welding magnitized pipe
Tue, 31 Aug 2021 09:10:57 GMT
I'm on a piledriving job using 5/8 wall pipe with chill ring and 45 degree top bevel. The pipe is magnitized to the point it is almost unweldable.The contractor wants ultrasoundable welds which is proving to be next to impossible.If anyone knows anything that can help please respond
Reply:Wrap our ground cable around it one way if it pull the arc that is right way.
Reply:Welcome to the WWF Piledriver. TEB is correct, wrap the ground cable a minimum of five times around the pipe and strike an arc. If it doesn't stabilize and weld, wrap it the opposite direction. You also swap ends with the piece your adding on, but wrapping is probably quicker & easier. Let us know if it works out for you!Only when the last tree has died and the last river has been poisoned and the last fish has been caught will we realize we cannot eat money. -Cree Indian ProverbSA 200 LincolnVictor Torches
Reply:as per the above post wrap the ground cable and you can use two ground cables one on each side of the joint, weld towards the arc blow and worse case temporary weld a bar across the joint.
Reply:I have just been working on a 12" magnetised line and it was so bad it took 2 of us to pull a large hammer that stuck to it haha but the weld procedure that was in place stated that it was welded on ac nu5 root vodex fill they were all bombed and ultra sound and they all went through wasn't possible to weld on dc
Reply:Try DCEP or AC.Weldtek
Reply:Open Question - What causes the magnetization of pipe. In nearly 40 years of steel-fab the only magnetized section I have encountered was 500 Brinell armor-plate, and we were not welding it. Credit Bucket for mentioning Arc-Blow. In non-mag steel, Arc-Blow most often occurs as a result of a confused ground path. A disrupting electrical field is produced by the random configuration of the elements in the weldment; the result is a disruption of the arc-envelope, thus: problems are immediately evident while welding. Cable wrapping is always the first line of offense. I can only imagine the problems encountered with magnetic material. This problem is not common in other steel shapes. Why is pipe so magnetized: and if this is such a problem, for the sake of weld integrity, why isn't [can't] the pipe be "Demaged" before welding. OPUS
Reply:As suggested, demagnetization is something to consider if possible or a viable option. Something I have imagined is the possibility of using a powerful magnet on the opposite side of the weld on the side that attracts the arc itself. I've never tried it myself, I don't know if it would work, but it is something that I'd consider trying in your situation if you were able to do so. Instead of having the arc pushed away, the arc could be drawn towards a spot. It is only a theory but it could work, in theory, or at least help.Miller 330 a/bp water cooledI believe in gun control, I hold my gun with two hands. If you want to know why, click here.Buy American or bye America.
Reply:Good luck. Sometimes you can try every trick in the book, and it just won't work. I had that issue once when an 80 foot long pressure vessel became magnetized at the inlet (3" thick). 15-20 gauss can give you welding problems, we were at nearly 200 (magnetism was strong enough to hold the filler to the bevel). The only thing that worked was a company called Gaussbusters, aka MPS. They come out, wrap the joint, and use a strong, reversing DC current to drive out the magnetism. I tried traditional methods for two weeks with no success, he was done in 90 seconds. Not cheap, but would have saved money in the long run.
