Refractory Calculator

Calculate heat loss through furnace lining, cold-face temperature, and lining thickness — then select the right refractory material for your operating temperature and duty.

Heat Loss
W/m²
Through lining at steady state
Cold-Face Temp
< 50 °C
Safe touch temperature
Max Temp
1600 °C
Ceramic fibre blanket limit
Refractory Material Comparison
Material Max Temp Thermal Conductivity Density Best For
Ceramic fibre blanket 1260–1425°C 0.1–0.3 W/m·K 64–128 kg/m³ Electric furnaces, low-velocity gas
Ceramic fibre board 1260–1600°C 0.2–0.35 W/m·K 250–350 kg/m³ Vacuum furnaces, high erosion duty
Microporous board Up to 1000°C 0.02–0.04 W/m·K 200–300 kg/m³ Ultra-low heat loss, thin linings
Dense castable 1200–1600°C 0.8–1.5 W/m·K 1800–2200 kg/m³ High-abrasion, combustion zones
Insulating firebrick (IFB) 900–1400°C 0.35–0.6 W/m·K 700–1200 kg/m³ Structural linings, salt baths
Dense firebrick Up to 1600°C 1.0–2.5 W/m·K 1800–2400 kg/m³ Hearth, load-bearing, arch
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Calculator Functions

  • Steady-state heat flux through flat and cylindrical lining
  • Cold-face temperature prediction for safe touch assessment
  • Multi-layer lining analysis (hot-face + backup insulation)
  • Lining thickness optimiser — heat loss vs capital cost
  • Annual energy cost from heat loss calculation
  • Refractory material selector by temperature and duty

When Refractory Needs Replacing

  • Visible cracks deeper than 5 mm or through the hot-face
  • Spalling exposing the backup insulation
  • Cold-face temperature rising over successive months
  • Shell temperature hot spots above 120°C externally
  • Hearth slump or brick displacement under load
  • After a thermal shock event (emergency cooling, power failure)

Calculate Your Furnace Heat Loss Free

Enter lining dimensions and material — get heat flux, cold-face temperature, and annual energy cost in seconds.

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Related: Furnace Maintenance · Heat Treatment Calculators · Refractory Selection Guide