Scharrer,
The one thing I want to stress is using the key hole oscillation method typically does not bring under cutting in the 2G , 4G or the 3G up-hill positions. Dragging the electrode with out any oscillation typically is what causes that in my experience. Down hill welding by using the dragging technique is best. If you are getting undercut in that position using that method it could be arc blow, excessive high-low on the fit-up or a grounding issue. Of course this is my opinion based on my experience and as a welding instructor for 8 years with FD.

I have experienced extreme toenailing with 6010 occasionally and sometimes it was the result of arc blow more than anything. Another factor that can make it occur more often in a narrow groove angle or groove faces being rounded.

If the joint fitup can take the added amperage you can almost NEVER go wrong with turning it up.

Have a great day.

Some good info here. It sounds like when the gun is lifting the stud it is not plunging the stud back into the molten pool creating arc blow. Your settings look good although amps could be around 550, but don't think thats your issue. It could be a problem with your gun.

https://www.imageindustries.com/wp-content/uploads/2014/07/arc_welders_guide.pdf

I agree. A picture would be very helpful. Like John, I’ve shot thousands of studs over the years, but I’ve never heard of arc blow on a stud weld. Another thing I sometimes to to help make sure the weld goes all the way around the stud, is to increase the arc time, which, once the trigger is pulled,  Gives the weld a little more time to complete the circle.

Scott,

Interesting.  I have generally seen this when the studs were either tilted too much or there was extra mill scale on one edge that didn't allow for complete flash or at least uneven flash.  Had never heard it referred to as arc blow though. 

Their solutions make a bit of sense.  It would depend upon the reduction in the flash if it was rejectable and thus require correction.  Just because a flash is small does not reject the attachment.  It must be non-existent or have undercut into the stud to make it rejectable.  That or come off with a blow from a hammer. 

John's remedy makes sense as well.  If it happens too often, up the amps and see if it just wasn't melting off quite enough.  Though his suggestion seemed a bit high to me. 

Hard to tell since we have not actually seen the OP's pic of the situation. 

Have a Great Day,  Brent

Brent, I wasn’t sure how arc blow applied to stud welding, so I just attached a link. If the post is referring to a lack of a 360 degree flash, I’ve always just adjusted the ferrule grip, because my experience is that the ferrule is simply not centered on the stud when the trigger is pulled, causing an uneven or unwelded section at the stud base.

Brent,
I've shot and have seen tens of 1000's of studs shot and have not experienced arc blow either. I was also thinking that what he was seeing was the flash around the base wasn't perfect and maybe the machine needed a few more amps to get a 360 degree flash.

This is interesting.  I was waiting for others to chime in but John and Scott didn't go where I was hoping. 

I have never experienced "arc blow" on studs.  I have shot and inspected literally thousands of studs and this is new to me. 

To make sure we are actually talking about the same thing, can you please further describe said "arc blow"?  And, if at all possible, a picture would really be helpful here. 

The flash around a shot stud does not have to be a perfect ring with no 'defects'.  If you are looking at some splatter and/or porosity in the flash you do not have a problem.  Have you checked to make sure you still can bend test them without any failures? 

Have a Great Day,  Brent

Just for kicks turn the machine up to 620a @ 0.33s and see if that helps with your stud welds on 3/8" diameter studs. My welding procedure has the amperage range from 620 to 830 for a 3/8" stud. May not help with arc blow but you may get acceptable results at the stud base.

This link may be helpful....

https://www.sinostoneltd.com/how-to-prevent-magnetic-arc-blow.html

When checking our lift on stud gun, we have noticed when the trigger is pressed and lifts the stud, it does so in a way that is not straight back, it kind of goes towards the top when pulled back.  I'm questioning this because we have been experiencing arc blow on 3/8" studs.  Machine settings (525amps, and 0.33s) any information would be helpful. 

Thanks.

Slag trap is strange indeed.

Assuming you have clean cut edges with no cutting dross, no cutting fluid/oil.

Arc blow is the first culprit to look for in my opinion... And yes you can have Arc-blow with AC.    
*  Perfect work lead connections
*  Weld toward the work clamp... If that does not work, weld away from the work clamp.. If that does not work split the work lead to both ends.

