Grinding welds flat?

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I'm new to this forum and fairly new to welding.  I'm self taught, I've read the welding handbook from Lowe's and as much information as I can find online and I've been practicing with a Lincoln WeldPac 3200HD that I bought at Home Depot.  I'm using 25/75 mixed gas.Assuming that my weld got full penetration and is a good weld.  Is it ok to grind the weld flat for a better appearance before painting?I'm building my second project now, a welding cart.  On my first project I built a stand for my bench grinder.  I did not worry about the appearance of the weld on that one, and I didn't have my grinder mounted anywhere yet.  I want to make my cart look better though.  I have really enjoyed reading these forums and have spent countless hours at night reading back in the threads.  If this has already been talked about then I have not found it yet.Thanks,Major
Reply:No problem with grinding welds before painting..If your happy with the results then by all means grind away!Its nothing "new".....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Thanks Zapster.
Reply:I rarely grind my welds.  They are there for a reason.  I always figured why make the job harder.David  Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Any time you remove metal you make it weaker to a point. If you are not grinding into the original metal and you got good penetration it should be fine. If it were on a part that was going to be stressed I wouldnt remove the top of the weld. I like to see the weld most of the time, unless it is one of the big gorilla welds. I have been known to make those from time to time. A nice bead looks like you knew what you were doing. There are alway exceptions to wanting to see the weld bead. If you weld up a fender or somthing of that sort that you are going to paint, you would grind the weld off flush and fill the grinder marks.
Reply:This is for steel only and not for piping and pressure vessels. The welding rods you use on mild steel are all stronger than the parent metal. If you have good penetration then you can grind the surface flat and get a good apperance without problems. Don't gouge your work with the grinder. I've built a lot of tool boxes and rigged up up quite a few trucks. I liked to grind the welds that you could see flat and finish with a 36 grit sanding disc, the ones from the WS, not the paper ones from Lowe's or HD. When finished it makes a profession, shop built look. It doesn't take very lomg if you are careful not to build up your welds too much.
Reply:Thanks guys for the input.  Since I'm very new to welding, my welds are not real pretty and flat.  But I ground all the way through some practice welds that I did and I do believe that I am getting full penetration.  So what I understand from your input is, if I were building something that was to hold pressure or would hurt somebody if it failed, then it is better to leave the weld untouched.  Otherwise it is ok to grind away all those ugly weld beads for a cleaner appearance.
Reply:Basically, yes. Codes for pipe and vessel call for a certain amount of buil-up on the cap.
Reply:As said, in a word, yes. A few more words, as said, avoid going under flush unless you need to.A few more words: A weld ground flush will be often be better in severe service than an unground weld due to the elimination of stress risers at the weld toes and on the weld surface (the groove where the weld meets the base metal, even if there is no undercut, and ripples in the weld metal itself), but this is a concern only in limited cases. The typical welder never needs to worry about it.
Reply:Reinforcement does nothing for a weld. You can grind it all off if you like as long as the effective throught is the correct size. --Gol'
Reply:NEVER grind a weld.  The profile of the weld bead is a structural part of the weldment. Welding inspectors actually measure the profile with a welding guage.If it is a decrotive or cosmetic type thing, its ok as long as that weldment will NOT be put to a test. such as lawn furniture, barbeque grill etc.,.I am a welding inspector.
Reply:Is it the rule that most reinforcement should not exceed 1/8''?
Reply:Originally Posted by Donald BranscomNEVER grind a weld.  The profile of the weld bead is a structural part of the weldment. Welding inspectors actually measure the profile with a welding guage.If it is a decrotive or cosmetic type thing, its ok as long as that weldment will NOT be put to a test. such as lawn furniture, barbeque grill etc.,.I am a welding inspector.
Reply:Yes 1/8" is typical. But Donald if you have a v grove that is welded fully to code, perfect penetration there is absolutly no reason why you can't grind all of the reinforcement off of it. You will still pull the same loads under tensile. Reinforcement does nothing for a weld. --Gol'
Reply:Originally Posted by Go1lumYes 1/8" is typical. But Donald if you have a v grove that is welded fully to code, perfect penetration there is absolutly no reason why you can't grind all of the reinforcement off of it. You will still pull the same loads under tensile. Reinforcement does nothing for a weld.
Reply:Originally Posted by Donald BranscomIn a certain sense you are right, but you still are NOT allowed to grind a structural weld.If you want a flatter profile there are options. for instance the selection of welding electrodes can produce a flatter weld profile without grinding. TIG welding produces a very flat profile. The 60's series electrodes do not have a lot of deposit.A weld profile has a TOE and a FACE and the ROOT. The root is the distance from the face to the bottom of the vee groove (root) and that distance is critical.If you are welding the deck of a boat and you have a continous weld of 7024on the top  of the deck  (deck to bullwork and hull) you may want to grind that weld smooth for reasons that are about corossion prevention. If the deck is welded top AND bottom continously that will work. There are some situations where it is allowable.
