100% pure 7018 mild steel weld?

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In my 20 years or so of stick welding, I've learned that a 100% pure 7018 weld with mild steel is difficult at best, if not impossible. When I use to weld tanks, we were allowed a percentage of perosity. I've even seen very good code welders trying to get 100% shot with 7018, but they had to switch to tig for a perfect xray.The other day I took a simple two position plate test, 3/8, backing strip, 7018, bend. I've never failed a bend test. This company cleans the coupons and sends the pieces to be bent to another company for testing and certs. They called me and ask that I come back and re-test. They said there was some perosity evident after they cut the test strips. A few times I've seen a tad of perosity on the surface after cleaning a test coupon and simply buffed it out lightly and the plates have always bent good. But this company wants to be very sure they don't waste their money so they are being very careful about sending the coupons for certs. My question is, has anyone out there ever got a 100% pure xray or UT with 7018/mild steel welds?
Reply:its very common people weld pipe 7018 xray every day. even 7018 open root all the way out
Reply:I hold 4g unlimited bridge 7018 xray. maybe time to pop a fresh can of rods, or switch brands?migweld 250parcmate 205weldall 250piforcecut 80i plasma'07 pro 300 miller'08 trailblazer 302mm350pdynasty 700dynasty 200deltaweld 452xr-a 50ft push pull feeders and gooseneck
Reply:I can always learn something new. I'm not a certified pipe welder. But are you guys saying your 7018 pipe welds xray 100% pure, not 99%, not even one black spec on the xray film?
Reply:they can be, Ive never seen any of my films, ive been told they have been "very clean" before though.  But Im not aware of any spec that doesnt allow for at least some degree of weld discontinuity. Some specs are stricter than others though. A small small amount of porosity is usually tolerated. A structural fillet weld may allow more or less porosity than a transmission pipeline weld. It helps to know the code you are testing to. Knowing what is allowed may save you from chasing a repair that could blow way out of control.
Reply:Ive never been X-Rayed, but I know from my ( short ) experience, that Lincoln Exaclibur 7018 is the best Ive used. Which is mostly pipe welding as well... H4R I think, I hate the "generic" rods. I see some porosity with the off-brands, and its usually sitting around the trucks for a while. I would imagine that the test pieces, you were givin rod fresh out of the oven. I was. BIG difference I thought.---But Ive never taken an X-Ray test....So you cant take much stock from me...lolLincoln Power MIG 210 MP ( boat anchor )Lincoln Weld-Pac 100 HDHobart IronMan 230Cutmaster 42Jackson NexGenSumner Ultra ClampsDWM120
Reply:Originally Posted by citizen smithits very common people weld pipe 7018 xray every day. even 7018 open root all the way out
Reply:Another issue to consider....if you did in fact get the rods out of an oven question whether they had ever drawn moisture prior to you using them.  If they had drawn moisture and put back in the oven then they are no good for that type of weld unless they had been rebaked or reconditioned, and even with that I would still perfer fresh out of the box rods. I never had any porosity issues with 7018 certs, only my lazy a$$ not getting all of the slag removed!  And like has been mentioned, I have not heard of a cert that did not allow for some degree of weld discontinuity.Last edited by goinssr; 01-30-2011 at 09:51 PM.StephenMillermatic 251Miller Syncrowave 200Miller 30A SpoolgunHypertherm Powermax 30Etc., etc., etc.............Cancer Sucks!
Reply:thanks everyone for the advice. Gotta test in the morning. I'm gonna pull ever trick I know to pass this one.
Reply:Originally Posted by goinssrAnother issue to consider....if you did in fact get the rods out of an oven question whether they had ever drawn moisture prior to you using them.  If they had drawn moisture and put back in the oven then they are no good for that type of weld unless they had been rebaked or reconditioned, and even with that I would still perfer fresh out of the box rods. I never had any porosity issues with 7018 certs, only my lazy a$$ not getting all of the slag removed!  And like has been mentioned, I have not heard of a cert that did not allow for some degree of weld discontinuity.
