Having lived through early-mid 1990s genesis of GMAWP I can say with confidence that there are still GMAWP power supplies out in shops that run on 100% CC power.
1. This means that as electrode extension changes voltage changes wildly. Can't be prequalified via Section 3.
3.2.4 FCAW and GMAW Power sources. FCAW
and GMAW that is done with prequalified WPSs shall
be performed using constant voltage (CV) power supplies"
3.2.4 was placed with voltage sensing suitcase feeders and CC power supplies (Think SA200) in mind..... But facts are facts and if the power is CC than it ain't prequalified.
There are many generations of JUNK GMAWP.... Maxtron, ARCPAC, Pheonix and XMT with D60X style feeders...... Oh what a nightmare! Some are synergic some are not and the very meaning of synergic has evolved within brands.
It's complicated.
Good news is that new generation power supplies..... Lincoln , Miller, Fronius All have GMAWP that control (keep constant) both voltage and amprerage as the electrode extension <stickout> changes! They finally work as advertised......(though I still see no reason to use them for fillet welds in plain carbon steel >1/8")
Anyhow new power supplies can be tied into "Trim/Arc length" values, WFS, Program, Crater Fill values etc directly to a WPS... If the values are obeyed, you will have "OPEN ARC SPRAY TRANSFER" and I'm just too tired to argue that it's not prequalified any more.
I've given up on arguing code compliance and validity......... I actually got Ed Craig on the line for this one and he got angry and told me; "If it works, who cares" "stop wasting my time Larry"
So I still enjoy the technical side of the discussion... But I"m going to let the other puppies chew on each others necks when it comes to D1.1 compliance
PS/Edit
Al convinced me some time back..... I don't use the word "interpret" when discussing code compliance... I obey the code.. I navigate the code book... I worry somewhat less about lawyers this way.
Lawrence,
Don't tire of 'arguing'. I'm not arguing. I want it to make sense, and not just to me. I'm sure many others are reading and will read this thread. I simply tried to present my understanding of the various sections and applications of code and process. Now I want to know if my reasoning is 'reasonable'.
I appreciate the direction of you and Al as to wording and will try to watch that one. We need to check with code committees for 'interpretations'.
Some of your other points also, to me, show the importance of being qualified, not, pre-qualified. How can anything that has so many possible variables, even if the power source is correct, be a valid pre-approved procedure? If it is that questionable, how can anyone in a position of authority stand behind a blanket statement like "if it works, who cares"? That does not answer the question! First, who proved it worked? I see no evidence that it can be used successfully without going through the process of proving that the perameters are truly performing as required.
Sorry guys. At this point, I still stand by my previously stated understanding. Actually, I just hope no one on one of my jobs wants to use it for any structural work until we can get a very clear 'Interpretation' of this or change of wording from the D1 committee for the next edition.
Have a Great Day, Brent
Brent...
I'm sorry if it came across that I was complaining about your post... Nothing could be further from the truth!
I've just been gnawing on this bone for almost a decade!
Or at least since 2003 when I took over a shop with 5 GMAWP power supplies (horrible old ones)
I now have the flashy Lincoln Powerwaves, A Fronius CMT, Miller Axess and 350P and two of the newest Invisions on the way..... Still I can't answer the code compliance question with authority.
But the authorities I have spoken with and the guys on the D1 committee I know assure me that the intent is for GMAWP to be viewed as Prequalified......
I don't endorse this or reject it anymore...... I just make welds and write ever more complicated WPS's
Hello all;
Just a point of information, going back to my copy of D1.1-79, GMAW short circuiting transfer was not considered a prequalified welding process. Clause 1.3.1 of D1.1-79 includes the statement: "GMAW (except short circuiting transfer), .................shall be deemed as prequalified ......." The concern that SC transfer simply doesn't provide the heat input required to produce welds without fusion type defects and discontinuities has been a long standing issue.
Short circuiting transfer has potential problems, but the same can be said of GMAW-P if the welder adjusts the parameters outside the ranges validated by the contractor and listed in the WPS. The same can be said about spray or globular transfer, except, if the welder reduces the parameters low enough to be problematic, it becomes fairly obvious by the sound of the welding arc. With pulsing, the welder can reduce the heat input, i.e., the duration and frequency, to the point where fusion defects may be a problem, yet, the sound of the arc is still as if it is a pulsing spray. It must be said that pulsing is different than short circuiting in one major respect, which is how the molten metal is transferred across the arc. When pulsing is set properly, metal transfer occurs while the arc is in the spray mode, i.e., peak amperage. In the case of short circuiting, the transfer occurs when the electrode is shorted against the semi-molten weld pool. When in the pulse spray mode the current is relatively high during the pulse when compared to the short circuiting current while the electrode is shorted against the weld pool (while in the short circuiting mode).
