Welding questions

[dcceecy]

We are doing some repair work. The existing I shape beam has a web of 3/16" thick. We are going to weld a continuous L6x6x5/8" angle along the web (the driection of the angle will be parallel to the web)

we specified 1/8" fillet welds 4" long @ 12" OC for the connection of vertical leg of the angle to the web (top and bottom).
but the contractor says the welds keep burning through the web (they are doing a mock-up).

I checked the AISC manual. 1/8" fillet welds is the smallest you can choose. I am wondering if the contractor is doing right.

Any suggestions? thanks.

 

[dcceecy]

Sorry. I have another question. If the existing steel beam are painted with epoxy. Do they need to grind off the coating or they can just weld through the wleds? (it will affect the construction cost)

Thanks.

 

[connectegr]

They have an incorrect setting on their welding machine or incorrect electrode diameter if they are buring through 3/16 web with 1/8 fillet welds. What welding process are they using? The travel speed for 1/8 fillets is pretty fast, burning through should not be an issue.

I have seen welds performed over painted surfaces. But I would recommend removing the paint. Refer to AWS D1.1 5.15

http://www.FerrellEngineering.com

 

[Michel60]

Good morning dcceecy,

I agree, blowing thorough 3/16" should not be happening with a 1/8" fillet. Is the web rusted or pitted? One other thing to consider is that epoxy paint can be some really tough stuff. It might be acting as an insulator and affecting the arc? I'd suggest having them check that the machine settings are with in the electrode manufactures recommended range, grind a little paint and then try again.

regards,
Michel

 

[MiketheEngineer]

Welder is doing something wrong.... BUT - going through Epoxy may/may not create some hazardous fumes that need to be addressed. Call the mfg.

NEVER weld on galvanized material unless your take precautions.

 

[Ron]

agree with connectegr...assuming SMAW, settings are too high for the electrode. If using GMAW or FCAW, likely using wrong settings and technique, causing too much arc distance. The machine settings will depend on whether AC or DC current is used, the welding position, the type and size of electrode, and the finished weld size.

Leaving the paint in place will increase the tendency to have inclusions in the weld deposition. If the welds are inspected using nondestructive techniques, they are more likely to be rejectable if welding over paint.

Attached is a stick electrode welding guide...FYI...

 

[dhengr]

I would get rid of the paint at the weld locations for the several reasons mentioned by others. And, I’d make those 1/8" fillet welds continuos. The many starts and stops are as likely causing (at least contributing to) the burn through problems. By the time you lay the stitch welds out, and then follow that layout, you certainly won’t be saving any welding time, and darn little filler metal for all the hassle. Get er started and keep going. You may make the welds in several foot lengths if you are concerned about distortion. You might also want to unload or support the beam while doing this welding.

 

[Eldorado]

I also agree with connectegr regarding wrong settings. Regarding weld length, if you only need the 4" in 12" that you are specifying, I would not change to a continuous weld.