Reply:Welding procedures have been used where magnetic fields were setup to "weave" the puddle in vertical applications. Possible, but not practical. AC, if available, is a great "equalizer" (sort of the COLT Peacemaker of welding). In my experience, weaving has helped in overcoming "arc blow" magnetism.Weldtek
Reply:Originally Posted by OPUS FERROOpen Question - What causes the magnetization of pipe. This problem is not common in other steel shapes. Why is pipe so magnetized: and if this is such a problem, for the sake of weld integrity, why isn't [can't] the pipe be "Demaged" before welding. OPUS
Reply:Hey mate, only just found this thread so the jobs probably done and dusted.....Anyway i have just finished a job in the reduction lines of an aluminium smelter and basically the area is one big magnetic field and some times is near on impossable to get weld down at all. But anyway to cut a long story short these are a few things we did in order to get the welding done firstly we were using an AC pulse welder with verticor 3xp wire, then we used a machine called a zero mag from these guys //www.diverse-technologies.net/ they are not cheap either, i was told they cost around $80k. there was few other little tricks we used aswell, like it was mentionend above about wrapping your earth lead around the joint quite a few times to tray a create a another field, that worked well. another thing we did was use a cellulose rod to to do the root run and the once the gap was bridged it welded alot better. Another thing i heard while i was there was to tack weld two big blocks of solid steel either side of the joint i'm not sure how thing goea as i didnt try it.Cheers
Reply:I work for a large pipeline company here in Canada and we face this problem with some of our existing lines when doing tie-ins etc. They become very magnetic for some reason; some say due to running the live pigs or the cathodic protection. Using a gausse meter to monitor we use a spare welding machine and wrap the pipe many times with the ground cable. Set the machine on its lowest setting and hook the stinger to the ground using a file or heavy piece of steel, then start turning the amperage up with the remote until the gausse meter reads a usable number.You may have to reverse the direction of the wraps if the first way doesn't work. This usually takes care of it.
Reply:We see quite a bit of this at the LWS I work at, as a lot of farmers will buy oil sucker rod to make fences with, they usually end up wrapping a steel clip around the sucker rod, and welding the clip to the rod (versus welding the rod to itself) Lots of guys claim success running 6013 rod on AC, granted this is just for fencing, and not the same as your application.
Reply:Originally Posted by OZ_WelderHey mate, only just found this thread so the jobs probably done and dusted.....Anyway i have just finished a job in the reduction lines of an aluminium smelter and basically the area is one big magnetic field and some times is near on impossable to get weld down at all. But anyway to cut a long story short these are a few things we did in order to get the welding done firstly we were using an AC pulse welder with verticor 3xp wire, then we used a machine called a zero mag from these guys //www.diverse-technologies.net/ they are not cheap either, i was told they cost around $80k. there was few other little tricks we used aswell, like it was mentionend above about wrapping your earth lead around the joint quite a few times to tray a create a another field, that worked well. another thing we did was use a cellulose rod to to do the root run and the once the gap was bridged it welded alot better. Another thing i heard while i was there was to tack weld two big blocks of solid steel either side of the joint i'm not sure how thing goea as i didnt try it.Cheers
Reply:Just on a different track but same subject, we had this magnetism problem on the main coupling between a big GE steam turbine and the rotary multi-stage compressor, The Boffins called in a specialist firm that brought a huge 2 phase diesel generator from Scotland (about 400 miles away), they wrapped the coupling and shaft with a few turns of ultra heavy welding cable, started the genny and switched on the current for just a couple of seconds, Job done.Lincoln SP-170 MigHypertherm powermax 45Lorch T220 AC/DC TigButters FM 215 synergic MigKemppi 180 adaptive mig RULES ARE FOR THE OBEDIENCE OF FOOLS AND THE GUIDANCE OF WISE MEN.
Reply:Interesting thread, I too am a welder on a pile driving crew and have run into this same problem, only the magnetism was on 10" "H" piling. We did try wrapping the ground cable around the magnetized piece, which did not work; however we didn't try reversing the wrap. We were using 5/32" 7018 rod. What did seem to work better was to drop down to 1/8". Once a complete root pass was made it seemed that the magnetism was gone. It also seemed that as the weather turned wet and cold the magnetic field got stronger.
Reply:The weather changing the magnetic field sound like maybe you have stray current running though the piece. I wouldn't expect to see this unless you had really long pieces (pipeline or power lines). I also wouldn't expect to see enough current to generate enough magnetic field to cause welding problems.It's probably something else like a new piece of material or a new arrangement that just coincided with the weather change.Dynasty200DX w/coolmate1MM210MM VintageESAB miniarc161ltsLincoln AC225Victor O/A, Smith AW1ACutmaster 81IR 2475N7.5FPRage3Jancy USA1019" SBAEAD-200LE
Reply:Originally Posted by AndyAThe weather changing the magnetic field sound like maybe you have stray current running though the piece. I wouldn't expect to see this unless you had really long pieces (pipeline or power lines). I also wouldn't expect to see enough current to generate enough magnetic field to cause welding problems.It's probably something else like a new piece of material or a new arrangement that just coincided with the weather change.
