Welding with different Codes 5

[21121956]

Hello everybody:

Here goes my query:

John is qualified by ASME Section IX to weld in 6G (enabling him to weld in ALL positions). He is currently welding a penstock in a hydroelectric project.

Peter is qualified by AWS D1.1 and is currently welding a radial (Tainter) gate at the same hydro project.

Suppose Peter was absent from work, but the work on the gate should not be stopped. Can John continue the welding work on the Tainter gate even without being AWS cerified?

Thanks in advance for your comments.

El que no puede andar, se sienta.

 

[ATSE]

Good questions. What does the Project Specifications (contract documents) say about welder qualification?
As a structural engineer most familiar with D1.1 and only marginally familiar with ASME IX, ASME appears to be more stringent for welder qualification and weld acceptance criteria in every respect.
So if I got that formal RFI, I would answer Yes, John is more than qualified to weld D1.1 work. But some of my fellow "by the book" engineers working on public works projects would answer No.
If you have a Tainter gate on a hydro project in the US, there is probably some chance that FERC and several other gov't engineers and regulators are involved. So you might have an uphill battle, unless you are willing to wage a small war of reason (reason rarely wins).
Quoting Mary Shafer: "Insisting on perfect safety is for people who don't have the balls to live in the real world." Gov't engineers usually don't have this mentality. Instead, usually "by the book."
Good luck and tell us how it goes.

 

[gtaw]

I would challenge you on the acceptance criteria for the welder qualifications. The visual acceptance criteria is very sparse in Section IX, while it is pretty exacting based on D1.1.

overlap - not addressed by Section IX
face reinforcement - not addressed by Section IX
undercut - not addressed by Section IX
unfilled craters - not addressed by Section IX

With regards to guided bend test results:
ASME - no open defects greater than 1/8-inch, with no limits as to the sum of the lengths of the open discontinuities
AWS D1.1 - no open defects greater than 1/8-inch and the sum of all open discontinuities can't exceed 3/8-inch

So, yes, I challenge your comparison of Section IX to AWS D1.1

Just saying -

Best regards - Al

 

[weldstan]

It all depends on the wording in the law and contract. For many construction projects that I have worked, the majority permitted welders qualified to ASME IX to weld structural components but not always. Welders qualified to AWS were not permitted to weld on ASME Code items.

 

[21121956]

Hello everybody:

Thank you all for your comments.

John is welding the Tainter gate as a result of the Engineers's (Owner's Representative) decision.

Given the integration of John in the welding works of that gate, it only remains to await the results of the non-destructive welding tests.

So far, John's welds have passed Ultrasound and Penetrating Dye tests. Peter is expected to resume work on the gate in a couple of weeks.

Once again, thanks for your inputs.

El que no puede andar, se sienta.

 

[ATSE]

GTAW,
Well, nice detailed response for welder qualification. I was about to say, "Challenge Accepted" but now I'm wavering.
Give me a minute to recover for a solid left hook to the head, and I will try to muster up a counter punch.

 

[DVWE]

I will try to muster up a counter punch.

I wouldn’t.

The devil is in the details; she also wears prada.

 

[ATSE]

GTAW -
I take no exception to your comments on the specific welder qualification requirements.
Comparing and evaluating welders based on how stringent their respective qualification test was (possibly 10 or 20 years in the past) is akin to comparing the acumen of engineers based on how difficult their state PE exam was (possibly 10 or 20 years in the past).
i.e. When I took my state SE, the passing rate was around 20% most years, so that makes me a better engineer than those in the neighboring state with passing rates closer to 50%.
For the scenario presented, welder experience should be evaluated in conjunction with original test requirements.

Here is my pragmatic view: For most industrial and municipal projects I work on, AWS welders are mostly welding fillet welds and PJPs (CJP in the field is rare, by design) on very forgiving steels, while the ASME welders are usually welding small diameter process pipe (and sometimes pressure vessels), with more frequent and stringent NDT.

So on paper, while the AWS welder qualification test (one time event) may be more defined and rigorous in some aspects vs ASME IX, I think the welder that is routinely doing 5G welding on medium to small diameter pipe with associated testing is qualified "in practice" to do fillet and PJP welds on plate.
The inspection and acceptance criteria would of course not be relaxed. For good measure, you could make it more stringent until Peter gets back.

If you have the patience to continue, I'm listening.

 

[gtaw]

Let me open by saying I’ve been testing welders for, well, let's just say a long time. I also welded for over twenty years in the shop and in the field on both structural steel and pipe.

