Forge Burner Tube Getting HOT

[jnaught]

The weld for the collar of my first burner started to glow during yesterday's forging session and the whole top of the furnace started to bow up:

I switched to the middle burner and it cooled down pretty quickly, but clearly that is not how it should be. The fire bricks in the lid of the forge are cracked, but they've been cracked for a long time. Is this what is causing it?

Any suggestions on how to fix it? Its a 15+ year-old 3-burner from Majestic Forge. I'm leaning toward just replacing the bricks, but if there is an easier fix (or if something else is the problem), I'm all ears. Thanks!

 

[DevinT]

The brick is supposed to be an extension of the burner. You are getting some pre-burn between the brick and the shell.

Hoss

 

[Stacy E. Apelt - Bladesmith]

Hoss has it. Replace/repair the bricks. While doing that, examine the end of the burner tube to assure it isn't eaten back too far.

 

[jnaught]

The brick is supposed to be an extension of the burner. You are getting some pre-burn between the brick and the shell.

Hoss

Thanks! That is what I suspected.

Hoss has it. Replace/repair the bricks. While doing that, examine the end of the burner tube to assure it isn't eaten back too far.

Roger that! I hope it won't be too bad as this is the first time I've noticed it getting hot like that, but I'll pay attention.

I've also reached out to the manufacturers to ask about what type of bricks they recommend; there is a lot of variety. Any input you all have on that would be great. Thanks!

 

[Stacy E. Apelt - Bladesmith]

K-26 bricks should work, but I personally would use kao-wool and coat it with something like Kast-o-lite 30 or satanite.

 

[jnaught]

Thanks! I'll look into those options too.

 

[jnaught]

I’ve begun the repair!
Lynn Manufacturing 2” thick ceramic wool cut to fit the lid:


Satanite spread in lid, mostly concerned about sealing around burner outlets:


Wool pressed in place:


And everything covered in a first coat:


I worked it into the holes around the ends of the burner tubes, being careful to keep them open. I’m going to do at least one more coat on the whole furnace and two more on the wool/burner outlets and see from there. I’m letting it dry at least 24 hours before the next coat. Should I try to fire it lightly before the next layer?

 

[Stacy E. Apelt - Bladesmith]

I used to let it dry overnight and give it a light firing between layers. Then I got a powerful heat gun that does the job in about 20 minutes and allows control over corners and such. Once all layers and coatings are on, I dry it one last time with the heat gun, give it a couple days to dry up more, then start the firing cycles.