Welding symbol questions (fillet welds)

[HgTX]

1. Double fillet symbols can be used for both T and lap situations (though AWS A2.4 doesn't seem to show the use of this symbol for a lap joint--is that an omission, or are other references showing this usage incorrect?). They also get used, for example, to show that both sides of a long narrow member get welded to something (like the long sides of an angle connecting to a gusset, as in A2.4 Figs. 8(C)&(D)). I see that as sort of a big-webbed T joint. Question: how large can a member be before two welds on it can no longer be considered "both sides of a joint"? How long can the lap be? How big can the member be that has two sides welded? Can a double symbol be used for welding top and bottom edges of a large channel onto another plate?

2. If I want to weld continuously around three sides (say around the end of that angle again), I use one symbol with three arrows. What if I wanted three separate welds? Would I do that with separate symbols? Or is the triple arrow silent as to whether the three sides are continuous or separate? AWS A2.4 section 3.6 says multiple arrows for identical welds (which could mean unconnected welds, say at the top and bottom of a large plate), but then 3.9.2 and Fig. 9(A) say that multiple arrows are used for changes in direction within a single weld.

Here's how I see it:
On adjoining edges, multiple symbols mean separate welds and one symbol with multiple arrows means one continuous weld. On nonadjoining edges, multiple symbols or single symbol with multiple arrows mean the same thing.

But is there code backup for that interpretation?

Hg

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[metengr]

HgTx;
Some background information regarding welding symbols that might help.

http://www.tpub.com/steelworker1/29.htm

http://www.khake.com/page89.html

Look for welding symbols

 

[unclesyd]

You might want to get this book for your library. Look at section 6.2-9

Design of Weldments
Omer W. Blodgett

https://ssl.lincolnelectric.com/lincoln/spmount/store.asp?cat=7

 

[henri2]

It took me a long time to get comfortable with welding/weld symbols. An AWS seminar really helped me.

My responses below are based on the 98 edition of A2.4.

1. A double fillet weld symbol is shown in Fig 8(B) for the combined intermittent and continuous weld both sides of the T-Joint. Go to Sections 5.1.2 (refers you to some figs) and also look at figure just below Section 5.1.3 for further explanation. The fillet weld symbols in Figures 8 (C) and (D) shows two arrow-sided fillet welds in each case and not double fillet welds.

Regarding the channel if it is oriented as shown in AISC-ASD 9th edition page 1-40, where top right hand and bottom right are the edges you refer to, and you want to weld the top side of the top edge and the bottom side of the bottom edge, I would use two separate single arrow-side fillet weld symbols. If it’s the top left hand and bottom left hand, then a double fillet weld will work since they are in a common plane (your big webbed T analogy comes into play) or you could use two separate fillet weld symbols

There are numerous combinations of joints and weld symbols possible; perhaps too many to include for the intended scope of A2.4. This may explain why AWS A2.4 does not show one for a lap joined with a double fillet.

2. Figure 9 (A) would work if the fillet weld size was the same. If you wanted three separate fillet welds because you did not want it continuous as shown in figure 9 (A) and or because the weld sizes were different along each side/edge then three separate weld symbols would be the way to go.

I agree with the last point you made regarding non-adjoining edges

 

[HgTX]

unclsyd--doesn't look like they're actually selling Design of Weldments. Is there anything similar in Design of Welded Structures?

henri2--In the channel figure you describe (channel vertical looking like a "C"), I'm looking at welding the top left and bottom left--meaning the channel is flat against a gusset and I'm welding it top and bottom (okay, I personally am not welding anything). So you're saying that any two fillet welds to parallel edges of the same member in the same plane of the same size can be indicated with a double fillet weld symbol? Do they have to be welded *to* the same member, or could the double symbol then be used to weld opposite *ends* of the channel to different gussets? (I'm thinkin' no, but then I don't like using the double fillet weld symbol for large members. A small angle is one thing, but a W27??)

Okay, one more confirmation--if separate symbols are used for three sides around the end of a member, then they're definitely *not* one continuous weld, right?

Hg

Eng-Tips guidelines: faq731-376

 

[unclesyd]

HgTX,
Strange things happen in the ether. I just went to the site with the link I provided and the results were the same as you saw, no sale. Clicked on the contact button, sent an message asking them the status of the book, clicked on the books button and behold there is the book for sale.
You might try that approach, go to the foundation home and then to books I think it is worth the extra click or two.
As for the Design of Structures it has been so long since I used the book I can't recall. I had both but seldom used the Design of Structures as everything I needed referenced was in Design of Weldments.

