Flare bevel groove weld 3

[WARose]

In the 13th ed. of AISC, on p. 8-61, in the table they give the "Base Metal Thickness" T₁ for the SMAW process as 3/16 min. Is that the min thickness in the curved piece for any type of flare bevel weld? Or can a smaller weld be used?

 

[JLNJ]

Since these welds are PJP and the effective throat is significantly smaller than the weld size, I don’t think you want a nominal weld size smaller than 3/16.

 

[WARose]

Thanks. The thing about it is: does that 3/16" mean the possibility of a burn through? If so, I don't have any choice but a smaller weld.

Here is the situation: I am trying to weld a Unistrut P1000 channel (12 ga) to a 1/4" plate. I am calling out a 1/8" flare bevel groove weld. But I was put off by what I noted in the OP. So I am not sure here.

 

[jittles]

Is there any guidance in AISI? Your weld may be governed by the light gage welding provisions with the 12 ga side of things.

 

[WARose]

Is there any guidance in AISI? Your weld may be governed by the light gage welding provisions with the 12 ga side of things.

That was something I was hoping someone here would know. But the metals I am using (all carbon steel with the SMAW process) should make this a generic question. The bottom line question is: is that 3/16" (min) based on a burn through concern or something else?

 

[WinelandV]

Hmm... despite having called out numerous flare-bevel welds on 1/8" and 3/16" square HSS (ASTM A500, so the thickness could be 0.93*t_nom), I've never noticed that required thickness on the curved part. For the 1/8" tubes, I always cautioned the welders to take it easy, so as not to put a hole in the side. But now I'm curious - perhaps none of those welds conformed to AWS specifications.

Maybe you should re-post in the Welding, Bonding & Fastener engineering forum.

Please note that is a "v" (as in Violin) not a "y".

 

[GC_Hopi]

I think JLNJ is correct. AISC has 1/8" min effective throat (Table J2.3, AISC 360-16) and if you look at the fit up tolerances they are -1/16" so 3/16" - 1/16" gets you to 1/8".

 

[WARose]

For the 1/8" tubes, I always cautioned the welders to take it easy, so as not to put a hole in the side.

The thing about it is: I've seen people call out (when light gauge welding) a weld size equal to the thickness of what is being welded. (You can see it in Yu's text on the subject as well.) Just never been too sure if that is ok. In AISC welding, we always were taught the max. fillet size (for example) is the thickness of the material - 1/16". But that won't work for light gauge.

 

[GC_Hopi]

Take a look at this article, Link. As jittles said this welding would fall under a AISI code and not AISC.

 

[WARose]

I've dug into AISI's code and Yu's text on this topic. I've come to the conclusion that you can have a flare bevel groove weld with a leg/effective throat well in excess of the material thickness without a problem. Like a lot of codes, it doesn't explicitly say it....but it's implied. For example, in Sect. J2.6 of AISI S100-16, they give capacities for (and illustrate) such thicknesses that are obviously much larger than the wall thickness of the connecting part.

And hopefully a good inspection follows all this.

 

[dauwerda]

In AISC welding, we always were taught the max. fillet size (for example) is the thickness of the material - 1/16".

This is only true/required when welding on the edge of the material (and that material is greater than 1/4" thick). It is not true for something like a Tee Joint.

I do believe the min thickness requirement is due to a concern with burn through. Keep in mind that AWS D1.1 specifically states it is only for steel of thicknesses of 1/8" and thicker, so technically you would be more in the realm of D1.3 with the Unistrut.

 

[JLNJ]

The effective throat is related to the radius of the flare. So you are looking at an effective throat of 5/16 * radius or 5/16 * 2*wallthickness or 5/16 * 2 * .125" = .078125. Just 5/64ths of an inch.

It's a little unclear to me in the AWS spec, but I think you need to fill that weld flush to develop this capacity.

 

[WARose]

I am not familiar with D1.3.....but it would seem to me that it all kind of melting together (sort of like a puddle weld) is about the only the way welds of materials this thin would work.

 

[WARose]

The effective throat is related to the radius of the flare. So you are looking at an effective throat of 5/16 * radius or 5/16 * 2*wallthickness or 5/16 * 2 * .125" = .078125. Just 5/64ths of an inch.

It's a little unclear to me in the AWS spec, but I think you need to fill that weld flush to develop this capacity.

Yeah, that's from Table J2.6-1 is AISI. And I agree that section is a little confusing. I think if you fill it flush you are in one section of J2.6.....but you overfill it....you get kicked into other sections.

 

[gtaw]

If the governing document for welding is an AWS standard, the term "Throat" is reserved for fillet welds. When a groove weld is being discussed, the proper terminology is joint penetration or weld size. Weld size is the sum of the joint penetrations if the joint is a double groove weld, otherwise, the weld size is equal to the joint penetration for a single groove weld.

With regards to the flare bevel and flare V-grooves, AWS D1.1 provides the size of a prequalified flare bevel and flare V-groove in a table Table 4.1 in D1.1:2020). The specific table depends on whether one is using D1.1:2015 or D1.1:2020. In either case, the size is a function of the radius of the rounded surface, the welding process, and the position of the groove when it's welded. The size is the maximum prequalified weld with the presumption the groove is filled flush.

No credit is given if the groove is filled beyond flush, i.e., reinforced. A reinforcing fillet weld in the case of a flare bevel groove is a different matter.

With regards to lap joints, when the thickness of the lapped member is 1/4-inchor more, the maximum weld size is 1/16-inch less than the thickness of the lapped member.

I hope this is useful.

Al

Best regards - Al