Cleaning Beads Between Passes

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A question came up between me and a guy I used to work with. When running multiple passes with Stick Welding, how much cleaning is necessary between passes.   A lot of times I will see guys hammer off the slag, some times I will see guys take the time to wire brush out out the slag dust.     Is this necessary or will the crud rise to the surface of the weld puddle?  Also if you stop a bead (reposition, change stick ect), do you have to wait for the bead to cool down and clean the slag off before restarting?This might sound like a dumb question, but it is one I can't seem to find an answer for in my welding books or with google.Thermal Arc  Power-Tech 10/270  stick welderLincoln buzz-boxPurox O/A setupNothing is foolproof to a sufficiently talented fool
Reply:A lot depends on the rod use and how it's run. A rod like 6010/11 there really isn't much slag to chip, and a brush is often the easiest way to clean. It also will burn thru some slag and crud, so perfect prep isn't as necessary as with some other rods.. Other rods like 7018, 7014, 7024 for example, if you have the settings correct and run it right, the slag will self peel directly behind you as you go. In that case there is almost no chipping required. If you don't run it right, the slag deposits require a lot of chipping. Also with heavy slag like these rods have, you really need to make sure you get rid of the slag before starting otherwise you run the risk of burying slag in the bead..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:I'd say it depends on the quality of work you're doing. If you're just blowing and going on falsework, who care just lay down some metal.For code work, or testing, if I can see it, it comes out! I'll even use an awl to clean the toes of each weld before continuing on welding. I also use a flash light to help see better.Don’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Try some bifocals"I also use a flash light to help see better""Any day above ground is a good day"http://www.farmersamm.com/
Reply:Like dsw said.. It all depends on how it turns out after the bead, usually when I change rods, position, or just need to stop... I will smack my stoping point one good time to break the slag where I need to restart then keep trucking. With multy pass beads I like to break the slag off and give it a quick once over with a brush for 2 reasons..First., sometimes your slag will run and make the bead appear to be wider,skinnier,taller,deeper.. Than it is. That makes getting a nice straight cap harder to do when your watching the previous slag puddle.Second.. If you don't clean your root pass (first bead) the old flux can cause pops and splatter because it's full of the impurities from the last weld that have baked out into the slag.Good prep always helps lay a good bead!Hope this answers a few questions!Real welders know how to penetrate!(Equipment)Whatever can be used to beat my opponent into submission!
Reply:I do use the bifocals. It's called a cheater Regards,RobGreat Basin WeldingInstagramBlue weldersRed weldersMy luscious Table DIY TIG Torch cooler
Reply:It's only cheating if you get caught Robert! LolReal welders know how to penetrate!(Equipment)Whatever can be used to beat my opponent into submission!
Reply:Blue, I'll kick in one more opinion.  Like the others have already stated, it depends on the type of welding electrode, process, and the quality required in the work.  I'll enlarge on what CEP said about using a pick to clean the toe lines...If the bead in question is flat and makes a smooth, gradual tie-in to the base metal, then cleaning is easier, and often less critical.  Sometimes the slag will self-peel.  On the other hand, if a weld bead is very convex, with a tight crevice on either side of the bead, then cleaning can be essential; up to and including grinding back the center of the bead to open up access to any toe line crevices, or 'wagon-tracks'.In short, it depends.Speaking for myself, I always make some attempt at cleaning off the slag from a stick weld.  Even just dragging the point of a chipping hammer once over the slag coating is better than doing nothing.  Typically I'll use a wire wheel in an angle grinder on most everything.  If I'm having a bad day, or the weld is particularly difficult to make, then it's a hard wheel followed by a wire wheel.  If I'm welding a joint and it'll take more than one rod to complete a pass or layer, I'll just clean about 1" behind my last stopping point.  When the whole layer is done, I'll thoroughly clean the entire weld deposit before starting on the next layer.  Typically there's no need to wait for anything to cool; unless the base metal is hotter than the inter-pass temperature limit called out in the welding procedure.  If there is no procedure, then I generally take a break anytime I see the metal next to the weld taking any dark blue or purple heat tint.  This would suggest that the base metal is over 500°F.  (check out a temper color chart for more info on this)  When steel gets this hot even mild steel gets more difficult to weld; slag doesn't freeze the same and the puddle gets harder to control working out of position.  If you're welding on higher strength materials welding with the base metal so hot delays cooling off or freezing the weld beads.  Speaking very generally, this can produce a weaker weld.  (Think goldy locks and the three bears...welding too cold is bad, and so is too hot. ) Somewhere in the middle, about 300°F is just right for most steel alloys.  That said, there can be exceptions, like very thick plates or certain high alloy materials like some chrome-moly and tool steel alloys.Last edited by A_DAB_will_do; 08-27-2014 at 11:22 AM.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:turn it up hot and burn it out. That arc is like 9,000 degrees. (?)
