Termination of Welds Near Edges Subject to Tension

[humanengr]

AWS Fig 2.6 requires welds near edges subject to tension to terminate min. weld size away from edge
(sketch attached)
Can anyone shed some light on specifically why this is required?
Since Fig. 2.6 indicates either member in tension I'm thinking it has to do with
stress concentrations in the base metal near the edges, rather than a weld issue.
You comments would be appreciated.

 

[humanengr]

That is AWS D1.1

 

[sbisteel]

Welding near (or across) the edge of a tension member like that can form a notch, which can initiate crack propagation under tensile loading.

 

[humanengr]

Thank you sbisteel. That's what I suspected, some kind of cracking issue near the edge. I appreciate your response and confirmation. I also posted this in the Structural Forum, in addition to the welding forum.

 

[BUGGAR]

Thank you humanengr for this post. You bring up one of the many little details I have a hard time remembering. I try to remember to tail a note like, "hold weld back from edge" or just specify a length. Sometimes you just have to draw a little weld hatch on the part; that seems to work best but looks bad. What does everybody else do? Just rely on AWS?

 

[gtaw]

The hold back is intended to eliminate the notch associated with an unfilled crater at the free edge of the member loaded in tension. The requirements is relatively new in D1.1. The commentary mentions it is good practice to initiate the arc toward the free edge welding toward the end of the lapped member. Again, it is the notch associated with weld terminations in the member carrying the tensile load that is of concern.

Best regards - Al

 

[Tmoose]

I think Some quasi official truck chassis modification specs call for the weld to wrap around brackets and things subject to fatigue loading (potential bending loads maybe?) . I have to say, most, maybe all, of the cracked lawnmower housings, motorcycle exhausts etc I've seen all had crackers initiating from the end of unwrapped welds on brackets. Although the basic designs usually have crappy load paths with members welded perpendicular to the middle of panels .