Flux recycling...  Even fresh bagged flux..  If you are vacuuming and reusing will lose it's chewy goodness after a few cycles... Meaning that when your drum gets half empty, refill with fresh to keep the flux in optimal condition.. If it goes from grainy to powdery, you have waited too long.    Empty everything and start 100% fresh every 5 days-ish

A loose work connection with powdery flux is the perfect storm for Arc/Blow & porosity.

Tandem power supplies and tandem electrodes,  or "Tiny Twin"  side by side wires with one power supply ?

I'm still thinking Arc Blow...….. But say more about the porosity and slag..

Is it very fine centerline porosity?  Big holes evenly spaced...  What are you finding with the slag when you gouge..  What does it look like. ??

We've been talking about protecting the eyes from the arc, but what about the lungs?

If I had to earn a living burning wire once again, I think I would spring the money to purchase a helmet that also supplied fresh filtered air for a couple of reasons. The first being that filtered air protects the lungs. I can't recount how many doctors have told me I need to stop smoking. I've never smoked in my life, but a lifetime of breathing fumes seems to have a similar affect. The second point would be the cool air blowing across the face beats sweat running into your eyes any day.

Al

Here are a couple of things to think about.

Was the backing strip absolutely tight/flush?  even a small gap can blow a test.   Clamps while tacking can solve that one.

98/2  Argon/Oxygen gives a nice spray transfer arc with GMAW and (I'm assuming) .035  ER70S-6 solid wire.  You can see that needle sharp end of the electrode wire and the bell shaped arc very clearly.

Having said that, the Ar/Oxy mixes also spray a lower voltage than Ar/Co2 mixes and this can cause some confusion and difficulty.  Let me explain a bit more.

To get that root fusion on each bevel edge you need to do one of two things... 

1 make a root opening tight enough to get good fusion in a single pass.  or
2  Make a root opening wide enough to accommodate a split root.

Either way:  With Argon/Oxygen mixes and weld test assemblies, in my opinion, it is critical to use the LOWEST ARC VOLTAGE VALUE possible and still have a good spray transfer. 

Why is that important Lar?   I'm so glad you asked!    As the voltage increases, the arc length increases, and so does the width of the bell shaped arc.  The arc spreads out the heat and can bridge the fusion along the root/toe of your test assembly and cause defects exactly like the ones we are seeing here.    Furthermore:  You may notice that when you prepare your test assemblies to ground *brite metal* that the arc length is longer and the arc sound is quieter than you normally experience when welding over typical steel with some mill scale....... 

So what do I do about all that Lar?    Easy stuff....  Grind some steel to brite metal and make a weld.  Set your WFS to get about 230 amps and start about 26 volts.  Look at the arc length.  If it is 1/8" or more, reduce volts by 1/2 volt increments until you see spatter, then increase 1/2 volt and try again.   Don't mind a little crackle sound.  As long as there is no spatter you want to keep the arc as short as you can get it.

Don't whip!   Don't weave !   Just a straight root pass that goes in like caulking.

A row of dimes is for E6010  not GMAW!   Never whip spray GMAW

For the split root focus that short arc on each beveled edge without touching the other.  You should be able to literally see the fusion happening.  The root pass should be rather small. No larger in volume than a 5/16" fillet, and probably closer to 1/4.

If a single pass root, both bevel edges must be equally fused, which means they must be close enough together to do it.  I like a 3/16" root opening for this.

Also:   I know this is more than you asked for....   .045 is a much more efficient electrode wire for spray GMAW.  It will carry more current and produce a bit wider puddle at the root in flat and horizontal position that is a bit more controllable than you can get with .035 at a similar amperage.......... 

Frankly if I were in the flat position, I would want to run that test assembly at nothing less than 250 amps.  But you may be bound by a WPS that does not allow for that.

Vertical uphill progression using 1/8-inch diameter E7028:

Most welders try to use the lower end of the amperage range and fight the arc all the way. Turn up the amperage to around 135. Keep a short arc. Weaving is fine unless the WPS is qualified for CVN and the heat input is limited. When weaving, hold the corners to permit the weld to fill and avoid undercutting the edges.

When you set up the plate assembly, tack weld the bottom and the top of the plates to avoid magnetic arc blow as you approach the uppermost two inches. "Grounding" the test plates both top and bottom reduces the current through each tack and reduces the magnitude of the magnetic field that causes the arc blow. Position the plate assembly between your belt buckle and sternum. You are less likely to roll your wrist and change the rod angle, which by the way, should be about 15 degree upward.