Reply:He was referring to a welding cart and a grinder stand. Neither is something that is going to fall on your head or blow up in your face. By the way, how long you welding inspectors been welding?
Reply:Originally Posted by OldtimerHe was referring to a welding cart and a grinder stand. Neither is something that is going to fall on your head or blow up in your face. By the way, how long you welding inspectors been welding?
Reply:Originally Posted by zapsterI've done stuff that had to be ground flush after per print....zap!
Reply:There's not a weldor alive that hasn't grinded his welds at one point or another.  I deal with situations daily that the welds have to be ground flush for various reasons, and never had a problem.  I generally don't unless it has to be for some reason, but I've never seen a ground weld not hold up that was welded right to begin with.I'm a Lover, Fighter, Wild horse Rider, and a pretty good welding man......
Reply:When I took the 3G test, they machined it flat before bend testing. I still don't grind welds unless its cosmetic or if something has to fit flush.If you are grinding off ugly beads, work on making them look better.  To each his own.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:Im a novice solder compared to most here and I did grind my "booger or monster" welds when I first started welding for a clean look. After a year I don't and I think this will improve your bead quality because it's kind of like hanging your package out for everyone to see!!!!...Seriously now, I am building a winch mount from sections of plate and I did grind the bead own. I have to make the winch mount top flush for the winch plate and flush on the bottom for reinforcing. Otherwise I do not.Dan"No package" My instructor said someone will catch on fire during class...He wasn't joking!!
Reply:I am a welder and I have built tube heads (API Code heated pressure vessels) where all welds had to be ground flush per design specification, and then were subjected to 60,000psi hydro testing. No welding inspectors required. If you can pass a g6 schedule 80 pipe test to 70,000 psi you can offer welding advice. I have only met 2 inspectors who could. One is on this board though his job title was a lot longer than welding inspector.No offense to you John as you know welding far better than most inspectors I have met (I do know a couple who can pass the same tests the welders have to) and I have never seen you offer any incorrect information, but you are definitely the exception to the norm. I even seem to remember seeing you climb all over one who claimed to be an inspector who was dead wrong in what he said (I think it was Donald in fact but could be wrong). In fact something tells me you might be a little bit more than just an inspector. In code work all parameters of the weld are specified including the allowable reinforcement, bead width, and amount of allowable surface grinding. I don't know of any codes for welding carts, LOL. Ninety percent of the tests I have taken were destructive testing and I have even administered a few of them and be it bend testing or pull testing the welds are always ground flush. If properly done the base metal will always fail before the weld does. I have had welding inspectors ask me numerous times what electrode they should use or what type of joint they should use on their home projects. My standard response is "I don't know". I just feel if you can't do it you aren't qualified to critique it. The day is coming when I will have to have inspectors, but being the hard@ss I am if they can't pass the same test as the welders there isn't a job for them. With all that said it doesn't matter on a cart and in decorative work it is a necessity (and there are codes for decorative ironwork). In non-code work the weld applied meets the needs of the joint. BTW Go1lum you are correct about the root versus throat thing. Root of Weld: The points, as shown in cross-section, at which the back of the weld intersects the base metal surfaces. Throat of Weld = Size of Weld (preferred term): Groove Weld -- The joint penetration (depth of chamfering plus the root penetration when specified). It gets a little more complex for fillet and flange welds but is essentially the same thing. The root is actually broken down into several different parts.Last edited by Jolly Roger; 03-07-2008 at 10:36 PM.Reason: left something outThe difference between art and craft is the quality of the workmanship. I am an artist.
Reply:when we did bend tests in school they always made us grind flat on both sides...  I assume that was just to see cracks easier.I like to party!
Reply:Originally Posted by CaptainWillywhen we did bend tests in school they always made us grind flat on both sides...  I assume that was just to see cracks easier.we have built four lightening land deep hole land rigs.  we have received the go ahead for seven more.  i can tell you that some of the welds will be ground down per the prints.  every floor panel was ground flush on all the outside corners.  every hand rail was polished flush.grinding takes place on many welds to blend starts and finishes when needed.i used to grind most all my welds, but as i have gotten better, i hate grinding a pretty weld.  but then again there are days i want to grind every weld to hide my gorillas.
Reply:Enlpck, your comments are dead right. There are a ton of codes out there and companies write their own now. One of the most strigent is the ASME Code 9- G6 and I had to pass it for years to keep my job. That is exactly the procedure used. It calls for two side bends and two back bends , no flaws allowed. Can't remember the radius of the bends anymore.