Reply:I have an old "Sioux" electric needle scale gun followed by a wire wheel is the way I've done it. I figure clean is good so do the best I can to keep the weld area that way. The needle scaler really gets rid of slag in a hurry and a lot of times the stopping point slag pops out from the rapid vibration. I learned that trick from a well respected "old timer" in the shipyards.SlobPurveyor of intimate unparalleled knowledge of nothing about everything.Oh yeah, also an unabashed internet "Troll" too.....
Reply:I like needle scalers too.  But I have also seen them mis-used.  You can move metal around with them and I've seen guys actually bury slag by pushing a crevice opening shut using a needle scaler.  I'm not saying they aren't good to use, I'm just saying they need to be used correctly. Originally Posted by SlobI have an old "Sioux" electric needle scale gun followed by a wire wheel is the way I've done it. I figure clean is good so do the best I can to keep the weld area that way. The needle scaler really gets rid of slag in a hurry and a lot of times the stopping point slag pops out from the rapid vibration. I learned that trick from a well respected "old timer" in the shipyards.
Reply:Originally Posted by Robert HallI do use the bifocals. It's called a cheater
Reply:Originally Posted by A_DAB_will_doI like needle scalers too.  But I have also seen them mis-used.  You can move metal around with them and I've seen guys actually bury slag by pushing a crevice opening shut using a needle scaler.  I'm not saying they aren't good to use, I'm just saying they need to be used correctly.
Reply:Currently I use a wire wheel as my "wire brush", I'll typically knock the fragments off with a chipping hammer then go to town with the wire wheel, then inspect it to see if further actions are necessary.Hobart Stickmate LX235AC/160DCRanger 305GVictor 315 O/A rigHope to acquire in the next couple of years: Hypertherm PM45 and Dynasty 200DX
Reply:I use my needle gun. With 70XX I just wish it off and POOF *On outside work it was the painters problem Bubble gumTooth pixDuct tapeBlack glueGBMF hammerScrew gun --bad battery (see above)
Reply:if i'm on a job where the welds are going to be x-ray or ut tested i'll use an air powered chisel or jitterbug to remove the slag on multi pass groove welds and a wire brush to clean all traces of slag or dust. i was just on a job last saturday splicing H beams and the inspector was just doing a visual so a hand powered chipping hammer and wire brush was plenty.i.u.o.e. # 15queens, ny and sunny fla
Reply:Thanks for all the replies.   You pretty much confirmed what my gut instinct was telling me.When I first started welding, at my last job, the guy who showed me how to use the welder, said if you were made multiple  passes,  you didn't have to worry about the slag,  the second pass would burn through.   The problem was,  we weren't running 6011, we were running hardfacing rods, building up teeth on a mulch grinder.  (running as low an amp as we could,  so we wouldn't melt the edges of the tooth)      The next thing he said was you can't build them up too much, cuz the hardfacing had a tendency to chip off.     When I climbed into the grinder and looked at the chipped teeth,  it was pretty easy to see,  even to my very novice eyes,  that the reason the hardfacing was chipping was all the slag iclusions.  So I decided to do an experiment, and lo and behold, the teeth that we cleaned the slag between passes, didn't chip/shatter, like the teeth the other guy did.   I'm sure, if we knew what we were doing, and not making it up as we went along,  we could have gotten even better wear out of the teeth.    Now that I found this place,  I can figure out if what I've been told is actually right,  or is just some self-taught farmer/mechanic BS that's gotten passed on down the line.Thermal Arc  Power-Tech 10/270  stick welderLincoln buzz-boxPurox O/A setupNothing is foolproof to a sufficiently talented fool
Reply:I have a big half round bastard file with teeth ground into it that works well . You can also use a large one inch wide hacksaw blade.
