Butt Weld Strength

[wailunwu]

Hi

ASME VIII Div 1, para UW-18 (d), Specified Fillet weld strength . Is there a similar paragraph to evaluate the strength of butt weld? How would I go about evaluating (full penetration) butt weld allowable load/ strength?

Thanks,
Alan

 

[marty007]

In ASME, butt welds are assumed to be as strong as the parent material. That said, you have to derate the strength of the parent material based on the level of radiography applied to the vessel joints (full/spot/none), and the style of welding used. This all gets translated into a weld joint efficiency (E), used to size the thickness of the parent material.

Hope that helps...

 

[metengr]

First, review UW-15 in ASME Section VIII, Div 1 welded connections. In determining the strength of welded connections, for groove welds in tension, the allowable stress value for the weld is 74% of the allowable stress for the base metal. Read more to better understand how this applies to your case.

 

[wailunwu]

thank you!

 

[c8829]

UW-18 (c) Figures UW-13.1 and UW-13.2 show several construction details that are not permissible.
while UW-13.2 (g) is fillet weld..how??

 

[davefitz]

On the same topic, I assume you are primarily interested in the axial (longitudinal) strength of the butt weld- I do not find in sect VIII div 1 a discussion on weld creep strength reduction factor. If the pipe is supporting a primary gravity load in the longitudinal direction and it is operating above 800 F, then the creep strength of the butt weld's HAZ should be considered in determining the final weld strength reduction factor.

"Whom the gods would destroy, they first make mad "

 

[wailunwu]

@c8829
Code is referring to Fig UW-13.2 (o) (p) (q)