Reply:Hello guys,This is my first post so I will try not to upset too many people but some of the answers given have been clearly wrong.I have spent 15 years as an ASME IX coded pipewelder (GTAW/SMAW) and the past 10 years as a CWI.1  Reinforcement does nothing for a weld - If you look in the dictionary you will find the definition of reinforce is to strengthen.2  Never grind a weld - There is no code in the world that says grinding is not allowed. As noted by others certain specifications and applications require the whole reinforcement be removed. The only code I know that deals with grinding is AWS D1.5 (Bridges) that stipulates no grinding allowed at anywhere on the weld test coupon.3  You are NOT allowed to grind a structural weld - When you get into severely stressed structural systems that are subject to dynamic, cyclic or fatigue loading it is not only recommended sometimes it is demanded that every weld is ground and blended.4  The root is the distance from the face to the bottom of the V groove - This is in fact the Throat Thickness.A valid question was " Is it a rule that most reinforcement should not exceed 1/8" ? "Various codes have various limits based on the thickness of the base material. For example ASME B31.3 has 1/8" max for thicknesses from 1/4 to 1/2". The thicker the material the larger the allowable max reinforcement size. If you work on the premise of 1/8" max reinforcement for all your welds you won't go far wrong.Just to finish off, a lot of codes require no reinforcement at all, the only stipulation is it must be above flush.Hope that clarifies some points,Regards,BB
Reply:Welding Web,I put my occupation in my profile as QA/QC Welding Inspector. How did I end up as a Solderer ?Regards,BB
Reply:Your "status" ie, Solderer, is based on the number of posts you have made.
Reply:Thanks Pulser,I have been on the AWS forum for 7 years and I am considered one of the old hands.Feels strange to be a "junior" again,Regards,BB
Reply:Originally Posted by BallbearingHello guys,This is my first post so I will try not to upset too many people but some of the answers given have been clearly wrong.I have spent 15 years as an ASME IX coded pipewelder (GTAW/SMAW) and the past 10 years as a CWI.1  Reinforcement does nothing for a weld - If you look in the dictionary you will find the definition of reinforce is to strengthen.2  Never grind a weld - There is no code in the world that says grinding is not allowed. As noted by others certain specifications and applications require the whole reinforcement be removed. The only code I know that deals with grinding is AWS D1.5 (Bridges) that stipulates no grinding allowed at anywhere on the weld test coupon.3  You are NOT allowed to grind a structural weld - When you get into severely stressed structural systems that are subject to dynamic, cyclic or fatigue loading it is not only recommended sometimes it is demanded that every weld is ground and blended.4  The root is the distance from the face to the bottom of the V groove - This is in fact the Throat Thickness.A valid question was " Is it a rule that most reinforcement should not exceed 1/8" ? "Various codes have various limits based on the thickness of the base material. For example ASME B31.3 has 1/8" max for thicknesses from 1/4 to 1/2". The thicker the material the larger the allowable max reinforcement size. If you work on the premise of 1/8" max reinforcement for all your welds you won't go far wrong.Just to finish off, a lot of codes require no reinforcement at all, the only stipulation is it must be above flush.Hope that clarifies some points,Regards,BB
Reply:Welcome to the board BB, and well said.The difference between art and craft is the quality of the workmanship. I am an artist.
Reply:AWS D17.1 specifically ALLOWS grinding welds.  So does AWS D1.2  So does virtually every weld specification I have ever read (and that's about all of them) allows for welds in butt joints that are designated on the design drawings to be flush "Shall be finished (read ground) so as mot to reduce the base metal by "x amount" or 5% (sometimes 10%) of the thickness, whichever is SMALLER.Im not a weld inspector.  I'm a welding engineer.  I teach inspectors.I r 2 a perfessional
Reply:I don't recall a welding engineer teaching me any thing other than how to make a crappy 6" weld on a test coupon. Beyond that the engineer was lost. No slam at you but I feel that comment was alittle AZZholeish. So big engineer, where did you get this four year engineering degree or were you one of the few elite that went further?AWS Certified Welding Inspector
Reply:Dirty,Yeah, I guess I'm one of those who went further, up the the PhD level.  Paid for my schooling by welding in shipyards, pipelines, construction, and manufacturing.  30 years now.  And I still weld every day.  On production hardware for jet engines.  When inspectors state "You can never grind a weld" with absolute certainty, then they need to be taken down the notch.  Sorry if that seems "azzholeish", but its the truth.  "Never say with abosute certainty that of which you are not absolutely certain"And having indefinite certification to position 6G of section IX of the Boiler Code in GTAW, as well as AMS-STD-1595 in SMAW, FCAW, GTAW, Electron Beam, Laser, as well as D17.1, and many others, I'm sure I could make up for that engineer who made you make a crappy test weld.EnjoyI r 2 a perfessional
Reply:I'm only an inspector but i also teach engineers. ignorant is ignorant no matter how many pieces if paper you have. was the point of that statement to say how good you are or was there another point.
Reply:Assuming engineers can't weld is ignorant.    And as you so succintly put it, ignorant is ignorant.I r 2 a perfessional