Good luck and practice, practice, practice.

Merry Christmas - Al

Brian,
  As has been stated, D1.1 does not specifically prohibit grinding on the cover pass. Personally I believe it is a mistake for companies to allow t other than on start and stops and other issues like have been described ("gas runs out, some arc blow, whatever").

I have seen this have bad results for several companies in the past. The worst was at the last company I worked for. Their weld test guidelines stated in big, bold red letters "NO GRINDING ON COVER PASS, 1/8" MAX REINFORCEMENT". however other inspectors were allowing it. there were cover passes that had up to and sometimes over 1/4" reinforcement that were being ground down to 1/8'. I would not allow it per the company test guidelines. They then reworded it to allow grinding on the starts and stops. I told them this would not solve the issue I was witnessing.

Now comes the kicker and the comical part to this whole thing that was going on all at the same time.

The field welding foremen and super's were constantly complaining and wanting to know why the welders that they were sent could pass the weld test but could not perform out in the field!! Also there was a TPI that was rejecting welds left and right in the field and he had witnessed several of the weld tests on the people he was rejecting welds from. He told them the same thing. "Your test is yours, these welds are mine and the customers and will meet the code requirements and the specifications set out by the customer."

Well you have given them a test in perfect conditions on the easiest weld they will ever do here, with the easiest criteria. Then you do not hold them to that criteria and wonder why they can not perform under harder conditions.

Again, I have seen this at several different companies. If that is the way they have written their test guidelines then that is their problem as long as you have followed what they want done.

I personally think allowing the entire cover pass to be ground down to 1/8" it ignorant and any company that allows it deserves every bit of problems and headaches that result from it.

jrw159

Hello everyone, I would like to get the opinion of some folks in this group if possible.

I'm a cwi and I work for a AWS ATF. We're currently in the process of making some changes and one thing that we are butting heads on is the issue of grinding on a certification test.

I realize things happen sometimes during a test, and that some grinding is in order occasionally. The gas runs out, some arc blow, whatever. But I am seeking your opinions on the cover pass of the weld.

It's my opinion (and that's all it can be because the folks at aws don't have the stones to answer this for me) that if you exceed the allowed groove weld reinforcement then you are done. But someone who is also working here says it's fine to grind down any areas that exceed the allowance on weld reinforcement. So if you have a cover pass that's 3/16" high, you can grind it down to the 1/8" max and still pass the test.

It's not addressed in d1. 1. It should be. And aws won't give you an answer on it. So what do you folks think? If I had someone do that on a weld test at the shop I used to work at they'd never get a phone call. I don't believe that people should be trained to believe that it's OK to take a welding test, and grind down what doesn't conform to the specs because that's what they'd do on the job.

Am I being too picky by wanting to see welds that aren't ground down on the cover pass?

Brent, blowing through all of this was the crux of the problem. You are exactly right, slowing down to take time to read through it better instead of trying to correct an out of control situation on the fly.

My plan was to run the gamut of tests using all of the available SMAW rods and thicknesses for galv'd coatings so we could cover any future situation regarding welding galv'd decking but then they show up in a a couple hours late in mad rush with only 7018 and 18ga galv'd decking on the truck. I quickly read past the arc spot statements in the essential variables for both the WPS and Welder performance and saw the statement regarding using 18 ga to qualify for 16 ga and thinner and incorrectly thought that the D1.3 committee had given us more leeway when qualifying. I should have known better

Hi All, have a Ranger 8 with a command 20 on it. It runs pretty good and starts easy, but is for sure blowing oil out the right bank when looking at the engine. I'm also having trouble getting the engine to idle up to work speed automatically when striking an arc, wonder if anyone has any ideas. Thanks in advance for any help.

Porosity can be caused by several factors.
A simple breeze can blow away the shielding gas.
Too little gas flow which does not provide enough shielding of the atmosphere from the molten weld puddle.
Too much gas flow which results in a venturi effect that will actually draw atmosphere in and contaminate the weld pool.
If the base material is not clean, the contaminants will boil out in the weld puddle.
If the filler materials are not clean or have absorbed moisture those can cause porosity.
If the base material is colder than the dew point, moisture can form on the surface.
In correct technique maintaining too long of an arc can let atmosphere be drawn in.
Welding in a corner can cause a ventri effect.
Excessive voltage can sometimes cause porosity.
Removing the Tig torch too quickly from the weld puddle after extinguishing the arc or too short of a post flow setting can cause porosity.