Reply:Clean the slag after each pass, regardless of what rod your using. It makes it easier to put in the next pass. Do quality work 100% of the time. No shortcuts.JasonLincoln Idealarc 250 stick/tigThermal Dynamics Cutmaster 52Miller Bobcat 250Torchmate CNC tableThermal Arc Hefty 2Ironworkers Local 720
Reply:If you don't clean off the slag after each pass, then after the weld is finish just think of all the impurities in your weld. I don't know about you, slack job or not I can't feel good about my work if I know I'm not doing it right. I would say to chip off the big slag, and then use a wire wheel with a small grinder and just go over once.   6011, 6010, 7018. Whatever rod you're using, I would clean it regardless.
Reply:Originally Posted by TatcleabdzIf you don't clean off the slag after each pass, then after the weld is finish just think of all the impurities in your weld. I don't know about you, slack job or not I can't feel good about my work if I know I'm not doing it right. I would say to chip off the big slag, and then use a wire wheel with a small grinder and just go over once.   6011, 6010, 7018. Whatever rod you're using, I would clean it regardless.
Reply:If I have my choice, I scrape off the slag and hit it with the wire wheel. If I have any doubts about the toes being clean, I'll give em a pass with a 1/8" grinding wheel just to make sure. A little LED flashlight sure helps out too. If you have a wire wheel and grinding wheel with the hub nut built in, it only takes a second to switch between the two. A lot faster than grinding the whole weld out later on.IW Local 580 NY, NY
Reply:I chip between the passes, using grinder occasionally in the toes if I am having an off day.If it is true that you can boil flux slag out of a weld while laying in the next rod, then in the end there should be a gigantic pile of slag as one piece assuming multiple rods are used.
Reply:Its a pretty cool process, only time i've ever slag welded is when im "buddy welding"  you have one welding machine, two stingers hooked to the one lead.  One person each side of the boiler waterwall they call it, a guy on one side lights up, brings it around as far as he can , you on the otherside "steals the arc" around the corner , starts working around the other side.  Guy on the other side reloads another rod, picks you up when you get to the point you cant see again, and so on, if slag welding it will usually be two maybe three stringers like this, I like to stop before the final stringer and let the tube cool as its real easy to undercut at that point.  The tube is usually red hot at this point. I prefer not to slag weld, but every now and then i'll get a partner that isnists we do it that way. Not sure if that was a good despcription of the buddy welding  process and slag welding process , but its kind of hard to explain if you've never been in a boiler.
Reply:I always try and get the slag cleaned up as much as possible. I usually just use a wire brush on my grinder to quickly remove the slag before doing another pass. Even if I'm not running a second pass I will use the wire brush on my grinder to remove the slag. Works faster than the hand brush. ChadFor me still in the beginner bracket I need all the help I can get and welding dirty doesn't help me at all. I knock the slag off every starting point and multi pass clean it all. Like snoeproe says " Do quality work 100% of the time. No shortcuts." I have seen pipe welder in the field running 7018 not touch a start point except with the next rod (cleaning between fill passes) and it pass X-ray.Ranger 250 thick stuffHobart Handler 140 not thick stuffthe pane and oxy setup
Reply:Originally Posted by BlueArcIf I have my choice, I scrape off the slag and hit it with the wire wheel. If I have any doubts about the toes being clean, I'll give em a pass with a 1/8" grinding wheel just to make sure. A little LED flashlight sure helps out too. If you have a wire wheel and grinding wheel with the hub nut built in, it only takes a second to switch between the two. A lot faster than grinding the whole weld out later on.