Ongoing debate over finished product!

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Ok, here is the question at hand. Once welded regardless of intended use can a person use a flap wheel or sanding wheel to remove and blend the excess weld protruding from the joint without loosing any structural properties?This would seem to have the shop I work in devided. Half of the guys say yes it is just a protrusion and has no bearing and is strictly a cosmetic choice. While the other half says it must remain to keep the strength.I know when I use to build trailers and ornamental gates we always sanded down outside edges for appearance and safety. I figured that there is such a vast knowledge here that I would get my answer finally. Or could it be that everyone here shall be divided as well.Building mudtanks and other oilfield equipment day by grueling day.---------------------------------------------------Victor preformerMillermatic 251Miller Thunderbolt 225Too many grinders and the likeGone but not forgotten Miller Bobcat 250Comming soon Lincoln Ranger 250
Reply:to much weld is bad it put's stress on the joint to little and it make's it weeki know thats not much help .i guess it depends on what your weld is holdingChuckASME Pressure Vessel welder
Reply:An ironworker friend told me yrs ago that any exposed vertical welds inside a bldg. are welded uphill w/ 7018 until a little above the surface,then one more pass is made downhill and hot to make it flush w/ surface. maybe this has changed,I don't know.If this is still so,I would think making the weld on a structural support beam flush wouldn't weaken it. We'll see how many different opinions we have here.                                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:A good weld ground flush will be stronger than the parent material. Thats my story and I'm sticken' to it
Reply:Originally Posted by TEKA good weld ground flush will be stronger than the parent material. Thats my story and I'm sticken' to it
Reply:I've always ground my stuff flush with no problem.DewayneDixieland WeldingMM350PLincoln 100Some torchesOther misc. tools
Reply:As said, the excess reinforcement can provide a stress riser, increasing the risk of failure.A full penetration weld should be flushed down (or blended smoothly if not a butt weld) to eliminate the stress riser.If the weld is NOT full penetration, the excess reinforcement may make the weld stronger, if the reduction is strength due to the stress riser is less significant than the reduction in weld section from grinding it off. If there is a sharp groove at the edge of the weld, it should be blended to a smooth curve if possible, and this will reduce the stress riser.
Reply:so far it would seem that I was on the right track, we get alot of people in my shop who for one reason or another can have a good day and pass a weld test but hardly know anything. I shall direct those in doubt to this thread.Building mudtanks and other oilfield equipment day by grueling day.---------------------------------------------------Victor preformerMillermatic 251Miller Thunderbolt 225Too many grinders and the likeGone but not forgotten Miller Bobcat 250Comming soon Lincoln Ranger 250
Reply:i go by the "if you dont have to grind it...dontrule..."welds shall not be ground down"..N.H.R.A. rulebook......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:The way I see it...ground and flushed welds are the mark of a consciousentious welder, unless it's expressely prohibited by a code or rule. I care about how my work looks. I find people who employ me as a hobby welder, like the way 'finished" joints look, as do I.When I make stuff I like to finish the welds simply because it's smoother under paint and I think it looks better. I don't weld things directly involving the safety and life of another person, i.e pressure vessels, car ramps, harness / hangers, tree stands, etc. If my smoothed joint breaks, no one gets hurt and I can repair it, learning from my mistake and making it stronger the next time. Bottom line...if you like to smooth it do it.Ronnie
Reply:Originally Posted by ronnielyonsThe way I see it...ground and flushed welds are the mark of a consciousentious welder, unless it's expressely prohibited by a code or rule.
Reply:We all know that some work requires grinding such as cosmetic work on autos, places that need clearance, etc.I agree with Engloid, Grinding is fine, but if it's a good looking quality weld why grind it? It's a waste of time and money as far as I'm concerned. When I see a weld that has been ground I usually wonder why they felt they had to grind it. You know was it poor or just ugly? Washman
Reply:Well not all of us are welding super stars and we may very well grind our welds down because they are poor and/or ugly. A lot of my work is ugly, so I grind. Or it just might be because I want a flush finish too. Ya never know. In any event it seems there are times when grinding a weld bead flush is preferable to not grinding, just as it holds true for the opposite. Not as simple as always grind vs never grind. This is an interesting read from one of the other boards.http://www.hobartwelders.com/mboard/...ad.php?t=13253Last edited by Sandy; 11-24-2006 at 01:03 AM.
