welding magnitized pipe

[Piledriver]

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

[T E B]

Wrap our ground cable around it one way if it pull the arc that is right way.

[gizzardgutz]

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!

[bucket]

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.

[10secondtailoff]

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

[Weldtek]

Try DCEP or AC.

[OPUS FERRO]

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

[pinjas]

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.

[Supe]

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.

[Weldtek]

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.

[bucket]

Originally Posted by OPUS FERRO

Open 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

I helped out some well drilling guys and movement or force of put the pipe into the ground causes the pipe to become magnetised. ie. having a north and south pole.
I have had this as well with rolled steel but not to the same degree.

[OZ_Welder]

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

[off-road man]

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.

[ss42768]

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.

[Supe]

Originally Posted by OZ_Welder

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

The zero mag, or variant thereof, is what MPS/Gaussbusters uses. A little 110v unit that gets it's amperage through coiling the leads. It uses a timed, switching, DC power supply that gradually tapers in strength. Sometimes, that's the ONLY way you can get the part demag'd in situ.

[gordon stephenson]

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.

[reverse polarity]

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.

[AndyA]

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.

[reverse polarity]

Originally Posted by AndyA

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.

Is was very strange. We started to drive piling on Nov 5. The longest pieces were 60' driven to about 55' and would weld another usually 30' on to it. We didn't have any problems with magnetism at that time. Then about a month later we were working about 100' away from the previous location and we were driving 70' to about 65' and the magnetic force was strong enough on some pieces to retain a small screw driver placed against the face. One guy had a theory that there may have been some rare earth magnetic stone that the piling was driven through, but I would have my doubts about that happening. Our foreman said that when a piece of steel is hammered on it will become magnetized, but if that were the case, why weren't all the pieces magnetic? All I do know is that trying to weld the magnetized piling with 5/32 rod was almost impossible. The pile driver that started this thread stated that he was having this problem with pipe piling using a chill ring to join the pieces. With "H" piling we had no way to join lengths except for a beveled butt joint and just trying to tack the lengths together to plumb them proved to be quite a challenge.

[MDAWELDING]

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.

[off-road man]

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.

[Pavinsteelman]

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.

[Journeyman 1974]

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.

[docwelder]

that is some fascinating sh!t!! you learn something new every day. i wonder if this magnetic energy could have negative health consequences?

[shortfuse]

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_temperature

Color chart:

http://www.smex.net.au/reference/steelcolours.htm