Inspection Trends Article

Date 01-28-2013 17:42

Not that I recollect. You may be thinking of ASME Section IX when the test material is 1/2 inch or less.

I don't have D1.1 or Section IX in front of me, so you might want to check for yourself.

Best regards - Al

By gastonM (**)

Date 01-28-2013 19:20

B2.1 SPECIFICATION FOR WELDING PROCEDURE AND PERFORMANCE QUALIFICATION, IS QUITE SIMILAR TO ASME IX, i don´t know, that what not first , if the egg or the hen. Any way, both standards says under 1/2" coupon thickness don´t qualifies up to 2T or 2t. May be ,that steels covered by D1.1 are not subject to lack of fusion?

How do you qualify the newisnp example, with CVN?

By 803056

Date 01-28-2013 19:44 Edited 01-28-2013 20:12

Different welding standards have different requirements.

AWS has tried to harmonize B2.1 with ASME Section IX, so similarities abound.

Qualification for CVN has additional restrictions called supplementary essential variables. Still, the limitation of 1.1 times the thickness of the test material is in ASME Section IX, not AWS D1.1.

What is this lack of fusion you speak of? Is it inherent to short circuiting transfer only? I’m just messing with you my friend. Incomplete fusion is a concern when using short circuiting transfer, but is the problem primarily due to the thickness of the base metal or simply because the process can be characterized as a low heat input process? Is the problem an issue with welder skill or is it due to process limitations?

It appears that ASME Section IX limits the thickness range qualified to 1.1 times the coupon thickness because the process is characterized as a low heat input process that is better suited to thinner materials. It makes sense that if the WPS is qualified on thin material the low heat input used may not be suitable for thicknesses much greater than that tested. However, if the test coupon is more than ½ inch thick, the heat input used is most likely sufficient to weld thicker material as well. It makes sense to me.

The AWS Structural code on the other hand usually deals with thicker material. If the procedure is qualified using 3/8 inch thick steel, the heat input is most likely sufficient for thicker materials as well. The difference between ASME Section IX and AWS D1.1 is only 1/8 inch. Not a big deal in the wonderful world of structural steel.

Incomplete fusion is an issue when welding with GMAW in the short circuiting mode of transfer. Different codes take different approaches to the problem because the committees are composed of different people having different interests, different opinions, and different experiences.

As for my opinion, when I encounter a contractor using GMAW-S, I tell my wife to book another week of vacation because the job is going to be a money maker for me. In other words, there will be problems because there will be issues relating to incomplete fusion unless the job entails working with carbon steel 1/8 inch or thinner. If the contractor is trying to weld structural aluminum with GMAW-P or GMAW-S, sell all the fabricator’s stock we own because they are going to be in bankruptcy in short order.

Will someone please explain why contractors insist on using GMAW-P to weld in the flat or horizontal positions when welding heavy structural steel or aluminum? Don’t get me wrong, I make more money when contractors do silly things, but why don’t they learn from past mistakes? Does becoming a contractor involve having defective genes, a loose wire in the cabinet, or brain trauma? In all honesty, Darwin usually comes to society’s aid and culls the weak contractors in short order. So, all is well in the long run. Those that do not learn eventually find different livelihoods.

Weld a go-cart and the boy drives it for another day. Teach the boy to weld and he terrorizes society by becoming a contractor as soon as he saves enough money to buy a pickup truck.

Al

By gastonM (**)

Date 01-29-2013 12:11

Nothing is less, than using GMAW-S, due to the extremely low productivity. but sometimes we use it, to correct excessive root separation. What if so, how do I qualify thicknesses of 1/8 "to 1/2" with CVN?. You accept a coupon of 1/8 "and a coupon of 1/4" (for example by welding A36 or SA-36), according D1.1, but not per ASME IX. Standards are standards, but in this case I do not see razonble.

Regards.

By 803056

Date 01-29-2013 22:31

Gaston, my friend, AWS D1.1 qualifies the thickness range of the WPS based on the thickness of the test coupon, not the thickness of the deposited weld metal.

