Maximum Economic Size of Fillet Welds Using SMA Process
Maximum Economic Size of Fillet Welds Using SMA Process
(OP)
What are the economics of using different size fillet welds in steel using shielded metal arc (stick) welding? I am designing the wales (steel beams placed against the excavation wall to support the wall) for an excavation, and the specifications require us to develop the full moment and shear capacity of the beam at splices. The contractor doesn't want to use groove welds because the welds would have to be x-rayed.
I'm guessing that it is usually cheaper to use longer lengths of smaller fillet welds than to use shorter lengths of larger fillet welds. For example, a 3/8" fillet weld might take weld passes, but a 3/4" fillet weld might require seven or eight passes. I don't know if it is even pracitical to use a 3/4" fillet weld, and in the past I have usually kept fillet weld sizes to under 3/8", but this application is going to require tons of welding. Thanks for your responses.
I'm guessing that it is usually cheaper to use longer lengths of smaller fillet welds than to use shorter lengths of larger fillet welds. For example, a 3/8" fillet weld might take weld passes, but a 3/4" fillet weld might require seven or eight passes. I don't know if it is even pracitical to use a 3/4" fillet weld, and in the past I have usually kept fillet weld sizes to under 3/8", but this application is going to require tons of welding. Thanks for your responses.





RE: Maximum Economic Size of Fillet Welds Using SMA Process
Please re-read the above carefully. Explain what "specifications" means. Just because the contractor does not want to x-ray welds should not be a reason to deviate from the original design. I see some serious problems here.
RE: Maximum Economic Size of Fillet Welds Using SMA Process
Blodgett gives a rule of thumb that fillet welds are more economical than groove welds if the required weld throat is 3/4" or less. But if your design calls for complete joint penetration, you can't just substitute a pair of fillet welds without consulting with the designer.
Hg
Eng-Tips policies: FAQ731-376
RE: Maximum Economic Size of Fillet Welds Using SMA Process
Picture a small and large fillet. The failure mode is throgh the throat of the fillet weld. The metal that is in the fillet weld that does not contribute to the throat is just extra material. It is requried to form the fillet, but does not add to the alowable strength. So in a small continuous fillet, the metal surrounding the throat is much smaller than on a large intermittant fillet weld.
RE: Maximum Economic Size of Fillet Welds Using SMA Process
Do you have to keep the stress under some limit? Are there fatigue considerations?
RE: Maximum Economic Size of Fillet Welds Using SMA Process
RE: Maximum Economic Size of Fillet Welds Using SMA Process
RE: Maximum Economic Size of Fillet Welds Using SMA Process
I spoke to a welding engineer who gave me estimates of the number of passes required to make different size fillet welds. He said that a 1/4" fillet weld requires one to two passes, a 3/8" weld requires four to five passes, and a 1/2" weld requires about ten passes. He added that fillet welds bigger than 1/2" are uneconomical.
Since the specifications require welds to develop the full moment capacity of the beam, shifting the splice to a location with lower loads isn't an option. As I suspected, while using fillet welds to make the splices is practical from a design and safety standpoint, it will be hugely expensive.
RE: Maximum Economic Size of Fillet Welds Using SMA Process
Hg
Eng-Tips policies: FAQ731-376
RE: Maximum Economic Size of Fillet Welds Using SMA Process
Also ask about increasing the size of the electrodes if not restricted by the weld procedure.
RE: Maximum Economic Size of Fillet Welds Using SMA Process
RE: Maximum Economic Size of Fillet Welds Using SMA Process
I also agree with GRoberts about choice of process.
Hg
Eng-Tips policies: FAQ731-376