Insulation Thickness

Insulation thickness

Preliminary. This is a steady heat-loss estimate. It needs engineering review before anyone uses it for personnel protection or for a thickness specification.

Formula

Do = Di + 2 × t

Rins = ln(Do / Di) / (2 × π × k)

Rsurf = 1 / (h × π × Do)

q = (Tp − Ta) / (Rins + Rsurf)

Ts = Ta + q × Rsurf

Di is the pipe outside diameter. t is the insulation thickness. k is the conductivity you enter. h is the surface coefficient you enter. Tp is the temperature of the metal outside surface. Ta is ambient. q is the heat loss per metre of pipe. Ts is the outside surface temperature. Bare pipe has no insulation resistance, so its surface temperature is Tp.

The metal wall and the fluid film are not included. k is taken as constant. The target, when you use one, is the number you type. This page does not look up a material conductivity.