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Up Topic Welding Industry / Technical Discussions / Slag Stacking
- - By Matthew Nemchek (*) Date 01-21-2012 22:33
Hello,

What is the official view with regards to the practice of "slag stacking" the method of not inter pass cleaning large weldment's until another layer is finished using FCAW. Talking about weld sizes as small as 1/2" - 2" I have found slag in the shop area containing 8+ weld passes in it. I have over heard supervisors stating this practice was OK as long as it wasn't done while filling a bevel. The welders who commonly do this also have a high occurrence of exploding welds. I have seen a guy welding along with 3/32" core wire and run over a prior weld pass only to hear what sounded like a black cat going off. The welder had his trigger lock on when this occurred, and was installing the first stringer pass after he had cleaned a layer of slag off of his previous stack. The explosion was so powerful it actually stopped his welding machine cold. He had to restart his weld pass mid weld and fill in the hole that was left.

I have always been taught that each weld pass gets cleaned of slag and cleaned of debris prior to adding the next pass... no excuses. Did something happen, or come along that makes this practice acceptable?
Parent - By 803056 (*****) Date 01-22-2012 01:53
It sounds like you've answered your own question.

Al
Parent - - By Lawrence (*****) Date 01-22-2012 05:05
Bucyrus or P&H  ??

Oh.. and welcome to the forum Matthew!
Parent - - By Matthew Nemchek (*) Date 01-22-2012 16:17
From what I am told they used to work at Bucyrus for a time. I personally never worked at B.E. (now owned by Caterpillar). I currently work for a Union shop called Telsmith. They are going to implement D1.1 due to customer demands. The problem is going to be changing the bad habits of the guys who are currently employed there now. Its going to be very difficult to remove the welders who continue to use poor welding practices.

I want to know if anyone else has noticed this practice spreading and becoming more commonplace? I hasn't mattered what shop I go to, there are always 2+ guys who do this and will bitterly defend the practice.

Thanks for the welcome. I get to test for my CWI at the end of February.
Parent - - By Blaster (***) Date 01-22-2012 20:05
Why would it be hard to get rid of welders who won't follow directions?

I can't think of an easier or more valid reason to fire a guy.

As far as welding over slag goes, a good welder under a lot of conditions should be able to run more than one pass without cleaning slag from a previous bead and still put in perfectly sound metal.  What possible metalurgical effects may result from this practice, I have no idea.  I would like to know.  But a good welder should be able to do this under a lot of conditions without creating additional discontinuities.... depends on the position, groove angle, width in the groove, slag/electrode type, and operating parameters.  Of course there is a lot more to being a "good" welder than just having a steady hand and being able to weld straight.

I know some welders in manufacturing shops like to do this in an attempt to relieve the boredom of repetitive non-challenging joints.

That said, I think it is generally poor practice and I can't think of a good reason to do it.
Parent - By Matthew Nemchek (*) Date 01-22-2012 21:49
Its difficult because of the union. With out getting to elaborate the company gets forced to either offer their job back, or is forced to pay the employee in exchange for their resignation. At all the non union shops this isn't an issue at all, but over where I am at it happens all the time. There have even been some seriously unbelievable instances where people got hurt intentionally and the company had to buy off their resignation to get rid of the problem employee.

The reason they state they use this practice is so that they have a shelf to keep their weld from drooling out when they are putting in multiple passes. They claim it allows the passes to blend into each other better creating a smoother weld face on large multiple passes. The wire we use welds with a convex profile on the weld face. If you turn up the heat on it to where I previously used to run the same sized core wire at other shops it causes severe undercut. Most of these guys run it to hot and install uneven toe welds that if you try to weld over them they explode every so often. As far as a good welder being able to do this and not get inclusions... I may have only met 2 in my experience that could potentially do this, but even then they would refuse to compromise their integrity to take a short cut. All the welds we weld are in the flat. 1F and 1G. It really doesn't get much easier than this. If it did they would hit a button and a robot would do it for them. I personally have never heard of the practice being acceptable ever with exception to welding over a 6011 pass with 7018. I didn't know if they have created a wire that would make this practice acceptable?  

There are jobs at this shop like most that are "rush" jobs but the work environment is majorly relaxed. Even if the job is "hot" the management doesn't go out and lean on anyone or start yelling to get it done. Every welder has the opportunity to take their time and do it the right way the first time.

The pic below is how the guy who claims to be the "Best welder" in the shop thought was an acceptable way to fix a weld that was both undersized and lop sided. I got to arc this mess out and install it properly.
Parent - - By swsweld (****) Date 01-22-2012 20:49
Matthew,
If you are using D1.1 you can reference 5:30 Weld Cleaning. In Process Cleaning states Before welding over previously welded material all slag shall be removed and the weld and the adjacent base metal shall be cleaned by brushing or other suitable means...it applies to successive layers and successive beads.