I'm sure others here can chime in with other factors that escapes my mind at the moment that can cause porosity, but without more information about the welding situation, it is difficult to come to any conclusion or offer any advise.

Hello Tom;

One must consider that D1.1 is intended for carbon steels or high strength low alloy steels joined to the same. Likewise, D1.6 is intended for stainless to stainless. Dissimilar base metal combinations, they are a tiger of a different stripe.

ASME has a different philosophy from AWS. Whereas AWS codes typically endorse the concept of prequalification, ASME has the philosophy of "show me it will work."

ASME operates under the presumption the person making the decisions is knowledgeable and familiar with the technology and processes they are using. AWS, not so much.

The A number is an additional constraint that comes into play when welding similar base metals, but involved additional complications when dissimilar metals.

Not only do you see A numbers in ASME, but you used to see the weld deposit chemistry as an essential variable in the old MIL-STD-8604 for welding aluminum alloys. The reason was due to the exact factors you mentioned.

AWS B2.1 used to have different F numbers for all the ferrous filler metals differentiated by the welding processes. It wasn’t until AWS tried to harmonize B2.1 with ASME Section IX that the multitude of ferrous F numbers were combined into the F6 grouping. That was a mistake from my point of view.

It has been my longstanding view that ASME is one of the few codes that allow the unwary to write a code compliant WPS that simply will not work. In that respect, I believe the AWS structural codes are more relevant and more conducive to developing a “workable” document the welder can actually implement.

I always write a WPS with the welder in mind, something ASME seems ignores. That shouldn’t surprise anyone familiar with welding, few of the people on ASME’s committees have ever struck an arc. An engineer’s perspective on welding is different from a welder’s perspective. The engineer is interested in the mechanical properties and whether the weld will perform as expected. They expect the welder to be trained, skilled, and knowledgeable. Those attributes that are skill related are not usually addressed by the ASME WPS in sufficient detail. Why, because many of the engineer tasked writing the WPS are clueless about those aspects of welding. Actually, I see AWS structural welding codes drifting in that direction as well.

All that being said, I find the A number, if properly used, a valuable means of ensuring the wrong filler metal isn’t substituted for the production weld. And for many of the reasons you’ve noted, the person tasked with writing or implementing the WPS must know when a chemical analysis of the deposited weld metal is more relevant than the chemistry provided by the manufacturer.

In reality, some of the element you mentioned, i.e., silicon, does affect the mechanical properties. Silicon and manganese are effective deoxidizers and are added to filler metals for that reason as well as others. With a change in shielding gas, i.e., CO2 to ArCO2 for example, those elements are not utilized as deoxidizers and they become alloying constituents. As such, the tensile strength and yield strength goes up at the expense of ductility. The change in weld deposit chemistry may result. Am I going to blindly use the A number provided by the manufacturer that qualified the filler metal using CO2  or as the engineer in charge consider the chemistry of the deposited weld metal?

One must also consider the fact that ASME Section IX also considers the shielding gas to be an essential variable. A change for one gas to another is something that must be considered and usually requires a supporting PQR to demonstrate the resulting weld will still provide the properties required. 

Section IX considers the groove detail to be a nonessential variable. However, when welding dissimilar base metal combinations, the amount of dilution can change the deposit chemistry. So, should one blindly use the A number determined by the manufacturer when qualifying the filler metal on matching base metals, or base the A number on the actual deposited weld metal chemistry? Where should the sample be taken; from the center of a multipass groove weld, from the weld interface, if the weld interface, which one? Things can get pretty complicated very quickly. The point really is whether the groove detail has an affect on the deposited weld chemistry. I believe you and I agree that it does if the amount of dilution is substantially different based on thickness, and groove detail. That’s really when the A number shines. If the dilution substantially affects the resulting chemistry of the deposited weld metal, a change in A number results and a new supporting PQR is in order.

Much of this is beyond the purvey of many CWIs, so while a CWI may be able to write a simple prequalified WPS, additional education and training may be warranted for someone tasked with developing WPSs for combinations of dissimilar metals. 

Just my ramblings and my opinion on the subject. I expect there will be blowback from some that work with ASME Section IX, but this is how I view the requirements of A number. Simply put, it attempts to prevent the mindless substitution of filler metals simply because they are from the same F number group. Consider that an ER70S-3 belongs to the same F group as ER309. Just because they are from the same F number grouping, we can agree that the chemistry, thus A numbers are going to be different. It is the A number that keeps us from substituting ER70S-2 in place of ER309 when welding carbon steel to stainless steel.

