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Unread 07-01-2008, 04:05 AM   #35
MayDay
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Exclamation JB-Weld Does NOT Survive in the Firebox!

BACKGROUND
Upon reincarnation as The Copper Cooker, Humpty has only had 4 firings so far:
---1. Bakeout #1. Low and slow. Overnight. T < 500F.
---2. Cookout #1. Low and slow. 7h. T < 500F.
---3. Cookout #2. 4h total. T < 500F.
---4. Cookout #3. 4h total. T > 550F briefly, 500F 1h, 400F 2h, 300F 1h.

Recent repairs consisted of 1 coating of JB-weld on all visible cracks, but NO application of furnace cement. New cracks appeared on the dome after the first 2 firings, but no further damage to the dome were noticed after 4 firings.

Disassembly of Humpty showed ADDITIONAL DAMAGE to the firebox and base.

JB Weld does not hold up in the firebox. Coal temperatures are too high for the material to withstand (500F temperature rating only). On the firebox, most of the JB has flaked off and/or turned into white powder. As a result, the JB no longer bonds or seals.


Close-up of JB deterioration.


JB has flaked off and broken down completely INSIDE the firebox.


Firebox came apart in 2 pieces. Most of the JB-weld has turned to powder wherever it was applied, so all the other old cracks will need to be dealt with again. See JB powder residue where the firebox has completely broken off.


CONCLUSION: JB WELD CANNOT BE USED IN THE FIREBOX.
(To repair the firebox again, I will use High-Temperature Furnace Cement only.)

JB seemed to hold up OK inside the dome. For today's repairs, the new cracks were sealed with JB and a second coating was applied over the old JB-welds.


JB also seemed to hold up ok inside the base. However, there were new cracks at the bottom of the pot (propagation from old ones). For today's repairs, the new cracks at the base were JB'd on the inside only, but not on the other side where the JB had flaked off. The old JB-welds near the inside top rim also got a second coat of JB.



TOMORROW'S PLANS
  1. After curing overnight, all JB-welds will be covered with High-Temperature Furance Cement.
  2. The firebox will be repaired with furnace cement only (no JB).
To be continued....
_____________________________________
Project Humpty: SLIDESHOW, PHOTO ALBUM

Last edited by MayDay; 07-01-2008 at 04:23 AM..
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