Of course, to many welders, these are just words. getting production supervision to support you will determine if you can get the welders in question to change their bad habits.
The same technique exist in the boiler tube welding world called slag welding.

Good luck on your upcoming test, study, study, study.

Wish I knew how to copy/paste from pdf on a Mac? Would have posted the entire verbiage.
Parent - - By Matthew Nemchek (*) Date 01-22-2012 22:06
Thanks for the advice. I can when I get my copy of D1.1, but that won't be until the seminar starts.

I understand what you mean as far as words. These guys tend to form cliques with like minded welders so they have more than just themselves to try to argue for how they weld.

I have been doing what I can to get ready for the test. Anything helpful to look at and study will always be appreciated. My main point of concern is the code book itself. I have never had the opportunity to look through one much less read what was contained in it.
Parent - By 803056 (*****) Date 01-22-2012 22:18
It is difficult to meet code requirements if you don't know what those requirements are.

I fired a welder several years ago because he wouldn't slag between weld beads. I warned him once and told him that I would fire him if I saw him welding over slag again. He told me I couldn't fire him because I wasn't his boss.

He was right, I wasn't his boss. I was the project manager for the welded repair and I took the job with the agreement that I could fire any welder that refused to follow my direction. He found out when I climbed the ladder and handed him is paycheck and an airline (coach class) back to Milwaukee. I didn’t have to warn any of the remaining welders. They followed my work instructions to a “T”.

Best regards –Al
Parent - - By aevald (*****) Date 01-22-2012 22:47 Edited 01-22-2012 23:04
Hello Matthew, I am not quite sure why this site actually has a readable Code attached to it, but it does. Here is a readable version of the AWS D1.1 2010 code book. I am pretty sure that you can navigate to the page and section that the other forum members have eluded to to make your case. Good luck and best regards, Allan

http://www.scribd.com/portesfernando/d/63915971-AWS-D1-1-2010

EDIT: As I am not in support of copyright infringement, although this site has this available for "download" I wouldn't touch that with a ten foot pole and definitely wouldn't do it. I have read some of it as I scrolled down since I was surprised to see it in it's entirety and it is entirely there.
Parent - By Matthew Nemchek (*) Date 01-23-2012 04:08
Very nice thank you.
Parent - - By 99205 (***) Date 01-23-2012 05:25 Edited 01-23-2012 05:28
Hmm, after I clicked on that site, my Anti-virus shut down.  I think I'll stick to my real copy.  It would be handy to be able to load Codes onto a Tablet or Smart Phone.
Parent - - By aevald (*****) Date 01-23-2012 06:00
Hello Doug, I didn't notice any virus type stuff when I first opened that up, no flags, or anything else. Actually got to that through Google when I was researching some information for a different question elsewhere. I've got Norton on my laptop at home and that is where I opened this up from. I certainly didn't intend for anyone to get a virus, hope that isn't what it was intended for. Best regards, Allan
Parent - By 99205 (***) Date 01-23-2012 13:27
I've got Norton too.  I did a scan after I noticed my Anti-virus turned off and didn't come up with anything.  I just thought it was a strange occurrence.
Parent - By Matthew Nemchek (*) Date 01-23-2012 21:39
I went there and opened it up. Its all good. IDK why your AV shut down. I personally do not even use an anti virus. They are notorious resource hogs and only help slow things down on your pc.
Parent - - By js55 (*****) Date 01-23-2012 13:45
As stated by another post, and from a practical point of view, it can be done within limits. Done it myself back in the day. It takes some skill to do it successfully. You have to work the slag with the wire. Actually push it out of the way. You cannot run over the top of it. You will actually feel the slag resist the movement of the wire as you push the slag out of the way. If you are not working the slag in this manner you will not be successful. I personally now do not think it good practice. And the code of construction must be complied with under all circumstances.
Parent - By joe pirie (***) Date 01-23-2012 14:07
If the whole group refuses to clean their welds between passes simply reject every weld they do till they complain
makes your job real easy. You'll find out real quick whos side management  is on lol
Parent - - By jwright650 (*****) Date 01-23-2012 14:48
Bad practice and code requirements aside, I realize how it's done and have seen it done successfully, but.....now you have to prove to others that the welds are OK. That isn't as easy as it sounds. Alot of times it is just quicker and less expensive to cut it out and reweld than to try to prove that it was OK as is.
Parent - By Matthew Nemchek (*) Date 01-24-2012 03:28
Thanks for all the replies guys. Was wondering if this was becoming more common because it seems that way from my end.
Up Topic Welding Industry / Technical Discussions / Slag Stacking

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