Welding symbol 4

[precast78]

I thought I understood it completely but now I have a disagreement with a coworker and we are not sure who is right. Let's say you put a welding symbol on a drawing, do you put the leg size or the effective throat size? It seems more sense if you put the leg size. This website for example shows the leg size (page 3)

http://www.metalwebnews.com/howto/weld-symbols/weld-symbols.pdf.

Now if you look at AISC steel manual under Table 8.2, It is tell us to put the Effective Throat size. Which is correct?

 

[SteelPE]

Are you referencing PJP welds? I try to follow the procedure found in AWS for the type of weld that I am looking at which usually the size of the bevel and the effective size of the weld. I was once told during a seminar that if you are not quite sure call out was you are looking for in the tag of the weld.

 

[JAE]

I believe that with AWS standards most fillet welds are leg sized. I've never seen a fillet weld indicated with an effective size shown (as 0.707 x the leg size).

For complete joint penetration (or partial joint penetration) groove welds you would indicate an effective throat size using parentheses around the size.

In some cases (as in your attachment) you can show both.

 

[dhengr]

Precast78:
If we are still talking about your previous thread, you call out the leg size of a fillet on the drawing (w/ the weld symbol), but you design using the throat. That has been the std. for a long time. The min. throat area plane is the plane about which that fillet weld will fail. What is the min. radius from the root of the weld cross section? That’s the min throat. I don’t know what Table 8.2 shows exactly, but look at all the footnotes, and surrounding commentary and if they are talking about the throat dimension it is because that is the area (throat size/dimension)(unit length) = Area per unit length, to which you apply the allowable weld shear strength, to get the weld cap’y. Fillet welds usually show a cross section as a 45̊ triangle, but in some situations you can have/use an unequal leg fillet.

 

[gtaw]

What we have here is a failure to communicate.

The term throat is reserved for use with fillet welds and skewed T-joints. It generally refers to the shortest failure path through the fillet weld.

The skewed T-joint is a different animal. The weld is neither a fillet weld or a partial joint penetration groove weld. It is simply a welded skewed T-joint.

By definition (with the exception of AWS D17.1) the fillet weld is required to have fusion to the root. The structural welding codes stipulate the angle between the adjoining surfaces (dihedral angle) must be equal or larger than 80 degrees, but less or equal to 100 degrees. The Engineer and the contractor specifies the fillet weld by the leg dimension. If the dihedral angle is between 60 degrees and 80 degrees or 100 degrees and 135 degrees, Annex B applies when the work is per AWS D1.1. If the dihedral angle is between 45 degrees and 60 degrees the Engineer specifies the minimum throat required to transmit the applied load. The fabricator is tasked with converting the throat dimension (as shown on the S-drawings) into a leg dimension including any allowance required for the Z-loss per the applicable table (2.2 or 2.9 found in AWS D1.1-2010).

In the case of partial joint penetration groove weld, the dimension through the weld is called the joint penetration or weld size. It hasn't been officially called the "throat" for the better part of 30 years. Time passes and terminology changes.

Best regards - Al

 

[jvvse]

AISC is very clear on what the number next to a weld symbol means. Usually the number is the "leg" length, and if you want to specify the throat thickness you put it in paranthesis.

3/4 means a 3/4" leg
(3/4) means a 3/4" throat

 

[racookpe1978]

US standards and US installation and US drawing and US welder and US inspector?
Dimension the leg size. ALWAYS. Be clear what you dimensioning, or reference it clearly.

Euro dimensioning scheme and Euro welder and Euro inspector?
Dimension the throat. Be clear you are dimensioning the throat, or reference that standard.


The Euro form is "less safe" that the US standard because
(1) you cannot measure the throat directly.
(2) If somebody screws up and welds the throat to the thickness you assumed was going to be the leg, the weld will be thicker than expected. Not thinner by 0.707
(3) I can (I have!) put a weld gage on both legs of a fillet and measured them many, many times. Shown the welder where he was "short, and where he was "long" (too big) and was wasting time. That's much harder with a throat dimension: You still have to measure the legs and assume the throat size.

 

[DerbyLoco]

EN 22553 which is the European standard for the representation of welding symbols allows either throat or leg length to be specified. For throat depth you put an 'a' before the required dimension and for the leg length it is a 'z'. We always used to use the leg length in our Derby workshops but we now use the throat dimension as that is more favoured by our other sites and also by the Stress Analysts

 

[gtaw]

Let's be clear, in the world of AWS the term "throat" is reserved for fillet welds. It hasn't been a proper term for groove welds for nearly 30-years.

Older texts (and older professionals who haven't kept up with the latest revisions of AWS standards) may use the term throat incorrectly when specifying the weld size (joint penetration) of both partial joint penetration and complete joint penetration groove weld.

AISC refers the reader to AWS A2.4 for the proper use of welding symbols. Likewise, AWS A3.0 is referenced by AISC for welding terms and definitions. Like all ANSI standards, AWS standards are subject to a 5-cycle of review, revision, or reaffirmation. The system provides the AWS with a positive cash flow and those that use the AWS standards with a negative cash flow. However, professionals are expected to use the relevant edition of the applicable standard. Standards that are out dated can lead to misunderstandings, misinterpretation, or worse.

Best regards - Al

 

[precast78]

I get it now. But on table 8-2 on AISC steel manual states to put throat size behind the symbol. It is not stated anywhere to put leg size for fillet. Thanks everyone!