Reply:I weld screw piles for a living and you can minimize the arc blow and can even use it to your advantage but u can never rid it completly. coiling your ground is bull****... dosent work, start welding pulling clockwise the same direction the pile was installed if you encounter arc blow stop and move to your right 5" and back weld same dir. towards your bead trapping the concentrated magnetic field, then weld with big steps with constant rod manipulation maintaining a normal to long arc. I use 5/32 and acheive a mint 6-7 mil weld in a pass, controling the arc blow actually allows you to create a bigger weld in one pass with 5/32 its great, at first i thought "i quit" tried everything, the min u think u conquered it it flares up again, i mastered it and the key is rod manipulation and large steps... if u try to beat it ull never win u have to work with it not against it.
Reply:Not to cause a arguement but when doing a mainline(20-48")butt weld wrapping the cables from a SPARE welding machine with them hooked together and adjusting the amperage does work,believe me! No BS! When you are making a weld on a high pressure mainline with 100% xray you have to beat this and it does work. We used to just pound lots of wedges in as the more iron touching would some times work but sometimes even after root you can get it again in different passes.
Reply:Had the same problem with a column for the hub tried to fluxcore and subarc plates on the dust from grinding would jump into the weld and fail ut, we had to make new plates and call in the demag guy to fix.
Reply:If you can run a preheat on the pipe with a tiger torch it will demag. As an apprentice I worked with a lot of severely magnetized drill stem. Preheat steel to red heat and it will loose it's magnetic polarity. You can try the cable wrap technique on pipe but not so much on a long flat plate weld. I remember a floor plate on the back of an 85 cu.yard B&E Dragline that was so magnetic we could hang a 12lb sledge hammer from it. We used about 30 big plate magnets spaced a foot apart, staggered and alternating sides to break up the field, down the length of a 40 foot weld. We put in three tapered blocks of weld 18 inches long, took off the magnets,and then put in a preheat with torches for about two hours. It went from impossible to done, in one shift, but we all had half-cooked knees.
Reply:that is some fascinating sh!t!! you learn something new every day. i wonder if this magnetic energy could have negative health consequences?
Reply:Journeyman is on the right track about heating. It may not always be possible to heat the steel, but if you can, you need to heat above the "Curie Point" or "Curie Temperature" to de-magnitize if using heat.The Curie Point is the temperature above which metals will de-magnitize. Steel (iron) for example is 770 deg. C. which is about 1418 deg. F. Check out the Wiki link below:http://en.wikipedia.org/wiki/Curie_temperatureColor chart:http://www.smex.net.au/reference/steelcolours.htmLast edited by shortfuse; 12-15-2012 at 11:29 PM.I don't have a clue about plate or I/H beam that's magnetic since I haven't seen it but...when its drill pipe, use AC and a 6011, discussionver. I've welded tens of thousands of feet of this crap and its by far the best way, the only way. I just finished about 2000 feet of top rail and post, 2 3/8 drill stem (not upset or flow line, drill stem) and you could hang an 1/8th inch rod off the top rail by just touching it to it. I have wrapped pipe with the stinger, wrapped pipe with the ground, peened it with a hammer, stuck magnets to it, dragged steel from one end to the other, prayed, cursed, showed up early and all out quit and swore it couldn't be done. All that works, every time/all the time is a 6011 on AC. You need to turn it up a little and short arc it. Also, keep your ground within about 50ft. You can go crazy, as I have, trying to find out why its magnetic and how magnetic and so on, who cares? AC and 6011 and forget it!!!! Be careful if your welding this around any grass or in wind because the arc blow turns into spatter blow. You will be shooting sparks for 6 feet in all direstions so plan ahead and breathe through your nose and pay attention to the smells . Hope this helps.Last edited by colddeadhand; 01-11-2013 at 08:40 PM.
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