71. Which of the listed procedures is the most important factor to take into consideration when making repairs to the refractory surrounding the burner openings?

Maintaining the original refractory cone angle is critical for proper burner air/fuel mixing, flame shape, and protection of boiler components. While crack filling, surface smoothness, and material type are important, preserving the original burner design geometry is the primary concern, as deviations can lead to poor combustion, hot spots, and tube damage. Boiler and burner manufacturers specify this geometry as part of the certified design, and repairs should maintain it unless formally approved.