Reply:A perfect x-ray will look completely clear or perfectly the same as the metal you are welding on. excalibur is what we use here where I am at and no problems to speak of. Originally Posted by GiterdoneThat's a good point. The rods were excalibur, but they did not look fresh. The machine they give me always started to cold, and ended too hot. I'm gonna ask for another machine this time. Plus I made the mistake of leaving the rods sitting around on the table too long. Well I'm gonna do some things different this time.But my whole point is that if they cut the test strip, buff down the weld flush to the plate, and then see one little tiny spot, the plate will still bend, if they lighty buff it out. I have seen xray film, and it's my understanding that there is always at least a tiny amount of porosity, but the limits vary with this kind of weld. This bend test allows up to 1/8 inch total crack anyway. I just think they making to big a deal out of this.Anyway, again, thanks
Reply:Hello giterdone, along with the suggestions of the others I might add just a couple of additional items. Try to be sure that you aren't long arcing at all during any point of your welding, if so, you're definiely giving  the weld an opportunity to pick-up some porosity. If you tend to manipulate the electrode any, be sure not to whip it, smooth and steady will get it done, whipping won't, you can pick-up some porosity in this manner also. I don't believe anyone likes to waste rod, however, if you are making restarts with used rods that you have "prepped" the ends of, you run additional risks of picking up porosity as well. Use a new rod for each restart, the $0.25 rod that is tossed doesn't cover the rework or lookout from a test that may result. Even restarts can be responsible for porority if the technique isn't done properly(even with a new rod), try to make your start slightly ahead of the crater and then weld over the point of strike to prevent any initial porosity, the weld bead going over the top of the start will generally allow for absorbtion of any initial porosity and allow the trapped gases to escape through the weld bead as it progresses. I know that you  have said that you have many years of experience with stick so please forgive me if you have already considered or known about any suggestions that I have given.Best of luck on your testing and best regards, Allanaevald
Reply:Code strictness dictates the time allowed for rods to be out of the oven, be it 4 hours, 2 hours, 1 hour, or less....it depends on the code. Nuclear welds, for instance, will be on the strict side of life, if you get my glow. This speaks of the importance of keeping those rods hot from the can to the weld.City of L.A. Structural; Manual & Semi-Automatic;"Surely there is a mine for silver, and a place where gold is refined. Iron is taken from the earth, and copper is smelted from ore."Job 28:1,2Lincoln, Miller, Victor & ISV BibleDanny
Reply:i believe power piping requires rod be brought from the oven very 4 hours...
Reply:I use D14.3, earth moving equipment, all position, unlimited thickness, (3G and 4G)  This allows no discontinuity greater that 1/8" measured in any direction, and the sum of the greatest dimension of all discontinuities exceding 3/32" must be less than 3/8".  I think it's pretty liberal myself, but you would be surprised with how many "qualified" welders with many years experience can blow this test.6 Miller Big Blue 600 Air Paks2 Miller 400D6 Lincoln LN-25's4 Miller Xtreme 12VS2 Miller Dimension 812 4 Climax BW-3000Z bore welders Hypertherm 65 and 85Bug-O Track BugPair of Welpers
Reply:ExpatWelder has it right.  There are always tolerances as to the allowable amount of porosity in the weld (for X-ray) and allowable discontinuity (for bend tests).  While I don't get why this particular company is sending out their coupons instead of bending them in house, you should ask what the acceptance criteria are before starting the test.
Reply:Originally Posted by aevaldHello giterdone, along with the suggestions of the others I might add just a couple of additional items. Try to be sure that you aren't long arcing at all during any point of your welding, if so, you're definiely giving  the weld an opportunity to pick-up some porosity. If you tend to manipulate the electrode any, be sure not to whip it, smooth and steady will get it done, whipping won't, you can pick-up some porosity in this manner also. I don't believe anyone likes to waste rod, however, if you are making restarts with used rods that you have "prepped" the ends of, you run additional risks of picking up porosity as well. Use a new rod for each restart, the $0.25 rod that is tossed doesn't cover the rework or lookout from a test that may result. Even restarts can be responsible for porority if the technique isn't done properly(even with a new rod), try to make your start slightly ahead of the crater and then weld over the point of strike to prevent any initial porosity, the weld bead going over the top of the start will generally allow for absorbtion of any initial porosity and allow the trapped gases to escape through the weld bead as it progresses. I know that you  have said that you have many years of experience with stick so please forgive me if you have already considered or known about any suggestions that I have given.Best of luck on your testing and best regards, Allan
Reply:Not to sound harsh, but their job was to prep the test strips not make them pass. When you see slag inclusions and start to buff it out, you don't know how deep its going to be and for a welder no bid deal just grind it out and fill. For the person prepping, they can't do that. Also you don't know how  that piece is going to bend since it already has a defect, why waste money on a test?Fengenbush the only reason I can think of for sending the samples out is maybe they have no one that is certified to asign a cert.
Reply:I see a lot of film every day, and it's extremely rare to see ANY SMAW weld that's completely clean.  The manufacturers themselves will even tell you that.  On most shots, the film density and UG can hide quite a bit of it on thick material.
Reply:I just got back from the re-test. It seemed to go well, but will find out in a couple days. I saw the first test coupons. There was too much porosity in one of the caps. So my bad.
Reply:Every day for 10 years all UT and some RT. 1-2 busts Code AWS and ASME
Reply:I have done pipe, bridge work, moment connections, etc... all with 7018 100% Always passed UT or X-ray.Disclaimer; "I am just an a$$hole welder, don't take it personally ."
Reply:I worked at a structural steel company, before I quit I gave the welding test, and then shipped them off.  We chose to send our plates out for liability and certification issues.  We did an in house test, but all our AWS certification was sent to a testing facility.  If I remember correctly we had to send our test plates out because of the AISC (American Institute of Steel Construction).  Also for the city of Las Vegas and Los Angeles city & county we had to follow the same guidelines in order to do work that would end up there.  Thats been a few years it could have changed.
Reply:Originally Posted by SeanMurphy265I worked at a structural steel company, before I quit I gave the welding test, and then shipped them off.  We chose to send our plates out for liability and certification issues.  We did an in house test, but all our AWS certification was sent to a testing facility.  If I remember correctly we had to send our test plates out because of the AISC (American Institute of Steel Construction).  Also for the city of Las Vegas and Los Angeles city & county we had to follow the same guidelines in order to do work that would end up there.  Thats been a few years it could have changed.