting? you need about 3-4 sec downslope for that thickness/amperage . adding filler and doing some circles while the amps go down will help a lot.either that or a pedal you will never pass an x-ray with that crater.. not even visual.welds don't look bad but I would go for a 1/16 tungsten and less arc gap and bigger cup+gas lensalso.. 2 tacks may be fine for coupons, but in real world don't work.. you will have tubes with many welds/corners that will warp or just move before you get the chance to weld themI see no reason to tack at 20A--------------------------------------------------------------www.becmotors.nlyup, I quit welding.. joined welder anonymous
Reply:You have to "tail" off your weld.Decrease amps, increase travel speed and work the puddle to the edge of the weld next to the base metal of the pipe.Lincoln SA200's... at least 15 - 20. They come and go. Growing partial to the "Short Hoods" in my old age. Last count on Short Hoods was 13 in possession.
Reply:You need to walk the end of the weld in to the bead, I will take some pix for you when I get back in the plant next week. Remember guys, when doing sanitary there is no filler involved so you cant add a dab at the end of the weld.Disclaimer; "I am just an a$$hole welder, don't take it personally ."
Reply:Originally Posted by TozziWeldingYou need to walk the end of the weld in to the bead, I will take some pix for you when I get back in the plant next week. Remember guys, when doing sanitary there is no filler involved so you cant add a dab at the end of the weld.
Reply:LOL, must have, go cut out all those bad welds you didStandard practice for "sanitary" piping here is square cuts, deburr, purge, and weld. I have done heavier jobs where filler is required, and specd, same procedure just heavier piping, or vessels. Most of the stuff in the plant I do work in is under 3" and .065 wall so it is a one shot deal, no filler.Disclaimer; "I am just an a$$hole welder, don't take it personally ."
Reply:Originally Posted by TozziWeldingLOL, must have, go cut out all those bad welds you did
Reply:Thanks for all the replies, guys. I'll try to address each suggestion in order.MondoI have tried slowing just slightly as I come to the end of the weld then breaking the arc slowly. It seems this only lengthens the time spent long-arcing and makes a larger area of discoloartion around the crater.JohnRNone of the Maxstars at my school have sequencing features.AZ-BenThanks for your compliment. I have considered a hand control, I'll have to look into options.LawsonWeldingLLCI rock back to break the arc while trying to keep the arc tract within the toes of the bead then rock forward again for post-flow. I try not to loose contact between cup and tube so I won't loose sheilding. If I lay the torch on it's side I get an acr tract off to the side. Either way, this technique causes a long arc that often jumps around once or twice before going out and a crater on the inside every time I do it.My beads are 1/4" wide when I'm even and straight. What width should they be for this joint?astaindsoul5446no pedalDonoharmno downslope or pedalI'm not supposed to use filler at all. I'll have to ask about tungsten, gas lens and cup options.One instructor tells me tack every 90deg, another says 12:00 and 6:00 only. I was going with 12:00 and 6:00 to limit contamination from sugared tacks and noticed the opposite side of the joint would open while welding the first. On Monday I'll go back to every 90 deg.I later reduced amps while tacking to get less than full pen so I wouldn't have sugared tacks.hobohiltonno pedal, looking into hand controlTozziWeldingPics would be very helpful. Be nice to have a base of comparison.Miller Syncrowave 250 w/ PC-300 pulserLincoln AC/DC 225/125Clarke TurboWeld 150ENJackson Halo w/ gold lensHuntsman w/ blue lensDoing sanitary stainless tig
Reply:Originally Posted by hypothecaryno downslope or pedalI'm not supposed to use filler at all. I'll have to ask about tungsten, gas lens and cup options.One instructor tells me tack every 90deg, another says 12:00 and 6:00 only. I was going with 12:00 and 6:00 to limit contamination from sugared tacks and noticed the opposite side of the joint would open while welding the first. On Monday I'll go back to every 90 deg.I later reduced amps while tacking to get less than full pen so I wouldn't have sugared tacks.[
Reply:Ok if you don't have a amperage control. Then rock out the side of the weld slowly until the puddle start to solidify and then pull out.Miller bobcat 225g  - spoolmatic 1Mm250 - 30a spoolMiller spectrum 375Thermal arc 95 Everlast Ex 250As the boiler turns, these are the days of our lives
Reply:If you can't taper off the amperage to eliminate the crater, try reversing direction at the end of the weld bead, (doubling back over the portion you just welded,) with faster than usual travel speed before terminating the arc.
Reply:Originally Posted by TozziWelding... Remember guys, when doing sanitary there is no filler involved so you cant add a dab at the end of the weld.
