How is insulation thickness calculated for a flat surface?

For a flat surface: thickness = k × (T_hot − T_surface) / q, where k is thermal conductivity of insulation, T_hot is process temperature, T_surface is desired surface temperature, and q is heat flux. The surface heat transfer coefficient h_out also plays a role: q = h_out × (T_surface − T_ambient).

How does pipe insulation calculation differ from flat surfaces?

Pipe insulation uses the cylindrical heat transfer equation with logarithmic radius ratio: Q/L = 2π(T_hot − T_ambient) / [1/(h_in·r_i) + ln(r_o/r_i)/k_pipe + ln(r_ins/r_o)/k_ins + 1/(h_out·r_ins)]. The curved geometry means more insulation material is needed per unit of thermal resistance.

What is a typical insulation thermal conductivity?

Mineral wool: 0.035–0.045 W/mK. Glass wool: 0.030–0.040 W/mK. Polyurethane foam: 0.022–0.028 W/mK. Calcium silicate: 0.055–0.070 W/mK. Aerogel: 0.013–0.020 W/mK. Lower k = better insulator.

What surface temperature is safe for personnel protection?

For personnel protection, maximum surface temperature should be ≤60°C (140°F) according to most industrial standards. Some standards require ≤50°C for surfaces accessible to workers. This prevents burns from brief contact.

Does the outer surface heat transfer coefficient matter?

Yes. The outer film coefficient h_out (typically 5–25 W/m²K) affects the surface temperature. Still air: ~5–10 W/m²K. Light wind: ~15 W/m²K. Forced convection: 20–50 W/m²K. Lower h_out means higher surface temperature for same insulation.

Ferramenta de Engenharia Gratuita

Calculadora de Espessura de Isolamento

Calcule a espessura de isolamento necessária para tubos e superfícies planas para atingir a temperatura de superfície alvo ou limitar a perda de calor.

Tubo e PlanoISO 12241#180

Resultados

Espessura de Isolamento Necessária

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Perda de Calor por m² (ou por m para tubo)

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Valor R do Isolamento

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Valor Global U

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Superfície Plana

Onde q = h × (T_surface − T_ambient) é o fluxo de calor da superfície externa.

Tubo / Cilindro

Para um tubo, o raio externo do isolamento r₂ é encontrado iterativamente para que a temperatura da superfície seja igual à alvo. Q/L é a perda de calor por metro de comprimento.

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