Broken Piece Could have been Bad!!!

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One of our customers has a very large arm that picks up basically a huge vessel cap about 10k lbs. Well my boss welded the lugs onto a piece of tube and i took the piece on site and welded it in. 3 Passes with 6011 and four if i remember right on a 7018, Well my welds held and his did not so to that i say But monday morning i have to go reweld the lugs because the welds failed while the machine was in use. Its 1 1/2 plate basically. We have had to cut these lugs off and reweld them about four or five times. Shop is shut down for the week but i gotta go fix it tom. Boss man says pre and post heat it and weld the crap out of it but i am wondering if i should just burn and machine new lugs after all that heat that has already been put into the metal. Oh and his welds were a tripass using GMAW .035 wire. Let me know what yall think.
Reply:Go ahead and pre-heat if you're welding on 1.5" thick steel.  Try using a torch and heating till a 300 or 350F Tempil stick melts.  I'd pack glass wool or sand around the weld to insulate it while it's cooling.  This is all assuming it's low carbon steel.  If the cap is made from some other material, you need to find out what in order to determine the best pre and post-heat procedure.Welding those lugs on with MIG could be done, but you've got to know your stuff.  It's easy to get cold lap with MIG/GMAW.  I'm not certain, but I wonder if 0.035" wire will carry enough amperage in short circuit  to do the job.  Do you know what settings, voltage and wirefeed speed your boss used?Were I in your shoes I'd stick weld your lugs on, not use MIG.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:I was thinking the same thing. .035 isn't going to do it. I don't have a mig that big but I'm thinking 1/16 wire. Lacking a machine that large go with what you know .Good prep and 7018 all the way.  Try arc gouging the old welds out if you got the equipment. If there was any twisting or distortion in the lugs the broke free might as well make new ones.Tough as nails and damn near as smart
Reply:I would go with 7018.  I don't get the tripple pass thing, If its 1.5" plate, you need a large weld.  If its a fillet, It needs to be 1.5".  I'm thinking 15 passes, or the recomended one pass for each 1/8" of plate (12 passes)  I can look it up in the book.  Do you know what kind of steel it is?  This is important especially for the preheat and interpass temp.One weld I can remember that didn't hold was a shank on a large excavator bucket I welded with .035 wire.  I got to do it over for free. I used 7018.David Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Originally Posted by jroyster06... i am wondering if i should just burn and machine new lugs after all that heat that has already been put into the metal. Oh and his welds were a tripass using GMAW .035 wire. Let me know what yall think.
Reply:Im not sure where his machine was set. I know he uses a gobular transfer not a spray because he is real old school and doesnt believe in it. Gouger is busted but i think i am just going to take our plasma with me and use that to gouge it. Im just going to burn the hell out of those rods hot as it will properly weld. All i know is my welds held and his didint hehe! I think i am going to put a couple more more passes on the tube i welded that the lugs mount on. All i know is we are very lucky if the other lug would have gone as well someone probibly would have lost thier life. Oh yea and there goes my week off i was supposed to have
Reply:You could get by wit .045 dual shield. But even with that 1/16 would be wiser. As soon as you said .035 GMAW i knew exactly why the broke. GMAW .035 was most likely a short circuit transfer which would not put nearly enough heat into the part to get a sound weld. Like previously stated you could get by with 7018 as well. Or maybe if it's a real strong base metal some 8018 --Gol'
Reply:Oh sorry this was the only time they broke. Boss man is outta town shop is shut down so if i fab new lugs it will really be up to me. The past four times we has to reweld these was due to engineers changing the design constantly. I told the company yesterday that we had hacked this thing up so much that if there is another change in the design we will have to fab a new one. Oh and did i mention that a couple months ago this arm ripped in half, not from the welds but the tube itself. Engineers thought 1/4" would hold it didnt.  So when we fixed it they would let us rebuild a new one, they would only allow us to replace the torn mid section with 1/2 wall and weld the 1/4" back on either side of the half. Haha. This company amazes me in what they ask our company to do. All well as long as thier check clears!!
Reply:Just a quick look in the book.  Single bevel 1.5" plate with steel backer, 1/4" root.   First pass 3/16 7018 @ 240 amps.  Passes 2-22 7/32 7018 @ 280 amps, Passes 23-31 3/16" 7018 @ 240 amps.On another page, Horizontal fillet.  3/4" plate is as big as it goes up to.  5 passes 1/4" 7018 @ 350 amps.Horizontal double 45* bevel 5/32 root gap, 12 passes 3/16 7018 @ 240 amps.This isn't close to .035 wire.What was the position and joint type?Is the tube 1/4"?   or 1/2"?  1/2" weld needs 1/2" fillet.Horizontal 1/2" fillet, 3 passes 1/4" 7024 @ 375 amps.Am I out in left field?  DavidFrom the Lincoln Procedure handbook of arc welding.Last edited by David R; 11-23-2008 at 08:24 PM.Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Nope,  you're fine, but we all seem to have a different image of what's being welded to what.  Suffice it to say I think we've answered the original question...New lugs, stick welded with 7018 or perhaps 8018, and a properly sized fillet weld with suitable pre-heat, interpass, and post weld insulation.Sounds like there's an engineering deficiency at the home office, so this fellow's got to use his own best judgement on the welding procedure.  All I can say is go for it so long as you've got the skills; remember like you said someone's life may hang in the balance.  (no pun intended) Originally Posted by David RAm I out in left field?  DavidFrom the Lincoln Procedure handbook of arc welding.
Reply:See the diagram for where I'd go with it (assuming I'm reading the description right). 7018 all the way, root and all, just backgrinding the root before hitting the second side. Definately preheat to 300. Interpass 500 max. Clean up the previous welds completely, and if the material is there, into the previous HAZ to remove distressed material. Attached Images
Reply:Originally Posted by David RHorizontal double 45* bevel 5/32 root gap, 12 passes 3/16 7018 @ 240 amps.Am I out in left field?  DavidFrom the Lincoln Procedure handbook of arc welding.
Reply:jroyster06--  Is it possible to get some pictures of this thing??"Any day above ground is a good day"http://www.farmersamm.com/
Reply:Jobs like this I start with 5/32 or 3/16" 11018, then finish with 3/16 or 1/4" 11018.  Never hurts to put some extra strength material down.
Reply:P.S.  Using the big boys rods, and high amperage is going to give you a hot stinger.  Have a pail of water handy.
Reply:UPDATE::::::::Boss mans welds did not break. There was actually a 3/8 spacer on the inside of the lug where the weld was made. IT was originally in there from OEM. We never saw it till boss man just absically welded the spacer on it not the lug itself. The company wanted me just to weld the lugs back to the spacer and call it good. I said NO WAY!!!!. I went and had new Beefier lugs flame cut and spent 12 hours on finishing machine work up on them. Then my mill quit at the shop. Well i get it all done monday. Take the lugs to weld on yesterday. Then they go oh well we thought about it and we want bushings in there now. So all that machine work was a waste. I took them to a machine shop down here and he is working on them now. How do i post pics and ill put some up here.-Jeremy---THANKS GUYS!!!
Reply:I believe the "support" forum has explanations on how to upload pics"Any day above ground is a good day"http://www.farmersamm.com/