As is always the case, the contractor has a responsibility to ensure the WPS will produce the desired welds with the desired properties and free of rejectable discontinuities. Once the parameters have been verified, it is still the contractor's responsibility to ensure the welders are working within the acceptable ranges that ensures sound welds.
Codes such as AWS or ASME set the minimum requirements that have to be met. That doesn't mean the contractor is in the clear if the minimum requirements are met. The contractor is still responsible for any work performed by their employees as well as any work completed by their subcontractors. It is prudent for the contractor to take whatever steps are necessary to ensure the product delivered will perform as expected. To that end, the contractor, even when the process is deemed prequalified, can conduct an abbreviated regiment of testing to validate the WPS. The testing should demonstrate the WPS will produce welds that will perform as expected even if said testing isn't mandated by the welding standard.
I have qualified WPS that utilized pulsing and as is the case with any transfer mode, there are ranges for the parameters that produce acceptable results. In my humble opinion, the WPS should include reasonable ranges that can be used by the average welder and will produce acceptable results. If that isn't the case, I agree with the welder that states the WPS should be left in the Port-A-Potty where it can serve a useful purpose.
Whether the applicable code requires the WPS using pulsing transfer to be qualified by testing or whether it is prequalified is immaterial if the WPS used by the welder doesn't provide the information necessary to set the machine and produce acceptable results. I go back to my original statement that D1.1 does state that in order to be considered prequalified the power supply must be CV. If it isn't, the WPS must be qualified by testing. It is an easy matter to determine whether the program is responding as a CV or CC power supply as the welder varies the electrode extension or contact tip to work distance, or electrical stickout (a rose by any other name is still a rose). In Palin's case, with or without lipstick, a pig is a pig is a pig.
As for the inspector's responsibility in this matter; it is the Engineer's responsibility to review and approve the contractor's WPSs. Many Engineers (not all of them) will delegate the review to a CWI or SCWI. However, even when the responsibility is delegated by the Engineer, the CWI/SCWI is only acting in the roll as an advisor to the Engineer. It is still the Engineer's responsibility to accept or reject the contractor's WPSs. The CWI/SCWI's roll as a communicator is to provide the Engineer with sufficient information that he/she can make a reasonable decision. Whether the WPS is suitable for the work that will be performed is entirely the Engineer's responsibility. Noticed I intentionally did not say the WPS met the code. In the case of D1.1 the Engineer has the latitude to say the WPS is "good enough". So, it is possible that even if the WPS (or welder's qualifications) do not meet the code in its entirety, it can be "good enough" for the purposes of the project.
Wish me luck. Tomorrow I have to attend a preparation meeting for a future deposition. Time spent with a lawyer is always an educational event. I'm just happy I work for the plaintiff. And as is the case with any education, someone is paying dearly. It is a case where the contractor said "good enough", not the Engineer.
Best regards - Al
Thank you for that information Al. I'm wondering how so many welders from back in the early 80's (myself included) have certs for D1.1 with GMAW-S? I know mine were only RT. No bend test, at least on the paperwork. And no Clause 4 paperwork or testing that I ever saw or was told about (doesn't mean it didn't happen). Interesting.
I understand that ALL WPS's can be ignored by welders thus invalidating the entire procedure. But for pulse, how does one go about making sure the WPS is written withing levels that are acceptable for a Pre-Qualified WPS and then that the welder is following it? It is fairly easy to check all essential variables for GMAW, FCAW, SMAW and see if the WPS is written within manufacturer's specifications for a particular product and code for other variables. But how about Pulsed? Who has done the testing and where do we find it for verification that the WPS is correct? I don't see anything in any of the tables, clauses, of D1.1 that guide me as to settings for pulse; which are acceptable and which are not.
I know that much is within the responsibility of the contractor. But I must be able to verify it. So must the engineer. And how many will test the qualification of a process they believe to be pre-approved? Not very many I'm thinking.
I guess I am out of my league on this one. Again, just hope no one wants to use it around here until I have something clearer.
Have a Great Day, Brent
You are not alone on this issue. Lawrence and I have had many of the same concerns. There is no easy answer because every manufacturer has a different idea of how to create the best operational environment for the welding arc. Each approach is patented which makes it impossible to standardize the process.