Reply:certain CSA codes prohibit the top reinforcement from being removed, It really depends on the type of joint. I will grind welds flush as long as there are other full welds still hold it (such as the outsides of a 90* joint)in my experience a fully penetrated joint that is ground flush can fail.I had one such fail on me recently. Since the overall component did not lend me freedom to change the design of the joint, I had to re weld the joint. This time I left the top reinforcement on and it has so far doubled it's previous life span.
Reply:The NHRA prohibits grinding because many home-built racecars are welded by non-weldors with undersize or improper equipment and/or materials. They want to see the real weld for what it is during inspection.If you get somebody using a 110 MIG with .023 wire on 1/4" material and grind the unpenetrated weld smooth, it will look fine but have no strength.
Reply:I don't see what what difference it would make if you don't disturb the root of the weld.
Reply:My 2 cents is that it depends on the individual weld and it's application. A partial penetration fillet that carries a load would definitely not benefit by being ground flush, for instance. If left unground a flat butt weld that is subject to flexing could crack due to the excess bead acting as a stress riser, as enlpck pointed out. As Engloid stated, a coupon being sent for testing has to be ground flush, and in the right direction to boot. Bend a coupon with grinder marks travelling perpendicular to the direction of the bend and you are asking for a fail. The grind marks have to be the same direction as the direction the bend will be made. If you are only concerned with a decent joint and the look of the finished product, the decision to grind is up to the individual. I've seen some real pretty beads I wouldn't think of putting a grinder to, and made a few I covered over 'till I could find the grinder!You have my pennies...Last edited by Clanweld; 11-27-2006 at 10:48 AM.If you don't have the time to do it right, then you definitely don't have the time to do it over.
Reply:Interesting discussion.  So far it would appear yall are discussing steel.  Would the answer(s) be the same for aluminum?  Inquiring minds want to know.  I know I'd like to grind off an ugly weld but have been reluctant to remove anything that might furnish additional strength.Thanks,Clay
Reply:Generally, if the design is good, and the stresses are well within safe limits, and there isn't severe load cycling or vibration, grinding is primarily needed for purposes of appearance or fit (when a proud weld prevents a part from fitting) and most welds are left as welded.When there is heavy cycling of load, relatively low factor of safety, high corrosion succeptability, etc, grinding is common. No matter what the material. In some cases, just to reduce corrosion, polishing will be done-- every pit or groove forms a concentration point for an electrochemical cell. Had to repair a set of joint bars for a compromise joint (two different size rails meet) that had cracked over the weekend. Originals had sharp corners to make the offset, and the corners nucleated cracks. Did the weld full pen with 7018, beveled both sides and background, adding a fillet at the inside corners to allow for a smoth transition. The surfaces were then ground flat, and the fillets were ground to a nice happy radius. No sharps. Smooth. No stress risers. Literally an hour after the bars were reinstalled, a rail snapped a few feet from the joint (this had to do with why the work was being done... rotted ties and swampy ground make for problems). Bent the repaired bars at an angle of about 10 degrees. Not a crack. Prior to the repair, the bars had never been bent, et they cracked out right from the stress riser.  Moved the locomotive off the broken section (just under 20T per axle), straightened the mess up with a jack, put splice bars on th break, and ran right back over it. The bent bars--no problem. The rail, coincidentally enough, broke where a chip about 1/4" across, had been knocked off the foot of the rail. Call it about 1 to 2% of the cross section of the rail removed. The chip had been there for many, many years, as evidence by the rust on faced where the chip came out. As a side note, things could probably be left as they are and be fine for years, but the rail that broke will be replaced anyway.