PS:
Inflation is bad, I paid $3.00 for my first one. I had to buy several as they have legs.

 

[BillPSU]

Welding symbols on a drawing show the required size, shape, and locations of welds however there are usually some quality procedure at a manufacturer which give additional instructions about welds. The manufacturer where I worked required all corners to be wrapped and no start/stop points left in those areas to reduce stress concentration points. Use of additional weld symbols for clarity is very appropriate however some drafters and their supervisors have decided extra weld symbols are an extravagance their drawings can do without and assume shop people will intrepret the drawings the same as they do. Just like right now, I am referring to low carbon steel weldments using up to 60k yield material.

Intrepretation and application of weld symbols is based on the overall process used to manufacture a product.

 

[henri2]

HgTX,

It is preferable for the welding symbols to convey information unambiguously with as much clarity as possible. In my opinion, for the channel, two separate single arrow-side weld symbols are much easier to comprehend than the double fillet weld symbol. In the case of the angle the intent of the double fillet is obvious.

Use of welding symbols that will make the fabricator or quality control inspector utilize critical thinking skills is good for a CWI or SCWI exam but not for fabrication purposes.

 

[HgTX]

Try telling that to the guy who created these plans I've been struggling with...he won't listen to me.

Hg

Eng-Tips guidelines: faq731-376

 

[BillPSU]

The person who created the drawing doesn't know who his customer is. The customer is the welder, the QA/QC person, the Mfg. Eng., and the toolmaker. The part may finally get delivered to the end user but the end user doesn't use the drawing and could care less about the drawing. The people in the shop DO care.

 

[henri2]

HgTX,

Is the guy who created the plans famliar with A2.4? Are these shop drawings?

 

[HgTX]

These are plans. Standards, actually. He claims A2.4 backs him up, and now we head out of welding territory into human issues. I started this thread to get a sanity check before I drive 20 miles over to his office to draw some pictures. Fortunately someone else at his location agrees the symbols are misused and maybe I'll be spared a drive and another argument.

Anyone gots a rule of thumb for how big a member can be before using a double symbol for welding parallel edges gets silly, if still legal? I'm okay with angles, bars, and small channels (maybe a single-digit number of inches deep). I think I'm okay with WT sections. I'm not okay with big honkin' channels, W sections, or a piece of plate that I don't think looks like a bar. Anyone else have a sense for this?

Hg

Eng-Tips guidelines: faq731-376

 

[henri2]

HgTX,

A compromise might be reached if they still insist on the double fillet weld. Consider adding a note, perhaps in the tail of the welding symbol, which directs them to a detail which has isometric representations of what the finished weldment should look like.

One last question. Will the fillet weld be continuous along both edges, staggered intermittent or chain intermittent?

 

[HgTX]

Continuous. Not very long, though. What they're actually going for is a C-shaped weld around 3 ends of a diaphragm member onto a gusset, plus one weld on the back side, and then something similar connecting the gusset to another member. The only way I can make any sense of double-sided symbols in that context is that one handles the end weld (the vertical of the C) and the backside weld together as a lap joint, and then one handles the top and bottom of the C on opposite sides of the diaphragm shape. But that would mean three separated welds on the front side, not one weld running around 3 sides. Which is actually in violation of code for this application--end welds must be carried around to the sides.

What they need is one single-sided symbol for the back weld and a single-sided symbol with three arrows for the three sides in front. I don't think he'd disagree that that is at least an option, but he doesn't see how what he has is NOT an option.

I'll wait & see if my other colleague wins the argument before I make the drive over...

Hg

Eng-Tips guidelines: faq731-376

 

[henri2]

From what you have described, your option seems to be the way out.

 

[deanc]

CYA!!!!

Keep notes and logs of all your discussions. People,time date.

Make sure the prints are signed and dated.

If thats the way they want it and are willing to pay--build it.

You may get a second job for the rework.

 

[HgTX]

We're supposed to be on the same side...actually, we usually are. I'm surprised at this situation. Neverzeless, I have faith that truth and justice shall prevail.

I think I'll suggest to the A2.4 people that they add an example of double weld symbol for lap joints, though. I'm not the only one who's been unsure of this.

Hg

Eng-Tips guidelines: faq731-376

 

[HgTX]

The A2.4 people point out that the lap joint is shown in paragraph 3.1.

I must have looked right at that and missed it.

Hg

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