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Up Topic American Welding Society Services / Certifications / Metal Core welder performance test
- - By marktski (**) Date 12-19-2013 13:54 Edited 12-19-2013 15:26
If my WPS lists shield gas as a range 75-95% Argon, remainder CO2 as the wire manufacturer suggests.
Is a welder who takes his performance test with C25 also qualified to C90? D1.1 code I don't see gas listed
in table 4.12.
Parent - By Lawrence (*****) Date 12-19-2013 16:12 Edited 12-19-2013 16:20
To answer your question.. Yes.  The welder is qualified, assuming other essential variables comply.   Shield gas is not an essential variable in welder performance qualification.  But transfer mode is.

However you mention that your "WPS lists shield gas as a range 75-95% Argon, remainder CO2"
This cannot be correct if D1.1 is the code you must comply with.

Using a gas mixture within the "range" set by the manufacturer is wise.. But the mixture percentage used in production must be clearly stated in the procedure, whether it is prequalified or qualified by testing.  A change in shield gas mix percentage would requre a revised Prequalified WPS to be generated and if the procedure were qualified by testing a new PQR would need to be done.

What you CAN'T do is make production welds with C25 and switch to C10 and continue to use the same WPS.

See Table Table 4.5 (19)
and
              Table 3.8 (15)

Edit: 
If you are running 75/25 Argon\C02   I doubt you are running spray transfer.   Typically 80% minimum inert gas is required for this unless some sort of pulsation is employed
Parent - - By welderbrent (*****) Date 12-19-2013 16:37
What Lawrence didn't continue with in thought is that D1.1 only pre-approves GMAW in the Spray Transfer mode.  Thus you would need to be using 80-98% Ar with the balance in either CO2 or O2 depending upon application and percent of Ar.

When you drop below 80% it will be assumed you are working with Short Circuit Transfer or have a PQR which will restrict the gas percentage very tight without re-qualification. 

The electrode manufacturer may list all gases the wire is compatible with but that doesn't mean any gas will qualify for a specific application. 

But, to your question, the welder's qualification is okay.  You can change many things and still not be required to retest your welders.

Have a Great Day,  Brent
Parent - - By Lawrence (*****) Date 12-19-2013 16:49
Let me help you a little too Brent.

Globular transfer is still considered a prequalifed transfer mode for GMAW/FCAW and can be achieved with argon values less than 80%  (not that I would recommend it)    This bold statement is verified in the code :)

"C-Table 3.7 Requirements for GMAW/FCAW. This
section provides the requirements for GMAW and
FCAW WPSs when prequalified WPSs are used.
The gas shielding at the point of welding is to be
protected from the wind to prevent interruption in shielding
and resulting contamination of the weld by the
atmosphere.
The prequalified provisions apply only to GMAW using
spray and globular transfer modes of metal deposition
...."

We are straying a bit from the reservation on this, but I enjoy technical discussion.
Parent - - By 803056 (*****) Date 12-19-2013 18:23
Which edition of D1.1 was that excerpt from the commentary (C-Table 3.7) taken Larry?

It is interesting to note the limitations imposed on amperage in Table 3.8 when welding with GMAW. The 10% limitation on amperage would seem to exclude pulsed spray transfer being prequalified considering the back ground current is typically a low percentage of the peak pulse current.

I wonder if AWS D1 committee has taken a stand on the status of pulsed spray transfer. I have my personal views on the issue, but that changes the scope of the question.

Best regards - Al
Parent - - By Lawrence (*****) Date 12-19-2013 18:34 Edited 12-19-2013 19:23
Al,

I quoted it from 2010, but the text remains exactly the same all the way back to 2004

Current is not a problem if it is agrigated... Who gives a crap if the current varies 10% or 50% when that variance occurs within 1/5000th of a second on possibly 16 or 32 channels of your ossiliscope Al?

If it is an open arc, if the droplets are smaller than the filler wire diameter, if the droplets are deposited axially, if the welding arc demonstrates a CV nature, it's spray transfer     Pulse or not pulsed.

Edit:
You're darned right the D1.1 committee should make a clear distinction that GMAWP is prequalified.
The CWB did  :)

.
Parent - - By 803056 (*****) Date 12-20-2013 13:42
It makes no difference unless you believe welding is a "controlled process" and consistency and repeatability a goals of production. I was under the impression the reason for using a WPS was to help meet those objectives.

If the industry needs no control, there is always the Farm Code. It sees wide applications. "Just git it done", works in some industrial sectors.

In the past you and I were in agreement that what "works" on one machine model does not necessarily work on a different model. The "average" values registered by the voltmeters and ammeters are of little significance when moving from one machine model to a different model produced by a different manufacturer.

How quickly one can move to the "Dark Side." :eek:

Best regards - Al
Parent - - By Lawrence (*****) Date 12-30-2013 14:19 Edited 12-30-2013 17:16
Hey Al,

Sorry It has taken so long to respond... Been traveling.

I wouldn't say "Dark Side"  just yet.

