ASTM C680 (Heat-Loss Calculation)
ASTM C680 is the standard practice for calculating heat loss or gain and surface temperature of insulated pipe and equipment, using a one-dimensional steady-state heat-transfer model. It is the basis of most industrial insulation heat-loss software and lets engineers compare bare vs insulated performance and size insulation consistently.
ASTM C680 defines how to compute conductive, convective and radiative heat transfer through flat, cylindrical and spherical insulation systems given the layer conductivities, ambient conditions and surface emissivity. Its outputs are the heat-loss rate per unit area or length and the outer-surface temperature - the two numbers that drive both energy and personnel-protection decisions.
Because the method is standardised, results are repeatable and auditable, which is why insulation suppliers and energy auditors cite C680 (often via tools like NAIMA 3E Plus) when quantifying the savings from insulating bare or under-insulated equipment.
Related reading
Related terms
Heat Loss · Thermal Conductivity (λ) · Emissivity (ε) · U-value (Thermal Transmittance) · Surface Temperature · Economic Insulation Thickness · NDT (Non-Destructive Testing) · Personnel Protection (Surface Temperature)