I'm back.
Finally had to rebuild the forge. The last couple of burns, the floor of the forge was turning molten.
On the last burn part of the refractory came down off the ceiling of the forge and the firebrick under it started to turn molten and even had a few drips! Those two Atlas 30k burners are putting out the heat. Below is a write up with pics of the forge being disassembled.
Forge as originally built. Yeah, I know the hard fireplace bricks aren't meant for forge builds but it is what I had/could afford at the time. It lasted longer than I thought.
Took the forge apart this past weekend and rebuilt it using the new insulating (soft) firebricks. First few pictures show the extent of damage/degradation and why hard fireplace firebricks from the big box store are not fit for a forge. But they got me started and held up longer than expected.
Top view, straight down, burners removed.
Top view, angle, burners removed.
Inside of top, straight view, removed from rest of forge.
Inside of top, angle view, removed from rest of forge.
Inside of forge showing floor, straight down.
Inside of forge showing floor, angle view.
Floor of forge removed. To show how extent of how the firebrick melted.
That piece hanging was sitting outside the opening of the front of the forge. Basically a shelf to set a piece on so it didn't stick to or pick up any of the molten floor. It just barely touched the molten floor inside the opening and when the forge cooled after last use, it stuck.
Some shots of the reassembled forge with the new firebricks.
Did a brief test fire. Basically wanted to fire it up to try out the new build. I didn't heat anything up to forging temps; just needed to heat up a few S-hooks that I was making for a friend to black hot so I could dip them in mineral oil and then wipe them down. This gives them a decent finish. During even this brief test fire, the sides and the top look like they will be a big improvement. The floor is another story. As shown in the pics below, the fire impacts these directly. Towards the end the spot (little bigger than a quarter) looked like it was starting to bubble up. Not good. I'm not sure if the bricks should be able to take the direct impact of the flame or if I need to add a layer of refractory cement. Need to do some more research. In the meantime, I'm going to replace the two bottom bricks with hard firebrick to see if that will hold up better.
Ended up replacing the floor bricks with hard firebrick I'd picked up a while back. Not the thin fireplace bricks used in the original build. Still not sure if I need to line the interior surfaces with refractory cement or not. Input would be much appreciated.
Looking up into the forge. You can just barely see the end of the burner in the holes.
First startup after installing hard bricks for the floor.
Been burning for about 10 minutes or so. Floor starting to glow but remains solid.