My main objection with GMAWP as related to D1.1 has ALWAYS been 3.2.4 (for those who don't know, it is a limitation on Prequalified GMAW/FCAW to CV power only)   The clause was originally provided to limit the prequalification of GMAW operations from CC generator type welding power sources with suitcase feeders often used in field welding...  But the letter of the clause also spoke to some GMAWP power supplies, even if it was not the intention of the code writers.

Edit:  What this means is that GMAW/FCAW operations with CC (Constant Current) typically produces a welding arc that when the contact tip to work distance (CTWD or stickout) is changed the voltage will vary dramatically; and transfer modes and spray transfer arc lengths almost always depend on arc voltage to define themselves.   This arc tendency makes for great difficulty when GMAW operations are manual and operator control of the CTWD varies even slightly....   Early GMAWP power supplies often used CC power supplies and making consistant manual pulsed welds were difficult at best.   Newer *synergic* GMAWP power supplies produce CV type welding arcs that have a "spray" type transfer and will keep a consistant arc length (voltage) even as the operator makes typical changes in CTWD.

Any GMAWP power supply on the market sold in America today (that I know of) produces a welding arc that can be accuratly described as an arc with Constant Voltage behavior....     Back when I was a big critic, this was not the case...  Most pendants for GMAWP were 5 level manual knobs or digitally adjustable.

Typically now the waveforms are propriatary, and the frequency in Hz and the number of cascaded and  overlayed "channels" of electrical power that are put out of a typical GMAWP power supply....  Your occilliscope would be of zero value trying to capture current.......  This is why the products have built in *aggrigators* to capture current values for welds that are produced with GMAWP... These are calibratable Al and quite accurate, as the "scope" is built into the power supply and designed especially for the purpose of measuring welding current at the rates and volumes that the machine produces.

I do still think that a solid WPS should have one of these two things when dealing with GMAWP
  1.    All programs and subroutines (hot start, trim values, crater fill etc) should be noted for the welder to follow.
  2.    All programs and subroutines should be locked so that the welder cannot adjust them.  Anything that the operator can    adjust should be noted in the WPS

I'm all about control Al...... I want the welders especially to be controlled (both the machines and the People) with an absolute minimum of room provided in WFS and Voltage for the operator to "play around with".

I have absolutly no objection to GMAWP being a prequalified process, given the assumption that the welding arc has a CV behavior and there is a mechinisim to obtain essential electrical values....
Parent - By welderbrent (*****) Date 12-30-2013 16:49
Interesting.  Thanks for that info Lawrence.  I know I have been chided previously for some of my stands on both Pulsed and Globular but that rather sums up some of my concerns as well.  Operators are too prone to making adjustments outside of tested, proven, documented and approved parameters.  I think some issues need to be clarified within the industry and especially the codes.  That does not mean there is absolutely no place for these processes.  Technology is a great thing.  I am not one to oppose all change.  But new things have to be watched, tested, proven. 

We all get the welders who think it is terrible that we would even suggest removing any amount of control from them.  I won't take the space to go through all of the objections and snide comments.  They think the whole WPS and machines that lock them out are going too far and removing their ability to get the job done.  But the truth is they, and some of us when we were there before becoming inspectors, have brought it upon themselves.  Many of us can recall times we changed a machine and did a job in a non orthodox method.  The Northridge earthquake was just one of the more dramatic events that brought many factors into the light and caused a lot of change because of this very issue. 

Now we have a system that does not totally exclude short arc, GTAW, and many other processes, but it does bring it into additional testing to prove the contractor and their welders understand the limitations, have proven they have a correct set of parameters to accomplish the job, and are willing to be monitored to prove they have stayed within those parameters.

That said, for the average person, I still think these are not a wise choice.  It takes training, testing, and experience along with a great desire to be true to the limitations imposed to make it work.  And it is difficult to monitor some of these for the reasons you name as well as the FACT that most of us do not have the resources behind us to get some of the very expensive equipment that would be needed to monitor them as they need to be. 

Bottom line once again, it is up to the engineers, contractor, and inspectors to get a process approved before beginning a job that all can agree will accomplish the work at hand in a satisfactory and successful way with the ability of the inspectors to verify compliance and the ability of the contractor to make money while also producing safe, satisfactory, compliant welds and products.

Many of those same welders named above have more than once claimed they were using Globular when they don't have a clue how to get there or what the difference is between Short Circuit Transfer, Globular, and Spray.  Most of them can't even tell you rather they are using FCAW or GMAW.  Many of them think that being qualified to any one wire electrode process means they can use any at all wire electrode process.  Metal-core, innershield, dual-shield, solid wire gas shielded, etc.  And I agree, it can be confusing in its multitude of specifications and classifications.  But they need to check it out before they begin the job and make sure they are qualified in the one they want to use.

That's why we are supposed to have pre-fabrication meetings, that I have almost never been called in for.  Always backtracking because they have at least part if not all of the work done before they call us. 

If engineers and City Building Officials would stand solid and back us up and make them do it right we would not be going over this so often.  They like playing dumb and then asking forgiveness later.  And way too often the engineers and city officials let them slide.