In my humble opinion the only way to properly document the welding parameters on the PQR is to use a multi-channel oscilloscope so the variables such as up-slope, duration, down-slope, peak current, back ground current, peak voltage, back ground voltage, frequency, etc. can be recorded. Since that isn't generally possible, I qualify the WPS to a specific manufacturer and model and a specific program. Hold everything, according to ASME Section IX those are nonessential variables and need not be recorded on the PQR. Talk about head in the sand, hands over the ears, foot in my mouth!
I for one cannot shoot too many holes in your case. I don't believe Lawrence is saying you are off track either. Your concerns are valid, but not addressed by the codes. Let's not forget there are committee members that work for the major manufacturers and they hold considerable sway when it comes time to voting on a specific proposal.
You can imagine what is going on behind closed doors in regards to phased array UT? Don't think for a minute the big players in the wonderful world of UT aren't wining, dining, and twisting a few arms to make their case for the newer more expensive UT machines.
Smarter people than me sit on those committees. The well being of our families are in their hands. I don't know about you, but it scares the hell out of me.
I worked on the first Civic Center in Hartford, Connecticut. I was a connector on the steel framing. As an apprentice Ironworker I voiced my concerns and was told by a project engineer, "Kid we pay you to put the building up, not to analyze it."
My family had tickets to go to the circus at the completed Civic Center and I wouldn't let them go. I was a bum to a lot of family members. My bum status changed about four months later when it collapsed. The building only stood for two or three years before a small snow storm bought it down.
Yup, I’m only a dummy welder, but even when the experts say it’s safe, I know enough to stay out of building to don’t look safe to me.
My motto is "Do what's right. If it doesn't feel right, it probably isn't."
Best regards – Al
Al,
I do truly believe your opinion to be presented with a true spirit of humility. Lawrence's too. But they are still both very respected and sought out with many of us quoting and putting a lot of weight for the decisions we have to make on the information you present.
When at FabTech last year I had several people tell me that all the committee's REALLY could use and desire to have more CWI's taking an active part. Problem, most of us work for ourselves and don't make a lot of money and don't have a lot of time to go to meetings, do research and present the needed evidence to influence the code editting.
So, how do we get involved so we can present the concerns that will influence the committees? I suppose one other way is in writing as many technical questions to the committees as possible to make them clarify things they do have in place. But somehow we need our own influence on those committees. We seem to be more concerned about it than a lot of them are.
It is not necessarily the level of intellegence, it is how it is applied. Are the right questions being asked? Is the right research being done? Is there too much pressure being applied for personal agendas that may require some serious stand taking and even calling people out officially with some kind of reprimands?
I don't necessarily want you to reply to those questions, but how do we deal with it?
My job just ended for today so I am headed back up the hill. Be a couple hours before I can check this again.
Have a Great Day, Brent
I'll say one more thing about this tonight too.
Brent... While I can't speak to compliance with authority I can say this:
With the power supplies I currently own.... Axcess, Invision, 350P, Fronius, Powerwave with 10M feeders....
I am confident that the WPS's I create will produce pulsed spray transfer with no fear of falling out of that mode..... They have to be written thoughtfully and with specific controls on everything (especially WFS).
But if you put the limits in place, explain how they work, and demonstrate, I think the current generation of GMAWP power supplies can perform VERY consistantly.
Having said that.... I wouldn't use GMAWP for D1.1 work anyhow.... D1.6 yes D1.3 Yes D1.9 Yes D1.2 You bet.
If I want to weld plain carbon steel that is 1/8" or thicker in all positions I would be a moron to choose GMAWP when FCAW will outperform it by at the very least 15 inches of weld per minute! And I don't need a $15,000 power supply to do it.
Jeremiah....... Let's get down to it.... Why are we talking about GMAWP for D1.1 work anyhow... What benefit do your clients think they are going to get......? This means more than any of the above babble
Sheesh... I should have asked this in my first post..... Forgive me, it's a new semester and I'm really under pressure and obviously not thinking straight.
I can run .045 E71T-1 vertical up @ 400 ipm with 100% CO2 and 450 with 75/25 Stringers or weaves.
GMAWP will run Vert up with solid wire or metal core at about 200 ipm maybe a little faster, anything more will be trouble in most cases. Go ahead and try to stack vertical stringers with GMAWP
Flat or horizontal fillets? Why would we pulse? What advantage does this have over traditional spray when we are working with plain carbon steels?
