Minimum Weld 1

[chideb]

When you weld a 1 1/4" dia rod to a 3/4" bar via a slot in the end of bar, looking at the placement, you have a natural flare bevel because of the geometry which you weld first all around allowing full penetration(since the rod diameter is larger than the plate thickness and there is a 1/16" gap between the rod and bar) and you finish your weld with a fillet, do you have to still use the minimum 5/16" fillet weld in a single pass per AISC for material greater than 3/4" or could you use 1/4" and considered the strength of the flare bevel weld?

 

[racookpe1978]

Stop. Take a breath, add a period or two or three, and draw a sketch. 8<)

Post it to clarify your configuration. It will also help answer your question.

 

[Lion06]

I would say you need a minimum of 1/4" weld, because your THINNER part is 3/4" or less. AISC bases the minimum fillet weld on the thinner part joined. This is new in AISC 360-05. That being said, I wouldn't count on the fillet for strength. You'll have a max overhang of 1/4" on each side of the bar, but that quickly tapers off to nothing, so your fillet weld goes from 1/4" (maybe 3/16") to nothing very quickly. Can you use a 1 1/4" bar to get a "truer" flare bevel?

 

[racookpe1978]

Also, what are you using as your definition of the fillet size: US convention is base length, DIN defines fillets as throat thickness, .707 the base length.

And, why is the small change in fillet size critical? What do you gain - and be specific please - by accepting a weaker, 80% smaller fillet weld on this part?

 

[chideb]

I've attached a sketch.

 

[Lion06]

racookpe-
Was that question directed to me?

chideb-
I don't know if I believe that what you have will cut it as a prequalified weld. I think you're going to have to come up with a different configuration or else have a procedure qualified for this type of weld. The way it stands now, very little weld metal will get into that "flare bevel" area. What grade steel is the rod?

 

[DABwilldo]

A couple thoughts.

I've seen joints such as you describe in the field. I don't know if your end use application is the same as what I've seen....

I would not count on getting a full penetration weld with the joint configuration you sketched out. Even with the radius of the rod allowing some access below the surface of the bar, that's a lot of material to burn through to get to the center of the joint; even with SMAW or FCAW processes.

If you were to hand those pieces to me and request that I joint them with a full penetration weld, I'd bevel the corners of the bar slot on both sides, such that the root face was no more than ~3/16" thick. I'd also enlarge the root opening to ~1/8" all the way around. This would ensure full penetration on the first pass. It would also allow the welder to grind the opposite side of the first pass in order to remove any slag that deposited out on the root side of the first weld pass.

see the attached .jpg file for illustration of bevel prep on bar side of joint.

I'd also bevel the end of the rod, with a double bevel, ~1/8" root face, ~1/8" root opening, about a 30° bevel angle for SMAW welding; smaller for FCAW, or even larger for GTAW. That would make it easier to ensure full penetration into the bottom of the slot in the bar, where the end of the rod meets the bottom of the bar slot. This would be simpler than grinding the bevel on the bottom of the bar slot, I think.

 

[chideb]

DABwilldo
The end use is a tension rod for a tower. The member load is 26K abd the steel grade is 50. Is it necessary to weld to this extent? Thanks

 

[racookpe1978]

Look at your own work: "The member load is 26K abd the steel grade is 50. Is it necessary to weld to this extent?"

What is the formula "you" are going to use to calculate the linear inches of weld required? In other words, what were you going to use for "K" in your equation of:

Linear inch = K x Force/Tfillet where Tfillet is the fillet weld thickness

 

[racookpe1978]

StructuralEIT (Structural) 13 Aug 09 8:37
racookpe-
Was that question directed to me?

---

No, my question was directed back to the original poster.