Now, I know I have gone a little astray from the OP here.  Just my two tin pennies worth on the matter of both Pulsed and Globular, both of which managed to come up here in this thread.

Have a Great Day,  Brent
Parent - - By welderbrent (*****) Date 12-19-2013 18:47
I will bite tongue and be good, thanks for the "help" Lawrence. 

My views of Globular are probably pretty well identified with Al's in some respects and are totally all my own in other respects. 

Ultimately, regardless of the ways industry has found to use it and regardless of any code committee approval or at least inclusion of it in codes....it is still just a misadjusted machine.  Either tweek it up and change the gas and run spray, or, turn it down and adjust the wire feed speed and run short. 

Most of us have found lots of ways to modify a correct process to get something done but that doesn't make it right and worth assigning it's own name and calling it a mode of transfer. 

And, while this is off topic I think it does have application to what is going on with the OP.  It appears someone thinks they can adjust the code to mean what they want and make a contractor bend over backwards because they are incorporating their own private interpretation.  A popular quote from the Scriptures seems appropriate with a little modification:  2Pe 1:20 "Knowing this first, that no prophecy of the scripture is of any private interpretation."  Well, it applies to codes as well.  If it isn't clear, call Miami.  You can get an unofficial explanation within a day or two.  But, as with many other things, pure truth takes a little longer; in other words, code committees issuing official interpretations will wait a couple of years by the time it goes through all the channels.  But it appears that the only way this will be resolved for the OP is to get someone the TPI will yield to to issue a decision. 

Only time will tell.

Have a Great Day,  Brent
Parent - - By Lawrence (*****) Date 12-19-2013 19:13
Brent,

I'm not proponant of globular transfer, just yanking your chain.

I hold it with the same regard as "slugging"   

Were in the 21st century folks :)
Parent - - By welderbrent (*****) Date 12-19-2013 19:49
Lawrence,

It's good, I was pretty sure I remembered you as being skeptical about the features and uses of Globular. 

Another one of those internet miscommunications. 

Also, I just noticed I rather mixed threads, added a comment that applied more to another thread.  Overall, it's still good so will leave it as is.

Have a Great Day,  Brent
Parent - - By ssbn727 (*****) Date 12-23-2013 08:01 Edited 12-23-2013 08:03
I'm just glad I'm wearing my waders in here because the crap sure is running high lately!!!

One can indeed use GMAW globular transfer in certain, special circumstances such as some types of  repair work where it's the only method of transfer that's suitable for the specific situation and is in fact pre-qualified but, it's not a preferred method to use in production... I have seen some applications in shipyard work where the WPS specifically stated that the method of transfer was to be Globular as opposed to spray and there are still, or at least there were one or two power source manufacturer's that would fine tune their machines to run some pretty beautiful as well as code compliant welds so, there are indeed applications that prefer to use globular transfer... What I don't see is where Al even mentions the term "Gobular" or am I losing my eyesight??? Maybe he used invisible ink???:eek::roll::wink::lol::lol::lol:

Finally, what method of transfer do you think is used with SMAW???That's right! It's GLOBULAR!!! FCAW can be tuned in to run very similar to SMAW using Globular transfer...

So each method of transfer does indeed serve their purpose in various industrial welding applications...
Misadjusted??? Not if it's the intended method of transfer! Everything has it's place and role to play.:smile::cool:

Respectfully,
Henry
Parent - By welderbrent (*****) Date 12-23-2013 13:15
Henry,

Lawrence answered the original question with some info to which Al asked a question about the source in regards to pulsed usage.  They went back and forth a couple of times.  But within Lawrence's answer was a comment directed toward globular.  So, I was conversing with him about that.   You are right, Al said nothing about globular, though he did ask Lawrence where the quotes had come from concerning info about globular and then commented about pulsed.

Me, I'm just an outside trouble maker, throwing out my two tin pennies of personal opinion which qualifies for any of the infamous applications of opinions one would care to attach to it. 

I understand your comments about how the precise workings of SMAW and occasionally FCAW function in the arc in order to transfer material.  But in it's application of operation when used for GMAW I have great reservations.

Now, that is not to say it does not have a place.  I see it in automotive but the results are far from what I consider to be good or even acceptable.  I have seen few uses where it could not be done much more properly within the limits of either spray or short arc transfers. 

You have seen much more than I.  You have been involved in much more technical applications than I.  Or than a good many others as well.  I respect your position. 

Where I run into problems with Globular is that way too many fabricators THINK they know what they are doing and attempt to claim they are using Globular on structural jobs just to excuse their lack of switching to spray but they turned the short arc way up.  And, they are not qualified/certified in it's operation anyway.  All they have done is try to skip proper procedures.  They have no WPS's or certs to operate within the bounds of Globular. 

Anyway, best wishes for the Holidays Henry.  Glad you are doing well. 

Have a Great Day,  Brent
Up Topic American Welding Society Services / Certifications / Metal Core welder performance test

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