Plug Welding Plate

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Hello All,I have been tasked with plug welding .5" a36 to .625" a36 (the .625" is the material that will have the holes drilled).  I am completely in the dark on how to do this properly.   Our welder is a 300 AMP MIG.  Does anyone have any general or specific advice as to how to get this done properly?  Any help would be much appreciated.Darren
Reply:More experienced hands can probably do it w/ a round hole. I've always liked to cut a slot in metal that thick about 5/8"- 3/4" wide and 1 1/2" long so I can get 1/8" 7018 stick in and burn it in w/ the amps in the high range of the rod. Make a pass in the bottom, needle gun the slag out, make another pass, repeat 'til you've made it to the top being sure to burn in the ends real good. Then start back at the bottom making the puddle chase the slag out and work up the top again then needle gun it. Repeat as needed to completely fill the slot.                                       MikeOl' Stonebreaker  "Experience is the name everyone gives to their mistakes"Hobart G-213 portableMiller 175 migMiller thunderbolt ac/dc stick Victor O/A setupMakita chop saw
Reply:Do you know how to run solid wire in "spray transfer" mode?
Reply:for plugs i weld from the outside to the inside in a spiral for each pass being sure to pause as i come around to the start to burn it in.  as many passes as it takes to fill it up.what is the application?AWS CWI xxxx21711968 SA200  Originally Posted by WelderMike  I hate being bipolar, It's awesome.
Reply:The short answer is the larger the plug the easier it is to weld. If you are not given specifications then I would use a 1" diameter hole through the 1/2" sheet, spray transfer & fill er up!RyanMiller Multimatic 200 tig/spool gun/wireless remoteMillermatic 350P, Bernard/XR Python gunsMiller Dynasty 350, Coolmate 3.5 & wireless remoteCK WF1 TIG wire feederMiller Spectrum 375 XtremeOptrel e684Miller Digital EliteMiller Weld-Mask
Reply:See Next . . ..Last edited by OPUS FERRO; 03-25-2016 at 05:47 AM.Reason: I'm behind WW editing changes . . .
Reply:Dbiddle81 Originally Posted by Dbiddle81Hello All,I have been tasked with plug welding .5" a36 to .625" a36 (the .625" is the material that will have the holes drilled).
Reply:You should be good with a 5/8" hole, regardless if the hole is in the half inch or the 5/8". Set it pretty hot and over fill some, since it will shrink down a little. If verticle, fill from the bottom up. If flat , be sure to start in the center, to insure good fusion to the bottom plate. Removing any rust and scale from the bottom plate will help with fusion.
Reply:Removing the scale/rust on the bottom plate increases your success rate dramatically. Try your technique on some small square coupons first, then put them in a vise and twist them apart.
Reply:The biggest problem I've encountered over the years with making plug welds is trying to get away with to small a hole diameter for the thickness of plate.   Especially when you're trying to make them with stick rod.  It doesn't take to much of a buildup of the molten slag down in a steep sided narrow hole while you're welding before it will start drowning out the arc.   And then when you do stop to try and clear this excessive slag build up it can be a real PITA to chip out.Trying to make plug welds with 7018 in 1/2" plate with only a 5/8" diameter hole sounds awful tight to me.   If the hole was counter sunk it would certainly help.
Reply:Originally Posted by xryanThe short answer is the larger the plug the easier it is to weld. If you are not given specifications then I would use a 1" diameter hole through the 1/2" sheet, spray transfer & fill er up!
Reply:I do plug welds all the time. If you have  300 amp mig, then you can certainly get it to spray transfer with solid wire, but need gas with 98/2 mix.Preheat will give you very good penetration and make the welds truly like the base metal. I agree to start in the center and get good hot liquid puddle and then wash it out to deeply burn in the surrounding plate...All the way to the top and make the top a little proud...All in one continuous pass.And no, you don't need to do it spray transfer.Try a test piece.  Materials can have drilled or torched holes as long as they are very brite clean of mill scale.
Reply:Originally Posted by wornoutoldwelderI do plug welds all the time. If you have  300 amp mig, then you can certainly get it to spray transfer with solid wire, but need gas with 98/2 mix.Preheat will give you very good penetration and make the welds truly like the base metal. I agree to start in the center and get good hot liquid puddle and then wash it out to deeply burn in the surrounding plate...All the way to the top and make the top a little proud...All in one continuous pass.And no, you don't need to do it spray transfer.Try a test piece.  Materials can have drilled or torched holes as long as they are very brite clean of mill scale.
Reply:Here's an example of a somewhat modified, atypical plug weld situation where the hole doesn't get filled all the way in.   The reason for using such a large diameter hole was so that you had room to weld a dog to the lower plate and then drive a wedge to pull both pieces into just as close of contact as possible before welding.   We were just putting a 3 pass fillet around the ID of the hole and then welding in a smaller diameter cut out piece of plate in the very center with a one pass fillet.  The center piece had nothing to do with strength.  It was about forming a place that would pack full of (and hold) mineral that would then act as wear protection for the welds.
Reply:My old Lincoln handbook says the hole should be 1.5 to 3 times the plate thickness.  Larger hole for thinner plates.  1/4" plate, 3/4" hole.  1" plate, 1.5" hole. For the 1/2" to 5/8" plate, 1.125" to 1.25" hole."USMCPOP" First-born son: KIA  Iraq 1/26/05Syncrowave 250 w/ Coolmate 3Dialarc 250, Idealarc 250SP-175 +Firepower TIG 160S (gave the TA 161 STL to the son)Lincwelder AC180C (1952)Victor & Smith O/A torchesMiller spot welder
Reply:Yes, ^ that's basically what I was saying qith the short answer. (I) would probably use a 1" hole MINIMUM through the 1/2" plate and be confident I could get acceptable plug weld with my equipment using pulse/spray transfer. 1.5" hole would make it cake work. However there are a LOT of variables left out in the query, like the application?, code work?, "engineers" involved?, is there a welding procedure specification?  Etc.
Reply:This is from the D1.1 concerning prequalified joint design for plug and slot welds.
Reply:Originally Posted by HT2-4956This is from the D1.1 concerning prequalified joint design for plug and slot welds.
Reply:Originally Posted by AFFENDEwell ... i think that pretty well answers all the questions.