Two cracks are enough!! :coolmad: Worry no-more ;-) I`m not superstitious by nature, however, yesterdays Doctor visit with x-ray,,revealed a break in the support rod holding my Fibia together which was installed back in Dec. Even the highest Tech metals are inherent to stress. As explained, the healing process incures movement of the bone, applying stress on the plate, and in conjunction with walking and theraphy the plate failed at its weakest point (a screw hole). Thursday morning I get a new one :cheese: However I dont think its covered by a Warranty
Glad I have not upgraded stoves this year,,as my wood supply will be well underseasoned.
I`m glad you found the other crack,,and must say , the physical similarities in the cracks and location, along with the obvious wider weld nearing the bottom, lead me to feel there was still a fit issue (gapped). A gap could have been opened up during the tacking process , and the welder, rather than reworking the tacks, could have assumed he could make the weld.
On another theory: Looking at the cracks enlarged, show movement, or seperation of the two pieces at the crack, indicating physical stress relieving itself. If by chance the firebox and air manifold were not 90 degress to each other (perhaps indicating warping) then there would be a gap at some point where the two needed to be tacked together. I noticed a dent in the manifold of the last picture you posted,,,this could have been a result of using a spreader tool to close a gap before welding off (could be a weld close to the dent and possibly a dent in the right side manifold in a similiar location) This could be indicative of applying physical stress at the identical points of failure. Hhmmm. Thermal stress from seaming gap,,,mechanical stress from applied force,,, thin walled tubing for heat conductivity to heat air,,, combined with the air quenching flow inside the tubing while the outside is exposed to the firebox temps= unsupported theory :roll:
From my view point, I`d offer for argument each point,, if you indeed meet with opposition.