Weld size of butt welds 4

[BillCat66]

Is there a limit on size of weld for butt welded joints at 90 degrees. Specifically I want to join a 1" plate at 90 degrees to a 1/4" plate with a fillet weld on one side. Is 1/4" weld acceptable?

 

[metengr]

The weld joint configuration is a T-joint. The minimum size of the fillet weld is based on either the lesser thickness of the two members being joined or determining the size of the fillet weld based on applied loads. In this case, a 1/4" leg length is the minimum. I would still check to assure the load-carrying capacity of the weld is also acceptable.

 

[flamby]

1/4" size is actually the maximum you can be allowed to do without deforming the plates. Lesser welds are allowed based on your calculations and strength requirements.

Ciao.

 

[metengr]

flamby;
Smaller size welds are not very effective, and I would not recommend it. If you look at most Codes and Standards and the book Design of Weldments by Blodgett, 3/16” - 1/4" fillets are about it for 1/4" plate thickness. Anything smaller is a tack weld, and I wouldn't depend on this for load-carrying capability.

 

[tab1999]

I agree with Metgengr,
There are specific requirements for non-low hydrogen that is outside the note below.

D1.1 Table 2.2
1/8" single pass Fillet Welds are acceptable for metals where the thickness is less than or equal to 1/4"
(note: the minimum size for dynamically loaded structures is 3/16in. - 5mm.) If these are sufficient to satisfy design requirements.
There are lots of variables like pre-qualified joints etc.

 

[deanc]

http://www.eng-tips.com/viewthread.cfm?qid=148680

Check the links in this post.

 

[LowLax]

AISC Spec:
Minimum: 1/8"
Maximum: 3/16"

 

[JoeTank]

LowLax
Can you cite the reference that states max fillet weld size is 3/16"? The reason I ask is that the codes and standards I am familar with have no problem with a full fillet weld size of 1/4" for this type of tee joint.

Steve Braune
Tank Industry Consultants

http://www.tankindustry.com

 

[RARWOOD]

I would agree with metengr, that the minimum fillet weld size would 1/4" unless a larger size is required for strength.

From my old "Steel Structures Design & Behavior" Salmon & Johnson, "fillet weld sizes are governed by the thicker of the two pieces being joined, except the weld size need not exceed the thickness of the thinner piece joined unless a larger size is required by calculated stress.

It is my understanding that the thicker plate draws heat away from the joint so a larger fillet is required to avoid incomplete fussion.

If the use of an 1/8 fillet to join a 1/4" plate to a 1" plate is now allowed, I have a lot of applicatons where I could save on welding costs.

 

[HgTX]

The 3/16" maximum would only apply for a lap joint.

Hg

Eng-Tips policies: faq731-376

 

[tab1999]

RARSWC,
1 item to consider when joining 2 extremely different thicknesses of metals is preheat to minimize stress cracking etc. due to the larger metal robbing the heat input.

 

[RARWOOD]

tab1999

I have a small understanding of welding procedures, but I don't get involved in specifying welding procedures.

In my work I just specify the type of weld. 98% of the welds I specify are fillet welds 3/8" and less. All my company's welding is done by other vendors.

In most case I work with even the minimum weld size allowed provideds more then the enough strength. I design mostly steel used in wood connectons, so the weak element is normally the wood.

With all the responses to the intial question I am still confused. Some of the responses seem to indicate that I could welded a 1/2 plate perpendicular to a 1" plate with a 1/8" if the 1/8" fillet had sufficient strength.

 

[VeryPicky]

What code are we talking about? ASME VIII or structural?

Putting Human Factor Back in Engineering

 

[RARWOOD]

VeryPicky

I am not familiar with the ASME VIII code so I rely on the AISC Manual.

In the applications I deal with the weld size is more dependent on the minimum size required than on strength. The weld configurations I deal with are also governed by company policy.

For example if I was welding up a base shoe that had a 12" x 12", 3/4" thick base plate with two 12" x 8", 3/" thick vertical side plates space 9" apart. I would call for a 3/8" fillet on the outside of the two vertical plates, which based on my understanding would be the minimum fillet allowed by the AISC code. Then following company policy I would use a 3/8" fillet on the inside. A "T" joint with two 3/8" fillets.

In a typical application the uplift on the vertical plates would be around 11 kips per plate.

There are a lot of times in the application above where I would like to call for a 1/8" fillet on the inside. Now I could just treat the inside weld as a tack weld and not depend on it for strength. However there are times when I would like to be able to assign a load value to it or even use 1/4" on the outside with 1/8" on the inside.

Now you might wonder why I need a 3/4" thick base plate. The problem I run into is that sometimes the EOR will specify minimum plate thickness. So where I could use a 3/8" plate, I may be required by the EOR to use 3/4" plate.

 

[tab1999]

RARSWC,
You mention that you depend or rely on AISC for design.
I'm fairly sure that AISC refers to AWS D1.1 for materials starting at 1/8" minimum.
AWS is where I got the information above about usiing 1/8" single pass Fillet Welds being acceptable for metals where the thickness is less than or equal to 1/4"
You should try to get the latest edition of AWS D1.1 for reference.

 

[RARWOOD]

tab1999

I will try to borrow the latest edition of AWS D1.1 from one of our consultants.