Fillet weld WPS and PQR

Date 03-25-2015 16:04

Wow jsd, great question.

The few PQR's I have dealt with were always done in a bevel groove. Haven't dealt with them using only fillets. Which leads to my first question, why are you qualifying with fillets instead of grooves which can then be used to write a WPS for fillets?

My second comment would be, more than likely your welder is already qualified to fillets either by a fillet break test or because they are groove qualified. So, the only advantage to this particular test would be that they are actually qualified to the joint, material, filler, or whatever that needed special qualification because it isn't pre-qualified. That being said, the start/stop portion is somewhat a mute point if you see what I mean. Only if a customer actually requests that all welders on their project test to the PQR to prove qualification on their exact application would it be a necessary test for the first welder as well as all others to take and pass. Even then, the start/stop may not be an issue. Just proving they can weld on the customer's project. Not truly qualifying the welder to D1.1 Fillet Weld standards.

Now, I am not looking at the sections you mentioned or others right now so this is an off the hip personal opinion which is worth even less than what you paid for it.

He Is In Control, Have a Great Day, Brent

By jsdwelder (***)

Date 03-25-2015 16:24

Thank You Brent. The welder in question is not currently certified/qualified at all. This is a company who wants their welder qualified to the AWS D1.1. They know enough about the code to know that a fillet weld PQR can be used to gain a fillet weld performance cert as well but that's about it. The only weld on this particular piece is a small fillet weld. No grooves on the weldment. I might tend to agree with you on using a groove weld for qualification to cover the fillet however they really didn't want the expense and time it would take to perform all that is needed for a groove PQR (NDT, tensile's, bends, etc..) just to do this one fillet weld per unit. Thanks

By 803056

Date 03-25-2015 17:45

A groove weld must be qualified to establish the minimum requirements for the mechanical properties can be met. The PQR that records the parameters and test results for the fillet weld only establishes acceptable parameters for the largest single pass fillet weld and the smallest multiple pass fillet weld. The fillet welds do does not establish the mechanical properties.

One must read very carefully to decipher the requirements of D1.1. Some of the other structural welding codes are a lot clearer regarding the intent and much easier to understand.

I generally qualify the fillet welds to establish the welding parameters and then use those parameters to demonstrate the requirements for the mechanical properties can be met.

Regarding welder qualification, I always require the welders to pass the fillet break test regardless of previous qualification using a groove test. The failure rate on the fillet break test is surprisingly high!

The code lists the minimum requirements that must be met, but one must read the provisions very carefully as if they were a Philadelphia lawyer to mine the requirements and to properly qualify the WPS for production. The company that only meets the minimum requirements (or what they perceive as the minimum requirements) can be in for a rude awakening when the lawyers do "come a knocking, knocking on their cabin door."

Best regards - Al

By jsdwelder (***)

Date 03-25-2015 18:15

Al,
What is your take on why the failure rate for fillet weld break tests are so high? In our field it is generally accepted that a groove weld is the more difficult of the two (Although I've seen many a certified welder who really made me question their ability to make any weld)

By welderbrent (*****)

Date 03-25-2015 18:35

I know, I'm not Al, BUT, this is an internet forum and you can't see me to prove that.

There has been discussion here on that before and in much depth. There are many possibilities.

One of them would be that there is a large difference between welding to a backing bar in a root opening of about 3/8" with a groove angle of 90° and welding in a T-joint with no root opening so that the 90° corner is more difficult to get penetration down to if not beyond the joint. More material in the area to absorb heat and interfere with the weld pool digging in where it needs to be.

Many welders that can pass the groove test cannot pass the fillet test. Try it sometime.

He Is In Control, Have a Great Day, Brent

By jsdwelder (***)

Date 03-25-2015 18:55

Interesting. I would assume, and maybe I shouldn't as we all know how that goes, that most of the failures would be due to a lack of penetration to the root? I will try this with some students

By welderbrent (*****)

Date 03-25-2015 19:22 Edited 03-25-2015 19:32

Yes, sorry, I said "joint". The ROOT is where you must get penetration AND fusion to if not beyond. That is why you shine up the fillet weld test by sanding and do a macro-etch. It will show very clearly if the penetration is to and/or beyond the root. Many people have a hard time determining such in the visual of the bend.

