American Welding Society Forum
I'm having a very difficult time qualifying a PQR to D1.2.
2" diameter round tubing
1/8" wall thickness
1/8" root opening with backing
Average volt 17
Average amperage 170
Test passes tensile and face bends. The root bends from the top of the pipe are good. The root bends from the bottom of the pipe are failing. We keep getting cracking in the weld... not from lack of fusion.
Using a wrap around bend jig. 2 1/16" diameter bend. Specimens are 3/4" in width as per note 2 in figure 3.12.
Any thoughts? I'm at a loss.
Anyone? I've poured over everything I can get my hands on. I've had no problems in the past qualifying the same scenario with plates. This is the first time I am trying to do these bend tests in M23 round tubing. The root bends continue to crack.
I think I resolved it... if anyone cares... it seems there was a flaw in our bending jig. The roller was getting caught on the curved edges of pipe and not rolling, rather dragging and pulling the specimen. This wasn't happening on the face bends because those are one the opposite side of the curve and not causing friction.
Nice to know it, thanks for the feedback! Have you tested again? Positive results?
Sorry I cant help you on this subject, but your experience can help others!
Yes... after adjusting the roller on the bending jig so that it wouldn't get jammed up, the root bends had no cracking
Glad you figured it out. I have had my fair share of issues with 6061 as of late...
Sorry I did not see this until today.
You could have ran it through RT for qualification worst case scenario. :)
They have to perform the bend test for procedure qualification.
Unless it's a fillet PQR ?!?!?!?!!!
I believe a close read of D1.2 will reveal the procedure needs to be qualified to verify the mechanical properties can be met. This is aluminum; almost a metal.
Negatory good buddy... No tensiles required for a D1.2 fillet WPS. :(
This one I confronted the D1.2 committee face to face and Frank Armao himself explained.
However they also scoff at any engineer that designs a weldment without knowledge of the mechanicals.... Sort of ironic eh?
I would hold out until an official interpretation was handed down on that.
The fillet weld qualification only provides evidence the weld contains no unacceptable defects such as incomplete fusion, porosity, unacceptable contours, etc. The fillet macroetch or break test provides no information with regards to the strength or other mechanical properties of the weld.
The mechanical properties of the combination of filler metal and base metal can only be determined by using destructive mechanical tests such as the reduced section tensile test.
A welding engineer, welding inspector, or welding consultant has to keep in mind that it is their responsibility to ensure their activities protect the interests and safety of the public and meet the minimum requirements of the applicable welding standard. I would say it is irresponsible for a professional to proceed with production without verifying the WPS has the demonstrated ability to produce acceptable mechanical properties.
I read and understand clause 3.12 to require the qualification effort to include both strength and degree of soundness determinations. To quote, "The WPS qualification tests required in Part C are devised to determine the strength and degree of soundness of welds made by a specific WPS." I take special notice that the clause includes the word "and" between the words "strength" and the words "and degree of soundness". It is the opening paragraph on the subject of WPS qualification and applies equally to all weld types.
Clause 3.14 directs the reader's attention to Table 3.1. It begins with; "Change greater than the limits set in Table 3.1 shall be considered essential changes in a WPS and shall require qualification of the altered WPS. Table 3.1 requires a groove weld. No mention of a fillet weld is noted.
I spoke with the chair of the D1 committee several years ago on this subject as it related to the structural welding codes. His position was any welding engineer that is worth his salt knows that one must demonstrate the mechanical properties are met before qualifying a WPS for fillet welds.
The structural welding codes, like any welding code or standard, are not perfect. I think one must have a reasonable understanding of the purpose of qualifying WPS and the means employed to qualify a WPS. The fact that a weld is uniform and has a reasonable profile offers no assurance the weld has the necessary mechanical properties to provide useful service. The mechanical properties can only be established by mechanical testing.
The qualification of a fillet weld fails to establish the mechanical properties that can be expected with a specific combination of base metal and filler metal. One can produce a perfectly fine looking weld that fails miserably when tested for tensile strength or when attempting to pass a guided bend test. After all, once again, we are talking about aluminum, almost a metal.
Best regards - Al
Your argument "should" win the day.
Sometimes I cant help poking the bear :)
It is only when we poke the bear that we find out how fast we can run. That's why I always hunt with a fellow on crutches. I know I cannot out run the bear, but I only have to run faster than the fellow on crutches!
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