What about substituting ER308 in place of ER309 in the case of a single pass weld joint 1/8-inch carbon steel to austenitic stainless steel? Would the A number be affected?

Let’s assume the Cr and Ni are reduced by dilution so that only 60% of the Cr and Ni are contained by the fully mixed deposit, that’s an assumption, but reasonable for a square groove with no root opening.   The ER308 has roughly 19% Cr and 9% Ni. The ER309 has roughly 23% Cr and 13.5% Ni. Both filler metals are grouped as being A-8. The chemistry of the weld deposit is going to be roughly 10% Cr and 6 Ni using ER308. The chemistry of the deposited weld is roughly 13% Cr and 7% Ni using ER309. The resulting weld deposit chemistries are sufficiently different that the A numbers would be different, Thus if the WPS was qualified using ER309, one could not substitute ER308 and expect the same A number. One would have to qualify a new WPS before making the substitution. If one blindly uses the A number derived by the manufacturer, the results would not be so favorable. This conclusion is bourn out if a solution is derived using the WRC diagram or the WRC diagram as modified by Kotecki and Liphold. The metallurgy of the deposited weld would not have the necessary Ferrite and the morphology would be unfavorable if one was to use the ER308 filler metal in place of the ER309.

Best regards - Al

Hello, Al!
So, we finalized the issue, only 60% of test specimens are acceptable --> no reproduceable success. Also our material engineering dept. says: "Ni-alloy steel welding of LNG tanks that GMAW / FCAW have the risk of poor sidewall fusion. There are several recommendations on GMAW like which arc types to use - spray arc, short circuiting arc or pulsed arc - depending on targeted effect like weld deposit rate, weld position, distortion, etc. In addition to the generally known issues with side wall fusion when using GMAW / FCAW, one significant problem that is frequently encountered with the nickel steels is that of residual magnetism causing arc blow".
Therefore, we've excluded GMAW/FCAW and switched to SMAW/SAW.

http://www.twi-global.com/technical-knowledge/job-knowledge/welding-of-ferritic-cryogenic-steels-100/
http://www.ozmetalsan.com/images/catalog/72595ESAB_LNG_Tanklarinin_Kaynagi_-_EN.pdf

Thanks for your support.

Any ferromagnetic material can be magnetized and yes, suffer the effects of arc blow. The higher the amperage, the greater the problem.

Al

I know the Skills USA folks us AC for their E7018 open root pipe and plate welds.

I know AC will often mitigate arc blow.

But I would think AC might also create a "softer" arc with slightly less in the way of a penetration profile...  This would be a benefit on lighter material where burn-thru is an issue... It might work the opposite for thicker material or procedures that demand a very specific perpetration profile that was attained with DCEP.

I still have an old AC only Lincoln tombstone buzz box in my garage that I at one time used with special 7018AC electrodes... Now it just sits, dormant, silent,, waiting for an opportune moment.

No harm no foul! I'd rather be called a dumb ass by people who are trying to help me, than have a foreman call me a dumb ass. Lol

I bet you I need to turn up my power! I've been running the root at 87 amps, and my hot pass at 100-102 amps. I always ran low amps because when I first started 3G I would long arc, and either have severe arc blow, or I would completely blow through. I don't struggle so much with long arcing anymore so I reckon I should crank it up some! Thank you!

1st, try to eliminate/reduce spatter through electrode angle, lower amperage and management of magnetic arc blow.
2nd trick is to use a scraper or chisel.
3rd is to be mindful of direction of rotation when using these tools.
4th, 10K rpm is going to have some "kick back" under certain articulations and weldment geometry. Glove up, leather up and learn to handle these tools with authority.
I have one at home and they are very good grinders.

I know this comment is late but in case you havnt figured out how to fix your arc blow problem;trying moving your ground to the opposite side of your work piece from which it was when the arc blow occured.

As someone who got thrusted into a Quality Control lead position which subsequently meant I had a need to start studying everything let alone for the CWI test, this board has been an essential tool for me. There's  been numerous times I've searched something and the question has already been asked. I can only speak for myself, but it would be a huge blow to lose the information here.

