Because the throat entry area is continuously exposed to direct, high-velocity flame contact, it handles the most aggressive thermal stress and cycling within the furnace chamber. During routine seasonal turnarounds or scheduled fireside cleanouts, maintenance teams should check the throat area for deep structural cracking, crumbling joints, or advanced spalling (surface chipping). If fragments break off or erode significantly, the altered dimensional shape will disrupt the burner’s air velocity and allow intense radiant heat to warp the front inner door assembly, indicating that a replacement boiler refractory tiles installation is urgently required.