D1.1 has no provisions to qualify a WPS using multiple welding processes on one test coupon. That is a major departure from how ASME Section IX qualifies a WPS. ASME Section IX permits the contractor to qualify more than one welding process and multiple thickness ranges using one test coupon. This is possible because the thickness qualified for each welding process is based on the thickness of the weld metal deposited with each respective welding process.

As I mentioned before, my opinion is worth exactly what you paid for it. In my opinion the contractor would have to qualify the WPS that utilizes multiple welding processes by multiple supporting PQRs. That is to say, if the contractor wants to deposit the root bead in the groove with GMAW-S, then there must be a PQR to support that. If the base metal to be groove welded in production is 1-inch (25.4 mm) thick, then the test plate must be at least 1/2-inch thick. If the contractor elects to weld the remaining portions of the grooved joint using FCAW, then the WPS must be supported with an additional PQR that utilized a test coupon at least 1/2-inch thick as well. The two supporting PQRs, each utilizing 1/2-inch plate, are only qualified up to the maximum of 1-inch thick. The two PQRs cannot be added together to support a WPS for production groove welds in 2-inch thick base metal.

In my opinion, it would be more efficient if two separate WPSs were qualified, each with supporting PQRs, and the two WPSs used together to accomplish the production groove weld. The GMAW-S WPS would be used to deposit the root bead (or more if needed, up to and including 1-inch max.) and the separate FCAW WPS could be used to weld the remaining portions of the grooved joint (again, up to a max. base metal thickness of 1-inch). The two individual WPSs would not support the contractor's efforts to weld a 2-inch thick grooved joint.

One must be very careful not to comingle the requirements of one welding standard with those of another. What is justified and permitted by one welding standard may not be permitted by a second welding standard. It is a fact of life that different codes, with different people formulating the requirements, each committee with different prevailing philosophies result in different code requirements.

That's my story an I'm sticking with it.

Best regards - Al

By eekpod

Date 01-31-2013 11:28

I don't see how any test coupon could pass the tensile, bend and CVN if part of it were welded with GMAW-S, Even if you are trying to qualify the procedure. I would think the tensiles and bend tests would fail wayyy before the minimum values required are achieved. just my opinion.

By 803056

Date 01-31-2013 17:48

Actually, I've qualified several procedures using GMAW-S on plate and had no trouble passing.

You just need to set the machine properly and use a welder that knows how to weld. Incomplete fusion isn't a given as long as the welder's technique is correct and he doen't fiddle with the knobs once e machine is set where it needs to be.

Al

By eekpod

Date 01-31-2013 19:13

How thick was the plate Al?

Briefly, what's the secret top setting the machine right? I thought the idea of GMAW-S was so that not too much heat goes into the material, which I correlate to not alot of fusion.

By welderbrent (*****)

Date 01-31-2013 22:13

Chris,

The problem is welders who don't really know what the process's limitations are and how to develop the amps/heat that will translate into penetration/fusion. I have qualified, more than once, for structural welding using GMAW-S. Usually on 3/8" plate test, but I did it once unlimited just to prove I could (I love a challenge, like when people are under the impression that you can't use it at all for structural). And yes, it was put through all the tests for proper qualification of a PQR not just a bend test and most definitely not just an Xray. I can make them pass Xray any time. But get them to pass bend and tensile.

Many welders can set the machine and make excellent welds on thin material, 3/16 and thinner. Some can even turn it up and do not too bad at 1/4". But few can pass a simple bend test on any thing thicker because they don't really know how to push the envelope.

Secret, knowledge is king.

Have a Great Day, Brent

By 803056

Date 02-01-2013 02:37

Chris;

We were welding 1 inch thick plates inside the containment of a nuke. We were welding in all positions, hence te need to use GMAW-S. We didn't have pulsing available at the time.

The parameters were specified with very limited ranges for WFS, V, A, and travel. Interpass was limited and monitored for each weld bead.