The skill set need to weld structural steel differs from that needed to weld pipe. Many of the welders experienced welding pipe struggle to pass the structural qualification and structural welders struggle to pass a pipe test. Pipe welders tend to weld with lower amperage simply because the wall thickness of the pipe is relatively thin. The structural welder is welding members that are much thicker and require higher amperage. Pipe welders, limiting the conversation to shielded metal arc welding on ferrous metal, often weld open root pipe joints where the electrode is typically a cellulose based flux covered electrode at low amperage using a whip technique. The whip technique isn't recommended when welding structural steel using a low hydrogen electrode.

I've tested many welders transitioning from pipe to structural and vice versa. Both struggles to make the transition because different electrode types are used, amperage ranges are different, and the techniques are different. It isn't to say it is impossible, but it is surprising how many welders can't make the transition without practice.

You mention that most of the structural welding consists of fillet welds as if the fillet weld isn't that difficult to deposit successfully. Over the last twenty years or so I've always included a requirement that the welders pass a "simple" T-fillet break test before welding on my projects. The failure rate is surprisingly high and most welders fail due to incomplete fusion in the root. If one was to "believe" the codes, a welder qualified on a groove test is automatically qualified to weld fillets, yet many welders cannot pass the fillet weld test without coaching and practice. My experience has been the pipe welders struggle more than the structural welder because the pipe welder is more accustom to welding with low amperage and using stringers. When the pipe welder takes the plate test with backing, a typical problem is securing fusion in the corners of the root between the groove face and the backing. Once again, the problem is typically using low current and using a slight weave in the root.

With regards to the simple fillet weld, I asked my professor while I was a student taking my structural design courses, why the size of the fillet welds most often specified were ¼ and 5/16-inch? His response was because that size is relatively easy to deposit with large diameter SMAW electrodes. That statement is perfectly logical and true. As I worked my way through college I worked as a welder in a fabrication shop and we welded with 3/16 and ¼-inch diameter electrodes day in and day out. That is no longer the case. Flux cored arc welding and gas metal arc welding are the welding processes of choice in the modern fabrication shop. The electrode diameters are much smaller and some manipulation is required to deposit a ¼ or 5/16-inch fillet weld in a single pass. The fact that the welder must manipulate the electrode is the problem. If I see the welder making circular movements with the electrode, there is a high probability the welds are not fused in the root. The same is true in the field if the welder is trying to deposit large fillet welds in a single pass. By the way, if the welder isn’t using low hydrogen electrodes, there are minimum sized fillet welds that must be deposited as single pass weld per the AWS structural welding code/steel. Once again, it is all about the technique used by the welder to make those large single pass fillet welds and using sufficient welding current.

The bottom line is the Engineer (the Owner’s representative) has the authority to allow welders qualified to a different welding standard to weld structural steel without being requalified. You are correct when you mentioned that a lot of engineers do allow welders qualified to ASME Section IX to weld on structural work. It makes my job as an inspector more challenging, but oh so much more profitable.

If you have any doubts, simply have your welder take a simple T-fillet break test. It is a single pass 5/16-inch fillet weld on one side of a T-joint consisting of ½ x 4 x 8-inch plate. If the welder knows what he’s doing, it is a 15-minute test. If the welder can’t pass that simple test, do you really want him or her to be welding all those fillet welds on your project? Remember, as mentioned, structural welds rarely get more than a visual examination. I don’t know many people, other than Clark Kent, that can see whether there is proper fusion in the root of the fillet weld.

I look at it this way; I wouldn't go to a brain surgeon to get a colonoscopy and I wouldn't go to a proctologist for brain surgery. Both are doctors, but their areas of specialization are at different ends of the spectrum.


Best regards - Al

 

[DekDee]

Al,
Agree 100% on your comments regarding the fillet break test.
Cheers,
Shane

 

[ATSE]

Al - that was worth 3 stars, but I could only give one. The simple fillet weld pre-production test might soon find its way into my Div 5 spec sections.
Thanks for taking the time to articulate your experience.

 

[kingnero]

Another "I concur" with GTAW

This is even so common or widespread, that some (ISO) standards do not allow butt weld qualification holders to weld FW's under that qualification - FW needs to be separately qualified.

 

[gtaw]

Someday, maybe I'll still be alive to see it, the more progressive welding standards here in the US might see the light and require a separate performance test for fillet welds.

Best regards - Al