What is calculated?
In radial conduction, area increases with radius. The diameter ratio therefore appears logarithmically in resistance.
Equations
Rλ = ln(da/di)/(2πλL)
Q̇ = ΔT/Rλ
Fluid dynamics & thermodynamics · preliminary design
Heat loss through pipe insulation
Determine radial conductive heat loss through cylindrical insulation.
IJ 5
02
Results
Enter values and run the calculation.
Application and limits
Compare insulation thicknesses and estimate distribution losses.
Homogeneous-insulation conduction only; films, radiation, pipe wall, supports and moisture excluded.
Frequently asked questions
Why surface temperatures?
The entered difference is across insulation; fluid and air temperatures require extra film resistances.
Does twice the insulation halve loss?
No; cylindrical geometry makes the relation logarithmic.
Technical basis
Dubbel, thermodynamics, heat transmission through pipes (local source, 2026-09-09).
The source supports the equation structure; this calculator does not claim a complete standards verification.