I can't imagine heat input would be a major issue with D1.1 work, as the mechanicals with most prequalified base metals are not going to be that sensitive are they?
Automation is another matter however... If your doing GMAWP robots than maybe... but that rarely falls under D1.1
Thanks Lawrence. Those last three posts really got to the main point though I didn't state it either. I was just going with the OP question and trying to find out the justification for acceptance to D1.1. But, you are absolutely correct, why are we even asking this? What would be the point? Maybe with thinner materials and a wide gap. But, then it wouldn't be to code anyway. Every application I can think of is correctable in some other way or would be out of code compliance.
Thanks to both you and Al for your answers and patience with my persistence on this. I still have reservations as far as the direct answer to the OP. But I understand where you are coming from.
Have a Great Day, Brent
Regarding why anyone would want to use GMAW-P for D1.1 work: Smoke in the shop is what comes to mind. Companies that are fabricating in the same area as other operations such as forming, machining, etc. are not happy when the welders break out the FCAW and envelop the entire shop in a thick cloud of smoke. That might be an acceptable condition in an unheated heavy structural steel or bridge shop, but other industries will be very resistant to living with the smoke filled air.
I would not normally recommend GMAW-P for D1.2 work. I have a number of shops welding aluminum in all positions using the spray transfer mode without problems, but they are not working with sheet metal.
It is a matter of application, preferences and what the welders are used to working with.
As for serving on an AWS or ASME committee, Brent is on point regarding the expense associated with volunteering the time and money needed to pay for travel, meals, and time away from the workplace. You can't make money while attending the meetings. Financial considerations cause many qualified individuals to limit the time they spend serving on committees. Unlike our professional politicians in Washington, people serving on AWS or ASME committees don’t get paid by AWS or ASME.
Best regards - Al
I don't think that D1.1 has the same extreme impact test requirements that some of the special proprietary oil company offshore drilling rig specs might have.
That said, some of the junk grade carbon steels would be the first to fail impacts and mostly with higher heat inputs. This can be overcome by selecting a better material. But this would be for PQR's too.
I think pulsed spray would have lower heat input than spray which would improve impacts therefore I would conclude that LOF would be the main possible concern.
Sorry if I have digressed....
OB
WOW. I just got home from work and checked this post. WOW. Um....this turned out to be a bigger discussion than I thought it would be. Here's the deal. I am dealing with a shop in Menominee Falls that works with 1/8" to 3/8" structural carbon steel. They are a 100% GMAW shop, some spray some short arc. They want to qualify their welders in 3 and 4G positions to D1.1. When I told them that GMAW-S is not pre-qualified they asked if pulse was. I told them I never dealt with pulse qualifications but I would get back to them. After I couldn't find it in the code I asked on here. Little did I know......
We are almost as booked as you are down south. I have NEVER seen a need for welders and welding instruction like there is right now! We haven't gone to full Saturdays yet, but I feel it coming soon. Hang in there Larry! It's a great time to be a welder! HA!
Just a side note here. Had two different contractors on the same project. Compressor station. Contractor A submitted procedures for short arc roots - Fill/cap with spray. Contractor B submitted procedures for short arc root - pulsed spray fill/cap. All wall thicknesses were 3/4 to 1/2 inch. Rolling of all production joints. Contractor A had two repairs in 1204 welds. Contractor B had a 3.4 % repair rate that at times in production exceeded 5 %. Their repairs were very costly since almost all were in the hot (or first fill) pass. Asked contratcor B if they ever used standard spray transfer. Answer - No. Switched to pulse from Fluxcore.
Yes, both had SAW capabilities. Tied up on other projects.
Our metal building company as do many others use Pulse machines for D1.1 work. They are used for the less spatter produced as well as higher deposition rates compared to non-pulse. We typical only weld flat/horizontal so the machines work well for us since we weld materials with a wide range of thicknesses.
I do know that the CWB does not accept pulse procedures as prequalified.
Ben
This is exactly what I don't get.
Traditional spray transfer (with even the smallest amount of quality control) produces Zero Spatter.
Traditional spray has lower deposition than GMAWP? I don't see how that is possible as GMAWP is a lower (more controled current output)
It reminds me of 25 years ago when one of the gas manufacturers came out with "stargon" the 3 part shield gas that supposidly would make "spatter free welds"
So we pay more because a salesman came in and ran spatter free beads one time.
Not banging on you personally... I doubt you are the company decinsion maker BMS..... I just don't see it.
