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Size of Flare Bevel Welds

Size of Flare Bevel Welds

Size of Flare Bevel Welds

Hello All,

I have a deceptively simple question.

Suppose you have old drawing for a welding steel frame which includes flare bevel welds (single side).  No weld size or prep. size specified.   

The frame was fully analyzed via FEA assuming full connections (ie no special modeling for welds or hand calcs.), tested to static and crush strength, passed no problems.   Actual welds generally "fill the joint completely", not CJP but typicaly show melt through. CJP is NOT specified in the tail.

If asked to specify the weld size as function of T, the thickness of the thinnest part, what should that be based on the above?


RE: Size of Flare Bevel Welds

Based on your information, I would refer you to AWS D1.1 Structural Welding Code - Steel for information on flare-bevel-groove weld size. I believe the section titled "Design of Welded Connections" contains the requirements for prequalified Flare-bevel-groove weld joints. I have a 1994 copy of the AWS D1.1, and the information presented in Figure 2.5 identified the weld size as 5/8T1 (the thickness of the member making the corner joint).

RE: Size of Flare Bevel Welds


Thanks for your input.

My understanding of the code is that 5/8 T is the EFECTIVE SIZE, i.e. the throat used for calculation purposes, and in order to get that effective size, the joint must be filled flush per D1.1 - 1994 Filling flush would mean fill the joint to the degree possible.

My concern is new suppliers trying to bulid this will under fill, thinking the bead need only have a 5/8 T leg (thickness).  That is not same as throat in this case.

I feel the code is not clear here.  

Yours or anyone else's thoughts?

RE: Size of Flare Bevel Welds

You can specify to have the weld joint filled flush as part of a process step or QC requirement.

RE: Size of Flare Bevel Welds

As a follow-up, the AISC also has some excellent information as to the design requirements for throat size for flare-bevel-welds. Check out the web site below;


Under research, there is a paper on calculation of effective throat size for flare-bevel welds.
Some interesting background and information

RE: Size of Flare Bevel Welds

Chapter 2 of D1.1 is design, so it deals with theoretical issues.  For control over what the fabricators actually do, you need Chapter 5 on fabrication.  In particular, Figure 5.4 lists underfill as an unacceptable profile.  The referring code section is 5.24 (in D1.1-2004).  Don't let them tell you that a flare bevel weld doesn't count as a groove weld.


RE: Size of Flare Bevel Welds


Excellent link!  Thanks so very much.  In that paper you can see what I am trying to avoid. Flare bevels that have throat depths of t or slightly greater is what is needed in my case. The "bridged" shaped welding is what I am trying to avoid.  

Why is this so complicated?  Well, we have two new suppliers working in two countries working with design drawings from a third supplier (OEM) from a third country.  All are required to work to D1.1. The original OEM "filled" the grooves to the best of my knowledge and conducted full scale plastic testing to qualify the design. As I said if 5/8T goes into the symbol, I am concerned some one will assume a smaller weld that OEM is OK (quicker, cheaper etc.).  They have several THOUSAND of these welds to make in the next 5 years.

HgTX  Thank you very much as well. I will hold my ground on this and we'll hold them to D1.1.


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