The angle is the same but not the way they come together. The penetration from the edge of a knife edge bevel to a backing bar with a 3/8" opening to be able to maneuver the arc and weld pool compared to that in a T-joint where the full thickness comes together with a tight space at the 'root' of the joint is quite different.

Brent

By jsdwelder (***)

Date 03-26-2015 13:43

Not to slight anyone else but I don't think I've ever read one of Al's posts and not learned something! Thank You for your input.

By 803056

Date 03-27-2015 02:39 Edited 03-27-2015 02:44

Thanks for the compliment.

I have a question for my good friend Brent. What is this 3/8 inch root that is referring to? The figures in my 2010 edition of D1.1 (Clause 4) don't include any with a 3/8 inch root opening. I might be missing something here and I don't want to comment with one foot in my mouth and the other heading in the same direction.

I wrote an article on the subject a little more than a year ago for Inspection Trends. You can find the article in Past Issues of IT if you visit the web site and if they finally have the site up and running properly. Boiled down; I suspect the problem is that in the days when the power supplies were belt driven hamster wheels and the welders used baseball sized SMAW electrodes, a single pass 5/16 inch fillet weld wasn't that difficult. However, times have changed, the power supplies require a degree in electronic wizardry and small diameter solid or tubular electrode is used by many contractors. The welder must have proper training and time to develop the proper technique to deposit a proper single pass 5/16 inch fillet weld.

The majority of the welders I've tested fail because they do not achieve fusion to the root of the T-joint. The incomplete fusion is obvious when the center 6 inches of the weld is loaded to failure. A couple of other problems are overlap and undercut when welding in the 2F position. 4F position; nearly impossible for most welders to pass when using the GMAW-S or FCAW processes. That's right, GMAW-S, keep in mind the process is not prequalified for any position, so the WPS has to be qualified for the positions used in production (groove test for mechanicals and fillets for the proper parameters).

My recommendation is to use 1/2 x 8 inch bar saw cut to the proper length so that the saw cut edge of the butting member seats tightly against the nonbutting member. It affords the welder the best opportunity to pass the test without cheating.

Best regards - Al

By welderbrent (*****)

Date 03-27-2015 16:18

Okay, I see a couple of mistakes in my comment as I was trying to make a comparison point and did not pay close enough attention to my details. While 3/8" root openings are common in production, they are not for performance quals which is the current context.

I also used 90° groove angle when it should have been 45°, 22.5° on each bevel. Wider angles are permissible in production but not performance. Single bevels, which I am dealing with a lot right now, can be 45° + 10° = 55°, but that does not equal a 90° for a V-groove for a performance qualification which is 45° period per Clause 4.

My point being though how the steels come together and absorb the 'heat' of the arc and weld pool so that it is more difficult to get good fusion to the root in a T-joint with fillet welds than it is in a groove joint with backing and welding with the applicable groove weld.

I see welders using processes with the electrode 'pointed' in the wrong direction and/or just the way they are allowing the weld pool to flow thus allowing the weld pool to be between the arc and the root so that good penetration is not achieved. This will also, depending upon process and other factors, allow slag entrapment as well as lack of fusion at the root which makes penetration even more difficult.

I agree with Al's analysis of the variation in process power sources as well. When I used the old Lincoln 'jet engine' 440 3 phase welders and the old portables with the large generators, if you couldn't lay a good weld regardless of fillet or groove you really had a problem. But, with the power sources today, it takes many welders some hard work, lots of practice, and several failures before they get a technique they are consistently successful with.

Would not have been your foot in your mouth, my wife is still working at getting the come-a-long positioned to extract my two feet from mine.

Brent

By 803056

Date 03-28-2015 00:08

OK, you cleared that up for me. Thank you Brent.

Best regards from Miami!

Al