I know rehashing this post is like digging up the dead but after doing research has GMAW-P been addressed as prequalified or something different? I have yet to come up with anything concrete on this subject. Not seen in the 2015 D1.1. Any help would be greatly appreciated.
Regards,
Brian
Hello Brian, I don't believe that you will see any pre-qualified's on GMAW-P, main reason being that everyone (meaning the different welding power source/system manufacturers) utilize different and often proprietary parameters. It would likely be impossible to call out the control parameters accurately for inclusion in a prequalified document. I look forward to the responses of those much more knowledgeable than I, as I am sure that they will chime in here soon. Good luck and best regards, Allan
There you go inserting common sense again.... the nerve of some people...
Wheels turn slowly.
The Canadian Welding Bureau designated GMAWP as a prequalified process in its 2013 revision of CSA W59. (N.2.6). This has zero bearing on D1.1 but may speak to a trend as the wheels slowly turn.
D1.1 does NOT prohibit pulsed spray transfer.
Therefore in my opinion, a GMAW arc is considered spray transfer, and thus prequalified if:
1. If the welding arc is open (no short circuits)
2. If the amperage voltage relationship is above the spray transition value
3. The droplets detached from the electrode wire are smaller than the diameter of the filler wire.
4. The arc has the characteristics of a constant voltage delivery
Clearly my opinion flies in the face of other esteemed members of the forum, and has evolved in the last decade as power supplies have matured in technology, consistency and power delivery. If you look back far enough I'm pretty sure you will find me making arguments on the other side of this issue. (flip/flop? sell out? )
Allan points out the fact that GMAWP waveforms are proprietary, I'll add that most are also rather complex, consisting of layers of current/voltage and sometimes CC/CV output that often are blended at very high frequency. Nonetheless.. All the GMAWP power supplies on the market today that I know of meet the criteria (1-4) mentioned above and have the ability to record average current and voltage over the length of a weld.
Having said all of that... Why use GMAWP on D1.1 structural steel work? What is the advantage to using a power supply that costs 2X more than a typical power supply?
If you are producing semi-automatic (manual) fillets that are sized 1/4" and above or CJP joints with bevel prep of any kind, I see zero benefit from GMAWP. It will not go noticeably faster as far as deposition. (Automated/Robotic is another conversation entirely)
Brian, I think the prime question is this: What is your motivation behind using GMAWP for your D1.1 production work?
If your production needs (especially high volume manufacturing) would benefit from GMAWP, than the PQR is money well spent if you are compelled to spend it. There are some valid production advantages to GMAWP in D1.1 work... I'm just not letting the cat out of the bag for my own proprietary reasons :)
My only motivation for the question is how to deal with the situation when it comes up. I somehow foresee this becoming more and more of an issue when a fabricator wants to qualify it for whatever reason. To me it is like sitting on a spiked fence lol. With all the variations possible such as cc/cv, amps/volts fluctuating more than the allowable, etc. Also the robotic aspect of it I have never dealt with before.
Brian
I have not looked through all of the previous posts however.
If all of the provisions of clause 3 are met, pulsed spray transfer is prequalified.
However I STRONGLY suggest you verify by testing that the parameters you would like to use are suitable for the application. Though Spray Pulsed does not Short Circuit, it is possible to adjust the parameters where heat input is very low and may not be suitable for all conditions.
The commentary is D1.1 mentions a "....long record of proven satisfactory performance ." Which is something worth considerationn. Because of the wide range of variables that can affect pulsed transfer mode, I would suggest a few tests to make sure welders are clearly provided parameters that are suitable for the applications.
This is of course an opinion based upon limited experience. GMAW Pulsed is not the magic process that always works well. I am pretty sure with the right conditions, I can weld with parameters that achieve the same fusion related discontinuities associated to short circuit and be fully "legal".
Have a great day
Gerald
This is an old post, but a subject that has come up again and again.
The D1 committee has come up with an actual, formal, written interpretation on "wave form power supplies" and "GMAWP"
It does not answer all the questions, but it speaks to many of them.
https://s3.amazonaws.com/tech-www.aws.org/interps/D1.1-15-I01.pdfIt's also funny that my opinion has 'evolved' regarding GMAWP and prequalification and even application in a D1.1 style working environment.
GMAWP can do much more than it could in the 90's for sure :)
Thank you Lawerence. They covered a lot with that set of questions and the answers.
Brent
Topic American Welding Society Services / Certifications / Is GMAW Pulsed Spray prequalified for D1.1?
