Skewed T Joint Pass Size - AWS D1.1

[48v]

Hello,
I'm trying to write a prequalified WPS for AWS D1.1:2008. I have a skewed T joint as in figure 3.11(D). My concern is that I can't see how the first pass could be made without the depth being greater than the face width (as prohibited by 3.7.2 and fig 3.1.) Is it typical to ignore that provision for the first pass of this detail. Can I count the Z loss dimension against this requirement? Is there something silly I'm missing? In case it matters, the process is FCAW-G.
Thank you for any help you can offer.
--Ethan

 

[kalldan]

Thank you

 

[gtaw]

The Z-loss is the region where there is no assurance of the weld fusing to both members or whether there will be any weld present. In any event, should there be any weld metal present, it is not included in strength calculations. Most likely, there will be a void in the region identified as Z-loss. That being the case, the structural design engineer indicates the required throat dimension of the weld required to transmit the design load. The detailer has to detail the welded connection to include the Z-loss and the required throat dimension. Since the weld in question is not a fillet weld, a fillet weld symbol is not appropriate. Instead, it is better to use a reference line and arrow identifying the location of the weld with a reference in the tail directing one to a detail/sketch of the connection showing the appropriate dimensions of the weld leg, throat, and Z-loss so there is no question about the required weld size.

If one refers to AWS D1.1:2010, it will be noted that for connections where the angle between adjacent members is less than 80 degrees, the term fillet weld is not used. In cases where the dihedral angle is less than 60 degrees, the Z-loss must be considered. Essentially, there is a potential for a void to exist where a Z-loss is greater than 0.

Best regards - Al

 

[48v]

Thanks for the response gtaw. I understand how to detail the weld and calculate its throat. My concern is not the strength, just how to make the first pass without violating section 3.7.2 which says "Neither the depth nor the maximum width in the cross section of the weld metal deposited in each weld pass shall exceed the width at the surface of the weld."

I've attached a sketch of the weld I'm concerned about. On the first pass, the depth of the pass will be larger than the width at the face. In my case, z-loss is zero, so I'm assuming the weld does reach all the way to the root. Based on that, this weld appears to contradict the requirement of 3.7.2 even though it's explicitly prequalified by fig 3.11(D).

I'm not realistically that worried about centerline cracking. We're using a small first pass and haven't had any problems on production welds. I just wanted to see if others had encountered this problem, or if there was a commonly accepted interpretation of this requirement. When we need more than one pass, we can split the second layer and restore order to the universe.

Thanks for any advice.

 

[gtaw]

I don't have D1.1 handy, but I believe the requirement you are referring to is relative to a groove weld. The detail you provided is not a groove weld.

Best regards - Al