Starting and stopping welds - YorkiePap?

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This is a topic I don't remember seeing. I thought YorkiePap might have some insight, but anyone else is welcome to comment.I know that starting and stopping a weld is not a good idea, especially with pipe or pressure welding. And I'm sure practice, practice, practice is the best advice. But I don't get to weld everyday and most of my welding is short runs on home shop projects. Usually it is because I can't see exactly where I am - at the end or off the line. So my question is not whether it is good or bad, because I already know it is bad technique. But when is it OK vs. unacceptable? What should you do when it happens - start back immediately or let it cool first, back up over the stopping point, grind out the first weld, don't worry about it?       Burt _____________________Miller Syncrowave 250Millermatic 211Miller 375 Plasma Cutter Hobart Handler 12010FtDrillBit.com
Reply:Hey Burt,First, you need to give more information regarding you applications, process you are using, & the extent of your welding/repairs/job/equipment you have. If you are doing work at home with repairs & projects, you need not be concerned with any starting or stopping. That will not have a major effect on your quality or strength of weld. Most home/hobby weldors do not have their repairs or projects inspected, X-ray'd, dye tested, or UT scanned.Ok, if you are using SMAW, when you stop, just chip the slag & wire brush the end of the weld to bare clean metal again, strike your arc just ahead of the end of the previous weld & push back into the weld & continue thru that rod. Do the same with each succeding rod. With MIG, solid wire/gas, I just wire brush the end of the bead, be sure to cut the wire prior to each start, start your arc just ahead of the end of the bead, & again, flow into the previous weld & continue. With flux-core, chip the slag/wire brush or wire wheel, & be sure to have a fresh cut on the wire, & repeat as you would with solid wire. These interruptions aren't a real concern, as you have to interrupt with SMAW for a new rod. With MIG, most generally will vary a bit off the joint if their vision is not clear & illuminated from the arc. Personally, I like the AD helmets because of better vision of the puddle & travel.You will find that those in the pipe, structural, & pressure vessel welding will follow a set WPS as to parameters required when starting/stopping. For those of us doing general repairs/projects, starting & stopping will have no major effect if your welds are good, solid penetrating welds that are tied in correctly. You can always test a few samples of starting/stopping with a 10lb sledge to view any discontinuities. Hope this may help you understand these effects. Post some pics of your results. I'm sure others can offer additional suggestions.DennyComplete Welding/Machine/Fab. ShopMobile UnitFinally retired*Moderator*"A man's word is his honor...without honor there is nothing.""Words are like bullets.... Once they leave your muzzle, you cannot get them back."
Reply:Re-starts (starting at the end of a previous weld) are a common thing, especially with stick welding, as you can only weld so far with one stick.  First be sure the end of the weld is clean of slag.  Start at the end of the crater and do a small quick circle back to the middle of the crater to fill it and move on.  If you create a lump at the re-start, you can grind it flat before putting in another pass over top of it, if you're doing multiple passes to fill the joint.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:Often it's imposible to run a bead nonstop. As said with stick, you can only go so far with one rod. In other applications it may be because you are trying to keep the heat down to prevent warping and so on, so you need to move around to keep the heat down. There may be an obstacle that prevents you from making a continuous bead, or you may simply have to move to continue such as if you are doing a long bead.The trick is to learn how to do the restarts correctly. frequently the issue is either with slag getting trapped or other contaminants at the start/stop point, or starting too cold. Cleaning up the start/stop well with the chipping hammer/brush or with a grinder will take care of a lot of the slag issues if you are laying a good weld to start with. As said how you tie in to the previous weld can help eliminate cold starts. Practice, practice, practice... .No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Thanks, Denny, DesertRider, and DSW (the 3 D's!).As stated, I'm not welding pressure vessels or anything that would ever get xrayd!Most of my projects I use MIG, occasionally stick. So it sounds like I may be more concerned than I need to be as long as I tie the new weld back into the old.Denny, you said to always cut the wire before starting again. That is new to me. I'm curious why that is necessary? Of course I do to adjust the stick-out if needed. Is that to eliminate contaminates from the burnt wire? I will have to develop that habit - I don't remember reading that anywhere. That's the kind of advice I'm always looking for when I read the forums. Anything to improve my technique.Thanks again, I'm sure we may attract some other posts.Last edited by wb4rt; 06-04-2010 at 12:20 PM.Burt _____________________Miller Syncrowave 250Millermatic 211Miller 375 Plasma Cutter Hobart Handler 12010FtDrillBit.com
Reply:I dont know where you got the impression that its frowned upon to have starts and stops on pressure vessel work but you were mislead.  As long as they are properly preformed, they should have no effect on the finished product.Have we all gone mad?