Tried a flux core welder for a boiler patch in January, what a mistake

I needed to weld a patch on a 3/8th inch boiler plate up on a roof in St. Louis and my MIG was acting up, so I grabbed my buddy's flux core setup. The slag was a nightmare to chip off in the cold and I ended up redoing the whole seam after it failed a pressure test. Any of you guys use flux core for boiler work or do you stick with stick? It just seems like more trouble than it's worth.

2 comments

2 Comments

the_jason14d ago

Man that brings back a memory from a few years back, I was fixing a dock gate down at the river and it was freezing rain, trying to run some 6010 root passes. I was layered up like the Michelin Man and couldn't feel my fingers, the rod kept sticking and the arc was just hunting all over the place. Ended up having to come back the next day when it was warmer and got it done in like an hour. Funny how weather just ruins your plans when you're trying to get something done that needs to hold. Your buddy's flux core machine might have been fine for some car body panels or light fence work, but that boiler patch needed real heat and controlled cooling. Cold metal and wire feed just don't mix well, you get all that porosity and slag inclusion that'll fail a pressure test every time. Live and learn I guess, at least you caught it before it blew.

sam_harris6814d ago

Hold up on that flux core for pressure vessel work, that's not the right tool at all. Flux core is designed for structural and general fab work on thinner metals, not for boiler patches that need to hold pressure. Stick welding with 7018 rod is what you want for something like that, especially when you're dealing with 3/8ths plate that's going to see high pressure and heat cycles. The slag issue you had is real, flux core just doesn't give you the control you need for deep penetration on thicker material in cold conditions. Even your buddy's machine probably wasn't putting out enough amps for a proper weld on that thickness. Boiler code work really calls for stick, and you're asking for trouble if you try to cheat it with a wire welder.