Welding Tips and Tricks

I am very curious, what rods are supposed to be used for structural steel when its painted with epoxy paint? I would guess 6010 rod for the root and 7018 as a cap if the weld needs to be certain size... like 1/4" for example.

Are you supposed to clean off every tiny spot where theres paint to weld with 7018 only?

Because to me, that doesnt make any sense.

I basically did 3 hours of welding with 6010 vertical and horizontal on some steel beams and it even looked good for 6010 welds, and when the foreman came around to inspect, he thought they wouldnt pass the way they were. He sent the pictures to a CWI and indeed he said that the 6010 welds looked scary and they wouldnt pass alone for structural code.

So I said okay Ill cap these two joints with 7018. I capped them, they took pictures and the CWI then said, the plate shims we had to take up the space, were not a proper weld joint configuration.

So yeah, i didnt get to see any blueprints.... the construction company just showed me what they wanted and let me run today... but by about 2:30 it turned into a shit show.

blakef wrote:I am very curious, what rods are supposed to be used for structural steel when its painted with epoxy paint? I would guess 6010 rod for the root and 7018 as a cap if the weld needs to be certain size... like 1/4" for example.

Are you supposed to clean off every tiny spot where theres paint to weld with 7018 only?

Because to me, that doesnt make any sense.

I basically did 3 hours of welding with 6010 vertical and horizontal on some steel beams and it even looked good for 6010 welds, and when the foreman came around to inspect, he thought they wouldnt pass the way they were. He sent the pictures to a CWI and indeed he said that the 6010 welds looked scary and they wouldnt pass alone for structural code.

So I said okay Ill cap these two joints with 7018. I capped them, they took pictures and the CWI then said, the plate shims we had to take up the space, were not a proper weld joint configuration.

So yeah, i didnt get to see any blueprints.... the construction company just showed me what they wanted and let me run today... but by about 2:30 it turned into a shit show.

In my little experience with structural it required no paint within 3inches of the weld zone, and it was 7018 only.

Uh oh.... why a medium/low penetration rod for root burns and fillers?

Also, that means all the surfaces have to be perfectly clean..... how do you get into a corner with a 4.5" grinding wheel or grinder in general?

Sand blaster or chemical stripper.

7018 was speced out due to its ductility.

Poland308 wrote:Sand blaster or chemical stripper.

7018 was speced out due to its ductility.

So in the future, I would be quoting for not just the welding, but also prepping the joints and preferably have another guy ahead of me that does this?

Trying to figure out real-world scenario here.

So searching around some more today and I found this:
"Known by various names - shop primer, weld primer, pre-fabrication primer - a primer will protect the steel during fabrication, which may take several months. It then serves as a first coat for a subsequent paint system. All primers are designed to be quick drying so that they can be applied by mechanised spray guns as the plates are moved through a paint spraying cabinet.

However, using primers may have adverse effects on welding behaviour of structural steel. Primer may be removed locally before welding, but this operation is expensive. Thus, there are many advantages in directly welding primed plate. The principal problem when welding primed plate is porosity. The organic binder used in primers can break down to form hydrogen, water and carbon dioxide, and hydrogen or water vapour can be trapped in solidifying weld metal, depending on the solidification rate of the weld."

Now this makes more sense. If a construction company sub-contracts a welding company to come out and weld, the joints must be RECENTLY cleaned, blasted, or stripped of any paint and material coating to be ready to accept a 7018 weld rod.

Otherwise if the joints are not prepped, it is up to the welding company and construction to determine who will be responsible for preparing the joints.

The welding company should be charging atleast double the normal rate if they are running a one man show per truck. This would factor in the cost of a helper/joint prepper to go ahead of the welder and prepare all the joints the same day of working.

If you have any anything to do with the painting, have the people mask off the are to be welded. It's not that hard. The thing to remember about weld through primers are that they are designed to work at a very specific thickness. **microns of thickness. If it's anything thicker than the stated design, you're going to have trouble.

When we have to do something like this we contract a pro/ industrial painter to do the prep, and to repaint it after.