Reply:Walking the cup that wide is putting an awful lot of heat into that poor tube. Do you have to walk it? Can't you just run it straight and focus on the eye swirl?Here's a 3" 16ga 304 weld with purge. I used pulse because I do automotive performance stuff not sanitary. At minimum the weld is going to be a certain width when you get to enough amps to get a weld on the inside. This weld was right about at that minimum (but then again the pulse might have made it wider on top). The face width looks about 3 times thicker than the material and the root is about 1.5x.Last edited by MikeGyver; 09-22-2012 at 05:59 PM.Welding/Fab Pics: www.UtahWeld.com
Reply:dskfjgvnksdjnfgsWelding/Fab Pics: www.UtahWeld.com
Reply:Originally Posted by MikeGyverWalking the cup that wide is putting an awful lot of heat into that poor tube. Do you have to walk it? Can't you just run it straight and focus on the eye swirl?Here's a 3" 16ga 304 weld with purge. I used pulse because I do automotive performance stuff not sanitary. At minimum the weld is going to be a certain width when you get to enough amps to get a weld on the inside. This weld was right about at that minimum (but then again the pulse might have made it wider on top). The face width looks about 3 times thicker than the material and the root is about 1.5x.
Reply:I tacked before purge, I didn't even do a very good job as there's a slight step misalignment on the 2 tubes. The tacks are hardest not to sugar on this thin tubing., and to keep narrower than the weld will be for aesthetic reasons. You need a super fast and careful pulse of power that will drive the metal from both sides together. There really can't be any gap at all or it'll require too much power to blast a tack in and it'll sugar. Just play around with it.I think the weave is completely out of a place on an autogeneous weld of thin material. Weaving makes sense when you're filling in a bevel and need to tie in the toes of each side, and it gets wider as you fill it up; maybe that's what they're training you for.Get yourself a "TIG Finger" from weldingtipsandtricks.com if you don't already ave one then you can slide your hand very smoothly w/o getting burned.Welding/Fab Pics: www.UtahWeld.com
Reply:I agree with MikeGyver, walking/weaving on thin stainless butt joints is completely unnecessary and does more harm than good. The "swirl eye" method that Mike mentioned or a short backstep works better, if its even necessary. I would also change to a 1/16" tungsten as Donoharm mentioned, you will get better results.If you don't have a foot pedal/hand control, you will never get rid of the suckback on your stops. You will also continue to have trouble tacking without sugaring.The fact that your instructors have you doing this type of welding without an amperage control and the fact that they don't know how to fix the suckback on your stops indicates that they themselves are not knowledgeable enough to be teaching it. Hopefully they allow you to move on to something else, but unfortunately you will have to unlearn all the bad habits they've taught you if you ever get a job doing sanitary welding.
Reply:Originally Posted by MechticianI agree with MikeGyver, walking/weaving on thin stainless butt joints is completely unnecessary and does more harm than good. The "swirl eye" method that Mike mentioned or a short backstep works better, if its even necessary. I would also change to a 1/16" tungsten as Donoharm mentioned, you will get better results.If you don't have a foot pedal/hand control, you will never get rid of the suckback on your stops. You will also continue to have trouble tacking without sugaring.The fact that your instructors have you doing this type of welding without an amperage control and the fact that they don't know how to fix the suckback on your stops indicates that they themselves are not knowledgeable enough to be teaching it. Hopefully they allow you to move on to something else, but unfortunately you will have to unlearn all the bad habits they've taught you if you ever get a job doing sanitary welding."In the field" if you have no hand or foot control....... You drag your work over by the machine and reach over with your free hand and tail it off.Lincoln SA200's... at least 15 - 20. They come and go. Growing partial to the "Short Hoods" in my old age. Last count on Short Hoods was 13 in possession.
Reply:Originally Posted by MikeGyverWalking the cup that wide is putting an awful lot of heat into that poor tube. Do you have to walk it? Can't you just run it straight and focus on the eye swirl?Here's a 3" 16ga 304 weld with purge. I used pulse because I do automotive performance stuff not sanitary. At minimum the weld is going to be a certain width when you get to enough amps to get a weld on the inside. This weld was right about at that minimum (but then again the pulse might have made it wider on top). The face width looks about 3 times thicker than the material and the root is about 1.5x.
Reply:Originally Posted by hobohilton"In the field" if you have no hand or foot control....... You drag your work over by the machine and reach over with your free hand and tail it off.
Reply:Originally Posted by AircamperaceMike can you explain what the "eye swirl' is?
Reply:Very nice Mike and thanks for the clarification. What kind of torch motion are you using if any?
Reply:Just running it straight and steady with no side to side or front to back movements.Welding/Fab Pics: www.UtahWeld.com
Reply:badass welds there mikemike