Hey Kevin,

Glad to hear you are getting some easier welds...  In my opinion there is a silver lining to your cloud of arc-blow :)    Meaning that It will come back and your students will be forced to deal with it, thereby learning important things for the trade.

The dead short technique worked well enough for us when things were really bad... But never lasted very long.   

So we kept a 50 lb. box of E6011 electrodes on hand at all times....  When we begin to experience arc-blow we break out the 6011 and make a series of AC welds, moving the work lead to various points in the welding fixture.  This way the AC current flows through all parts of the fixture and has a good effect at breaking up magnetism when it's not too severe.

That is a somewhat tight gap/groove angle for manipulating the electrode in however electrode storage conditions and electrical factors can increase the likelihood of the arc blow. Have you tried other grounding scenarios and different electrodes ?

Hi, I have a student who is preparing for a weld test soon. He has advised me that the test is a closed root coupon with a 45 degree groove angle and a 1/8th inch root opening with zero landing. But here is the kicker, the company wants a 6010 ran for the root and then filled and capped with 7018. Through my experience, this is not a common procedure due to it normally being for open root. He and I have attempted to perform this test but are having severe issues with arc blow and penetrating the backing bar. We have increased amperage and arc control and have tried various work angles, etc. By the way, we are also getting a terrible fingernail action near the midway point due to the closeness of the bevels. We have used both transformer and inverter machines with different internal 6010 settings but no luck. Can anyone give some insight on WHY this test is being requested? Also, if you have any tips for making the root successful, please reply back.

Thanks

Looks like arc blow, which I don't recall being a problem with aluminum? It would be fun to hack these photos onto a Fronius website ad, but if I had those skills I'd be on my yacht right now.

More ideas on modifying booths and fixtures in curing arc-blow here!

https://app.aws.org/forum/topic_show.pl?tid=9552

To make sure that you are not wasting a lot of time de-gaussing, you may have to re-design jigs/fixtures and booths to reduce occurrence. Read to the bottom of the previously mentioned Lincoln article below for some ideas on doing this.

http://www.lincolnelectric.com/en-us/support/welding-how-to/Pages/preventing-arc-blow-detail.aspx

Glad it helped, but pack a lunch my friend because the arc blow thing will be ongoing :)

But you will get better and better at dealing with it.

WE HAVE A HAND HELD GAUSS METER AND GOT READINGS OVER THE 20+ LIMITS. ARE BOOTHS ARE MAGNETIZED! THIS WHAT WE DID .ALL THE GOOD INFO. ALL OF YOU HAVE PIONTED ME TO WAS GOOD STUFF.SO ON AN OLD FORUM TOPIC ON ARC BLOW SOMETIME AROUND MAY OF 2015. I THINK IT WAS LAWRENCE! ON MAGNETIZED FIXTURES HE SAID TRAINING FIXTURES OFTEN BECOME MAGNETZED... SO HE SAID RUNNING AC CURRENT THROUGH EACH PART OF THE FIXTURE WILL HELP BREAK THAT UP.... A DEAD SHORT WITH A 5/32 ELECTRODE AND 100 AMPS UNTIL IT MELTS IS A VERY QUICK WAY TO BREAK UP MAGNETISM IN THE FIXTURE...SO LAST NIGHT ME AND MY LEAD WELDER HOWS NAME ALSO IS KEVIN! SET UP MY BIG DIIAL AN ARC  AC  MILLER WELDER. IT WOULD HANDLE THAT JOB WELL..IN ARE BOOTHS THERE IS A MAIN POLE IN WITCH ALL THE FXTURES AND WORK TABLE SLIDES UP AN DOWN.ALSO WE ARE BACK TO EACH FIXTUR IS GROUNDED SEPARATE. WE HOOKED THE NEGATIVE LEAD TO THE BASE OF THE POLE WITH FIXTURES IN PLACE AND WE TOOK THE POSITVE ELECTRODE HOOKED TO THE TOP OF POLE WIITH A DEAD  SHORT UNTILL IT MELTED PRETTY GOOD!!! AND THEN WE SET UP THE STANDARD TEST PLATE CONFIGRATOIN THAT WE HAVE ALWAYS USED AND I STILL CANT BELEAVE IT.. BUT THE ARC BLOW BACK WAS ALMOST COMPLETELY GONE!! THERE WAS A SLITE BIT OF BLOW AT THE VERRY END OF THE WELD. TEST...SO TODAY ILL BE REGROUNDING ALL THE FIXTURES. WE JUST DID ONE BOOTH LASTNIGHT.. AND THEN WE BE SHOCKING THE SH.......T OUT OF ALL THERE LITTLE BUTTS TODAY!! I GUESS WE WAIT AND SEE HOW LONG IT WILL LAST.. I HAVE NO PROBLEM SHOCKING THEM ON A REGULARE BASES IF IT WELL KEEP THE ARC BLOW UNDER CONTROLL MOST OF THE TIME!! I THANK YOU ALL FOR YOUR INPUT. IM OFF TO THE LAB TO DO A LITTLE BIT OF SHOCK TREATMENT ON MY LITTLE WELDING SCHOOL ....WILL TALK SOON.. HOPEFULLY THIS JUST MAY BE THE FIX WE WERE LOOKING FOR!!!!!!  AND WILL BE KEEPING ALL FINGERS CROSSED!! BEST REGARDS...... KEVIN AND THE OTHER KEVIN TO.....