The procedures were qualified by testing; VT, RT, tensiles, bends, and CVN.

It was like welding with tooth paste. You had to put the metal where you wanted it. You could not let the weld pool flow and expect the heat to be sufficient to fuse. It is not a forgiving process and not something I would recommend, but the job had special considerations that precluded considering SMAW or FCAW. Snoke was te issue due to the contamination issues.

If the welders didn't weld within the ranges specified; "see you later."

Best regards - Al

By eekpod

Date 02-01-2013 11:22

Interesting, thanks to the both of you for sharing that.
I guess I thought that the note in the code (unless qualifed or whatever it says specifically) was more of a disclaimer and not meant to be actually tried. I have never had use for it but it's good to know it can be done if needed.
Thanks

By 803056

Date 02-01-2013 15:05 Edited 02-01-2013 15:07

There is very little that is prohibited by our welding standards if the contractor is willing to take the time and effort to qualify the welding procedure specification and demonstrate the WPS will produce the desired results.

In the case of D1.1, the Engineer has the authority to override code requirements and in the case of the need for qualifying the WPS or the welder, it is permissible to accept qualification to other standards such as B2.1 or even ASME Section IX (he has to prove mental competency in the latter example). In some situations the Engineer can even permit the contractor to begin welding without WPSs or welder performance qualification if the nature of the job doesn't necessitate the need (in the Engineer's judgment).

I had a job early in my career where there were five individuals making sparks and smoke upon my arrival on the project. None of them were qualified welders; three of the five had never welded before I arrived on-site. I reported back to the Engineer by telephone to inform him of the situation and that I had seen undercut that extend halfway through the column web, moment plates installed upside down and in the wrong location, blah, blah, blah. The Engineer told me to let them keep going. I told the Engineer that I was not turning in a report, that I would deny I was ever on the site, and there would be no bill submitted. He said, "You can't leave the job, I need to know what's going on!"

I responded, "What job are you talking about." I hung up and refused to work on any more of his projects. It was a personal choice I made and to this day I do not regret doing so. I would have regretted my decision to stay on the site if something catastrophic had happened and if I had played an integral part in the oversight of the work. How would I have justified allowing it to continue?

Was he wrong? The Engineer has a legal obligation to ensure the drawings and his design are followed, i.e., the intent of the design are met and the structure is safe to use. The intent of verification inspection is to provide a mechanism where by the Engineer has a representative on-site to ensure the Owner gets what the contractor has agreed to do and to ensure the Engineer the approved drawings and project specifications are followed. If the Engineer determines the work is "good enough" and signs off that his requirements were met, all is well in the world. As long as there are idiots walking on the face of the earth, there will always be a need for lawyers and courts.

I am happy to report that the laws have changed since that incident. Unfortunately it took serious events such as the collapse of the Hartford Civic Center, Le Ambiance Plaza, and the Tea Room Walkway in Kansa City, etc. to get people to realize things had to change. What happened on that project many years ago would have less likelihood of happening today because the building departments and building laws have more authority and more teeth. That being said, I remember working on a project where the engineer was from a different state. I called the State Building Official to report a couple of problems that were not being resolved by the Engineer of Record. The SBO, an architect, responded to my comments with, “Al, how many building actually fall down?” So I responded with a list of structural failures that had recently occurred in Connecticut.

“All right, all right, I get your point. I’ll make a call to see what’s going on.” He snorted.

All the discrepancies got fixed shortly thereafter. Conclusion: even the big wigs hate to be disturbed from their slumber or interrupted when they are busy reading the sports page. However, when pushed hard enough they will react. Imagine what it would be like without these public guardians protecting our safety?

Hey, Roy, what was the final outcome down in Florida on the Marlin's stadium? Roy has an interesting story to tell. I hope he reads this where ever he is. Following my friend Roy's exploits is like playing a game of "Wack a Mole", you never know where he will show up next. He always has an interesting story to tell.

Best regards - Al