Ceramic Ferrule For Waste Heat Boilers

The waste heat boiler (WHB) is arguably the most fragile part of an sulfur recovery unit (SRU) and is subject to sudden and very costly failure. The most common failure is the tube to tubesheet joint where temperature can become unacceptably high, causing the welds to fracture and the joints to fail. To solve this problem, this region of the WHB is protected by ceramic ferrules inserted a short distance into the tubes and which usually also cover the complete face of the tubesheet.

Ceramic Ferrule Features

  • Corrosion resistance against high temperature acid gas
  • High refractoriness and load softening
  • Good strength and wear resistance
  • Good volume stability and creep resistance
  • Good thermal shock stability


  • Round ferrule & Hex ferrule
  • Two pieces ferrule for double security
  • Inlet of ferrule is like a horn, better fixed with refractory castable, reducing airflow resistance
  • The collar of ceramic ferrule is a whole part usually, we updated it to a moving part. There is a gap between ferrule and moving collar, when the airflow in the furnace generates thermal shock, it can form a certain movable space and offset part of line change of refactory castable


  Alumina Ferrule-1 Alumina Ferrule-2
Composition Al2O3 Al2O3+ZrO2
Bulk density g/cm3 2.9-3.1 3.2-3.5
Compressive strength MPa R.T. 100-120 200-250
Refractoriness ℃ 1800-1850 1790
Apparent porosity % 20-22 12-14
refractoriness under load ℃ 0.2MPa 1700 1650
Thermal shock stability1100℃×20min,water cooling >10 >30
Linear change on reheating 1600℃×3h % +/-0.2 +/-0.3

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