ABOUT THE BOOTHS BEING ALL GROUNDED TOGETHER ? WE DID THAT TO TRY TO CHANGE THE ARC BLOW,SOMEONE GAVE US THE IDEA I  GUESS? BUT THE ARC BLOW HAD ALREADY BEGAIN. AND THATS THE ONLY THING THAT HAS CHANGED FROM THE FIRST START OF ARC BLOW. SO FARE.  SHOULD WE CHANGE BACK BEFORE TRYING ANY THING MORE? ALSO WE RAN A TEST PLATE OUT OF THE SHOP OFF MY WELDING RIGG AND NO ARC BLOW . WITH THE SAME TEST SET. SO WE TOOK THE WORK IN THE SHOP NOT IN THE BOOTH. STIL NO ARC BLOW.AS SOON WE PUT THE TEST IN THE BOOTH ON THE BOOTHS FIXTURE AN STILL RUNNIING OF THE RIGGS POWER.THE ARC BLOW CAME BACK! WHAT THE HE***** IS GOING ON? ARE THE BOOTHS THAT MAGNETIC TO DO THIS ? ALL ALONE BY ITS SELF. WITH NO         POWER FROM IN SIDE THE SHOP IN PLAY.       ALL TRY ANYTHING NOW?   SIN.KEVIN.

Hey Kevin,

This thread is powerful in it's collective experiences on how to handle magnetic arc blow:

https://app.aws.org/forum/topic_show.pl?tid=34424

Check this link out and remember to keep scrolling down in order to read the entire .pdf.

http://www.academia.edu/8144687/Magnetic_Arc_Blow

Here's an excellent paper from Lincoln Electric:

http://www.lincolnelectric.com/en-us/support/welding-how-to/Pages/preventing-arc-blow-detail.aspx

This one is a little more in depth:

http://www.diverse-technologies.net/literatu/zeroart.pdf

Btw, there are two types of arc blow... Thermal and Magnetic so, make sure you distinguish between the two before you start trying to correct the current conditions @ your school's lab... Also, a picture is worth a thousand words so post an image or two in order to help us understand better your situation. If you don't know how to post the pictures (images), don't worry because we will walk you through the routine. If this is not possible, then good luck and btw, Welcome to the AWS Welding Forum... Well, that's it for now because I need to go and rest a bit.

Respectfully,
Henry

Garrett,

I was thinking the same thing.  In fact, I think that was discussed in one of the previous threads dealing with arc blow.  Hopefully some of the more 'educated' within that arena will chime in. 

I know when doing larger projects in the shop or field we have had multiple machines grounded to the same member but those are usually pretty good sized components; petroleum storage tanks, large equipment, larger structural members and/or the entire building being erected.

Using several machines grounded together with a common ground in welding booths may be worth taking a look at.

Brent

https://app.aws.org/forum/forum_search.pl?words=arc+blow&user=&board=0&field=body&min=&max=&order=desc

Click this link and read.....there's more info than you can read in one sitting....bound to find something in there that will help your situation.

A note of caution; if welders switch between polarities the voltage could double because the connections would be in series. Arc blow can be mitigated by using a cable with two work clamps. Clamp One at the weld end and the other to the table or fixture to create a circular magnetic field instead of concentrating it at one end.

BRENT THANK YOU FOR YOUR HELP. I AM YUST THE CEO OF ARE COMPANY SO ALL  I CAN SAY IS MY LEAD INSTRUCTOR IS ON HIS WAY TO HELP WITH ANSWERS. I CAN TELL YOU IT ALL 7018 SMAW ROD ON STANDERD SERT. TEST PLATE CONFIGURATION . MORE WHEN HE,S HERE.  ALL ARE WELDERS ARE LINCOLN INVERTEC V275-S IN A ROW OF 8 BOOTHS GROUNDED TO GETHER . AND MY SPELLING HAS ARC BLOW KNOW TO I THINK.  THE LEADS ARE 2.0 GAGE WIRE WITH STANDARD CLAMPS. THE WELDERS ARE WIRED FOR 3PHS.AND ARE MOUNTED IN EACH BOOTH ON WALL NEXT TO WELDING FIXTURES. THATS ALL FOR KNOW. THANKS.  THE MAT. IS 1 IN.X6X3 FOR 3G SERTS.
AND THE ROD IS 1/8 SIZE THE JIONT CONG.IS A V GROVE BUTT YOINT WITH BACKING PLATE.IS 1/4X1.5 WIDE. AND MY GUY IS HERE KNOW.IS  THERE MORE YOU NEED TO ASK.

So, Kevin asked about arc blow information to help out a welding school he is part of.  They are having some issues that they have not been able to resolve and thus far those assisting them have been of no help.

Let's see what we can do.

Now, Kevin, we need to know a few things:
1) Welding Process: SMAW, FCAW, GMAW, GTAW, etc.
2) Welding Procedures: Volts, amps/wire feed speed, electrode class and size, gas for shielding (75/25, 90/10, 100% CO2, etc) and its flow rate,
3) Materials to be joined: grade and thickness
4) Joint configuration: T-joint, butt joint, corner joint, etc.
5) Size of work lead and how is it attached to the member in process?
6) A picture would really be nice if you could.

He Is In Control, Have a Great Day,  Brent

Kevin,

I'm going to start a new thread for you, watch for a title on 'Arc Blow'.  It will be in a different section that will be more applicable.  Besides Weldingfool's suggestion of using the 'Search' function, I think you will get more responses that way.

I will be asking a bunch of questions in order to be more understanding of your situation.

Brent

THANKS BRENT. DO YOU HAVE INFO ON DC ARC BLOW? IM STUCK IN ARC BLOW LIMBO!

I NEED GOOD INFO.  ON DC ARC BLOW BACK. HOW TO STOP IT? FROM KEVIN MCDONALD. MY SCHOOL IS FRANTIC.ITS STOPING THERE TESTING. AND I HAVE CALLED EVERY ONE I COULD THINK OF IN THE FEELD. THEY SAY THERE WORKING ON IT . THANKS ! P.S MY WEB SIGHT IS WWW.ALLIED WELDING SCHOOL.ORG ANY HELP WOULD BE GREAT!

thank you for the info. my bad! just joined your group. so i will get the hang of it? thanks again!  P.S NO I WILL NOT TRY TO TEACH MY STUDENTS HOW  TO SPELL!  BEST TO YOU. KEVIN MR ARC BLOW

A couple of suggestions:
-Post your questions in the appropriate section, you will get better response. Better yet, start your own thread related to needs for your new school (looked at your website, good stuff)
-There are many threads already on this forum related to arc-blow (use the search function), although they get a little technical for my blood, there is some great information there. It's saved my butt countless times!
-I hope you're not teaching those kids grammatical skills...

ENNYTHING ON ARC BLOW NEW THAT IS WERTH TRYING ? i have a new welding school and after opening in november of last year! just before testing for certifing time i got a GIANT case of ARC BLOW ! KNOW ONE SO FAR HAS NO ANNSWERS! please HELP MY SCHOOL. WWW.ALLIED WELDING SCHOOL.ORG. ALL IS UP IN THE AIR WHATING ON ALL THE BIG SHOTS THAT I HAVE CALLED AND CAME AND ISAW AND IM STILL WAITING TO HEAR FROM THEM. SO THIS MUST BE FOR REAL.

Yes, First arc DCEP for penetration Second Arc AC minimizes magnetic arc blow and Last Arc DCEN for higher deposition rate. Arcs spaced 1/2 in to 1 in or greater, using caution that the slag remains molten. Another configuration would be first arc DCEP and the two trailing arcs AC.