Pipe Insulation Thickness

Required thickness from cylindrical conduction at a target surface temp.

Run the calculator

Example

You enter

Pipe OD (in) 1
Pipe surface (°F) 250
Ambient (°F) 75
Outer surface limit (°F) 120
Insulation k (BTU*in/hr*ft²*F) 0.27

You get

Required thickness 2.61 in
R2 (in) 3.11
R1 (in) 0.5

Details, formula, and sources

Heat loss / gain through pipe insulation: Q = (2π × k × L × ΔT) / ln(r2 / r1) for cylindrical insulation. Surface temperature compared against condensation / safe-touch limits.

ASHRAE Fundamentals by name; ASTM C680 for surface-condition calculation.

ASTM C680 licensed; principles free in published engineering texts.

Estimate. AHJ and licensed mechanical contractor govern. ACCA Manual J / D / S supersede rules of thumb.

Field names used by the API: pipe_od_in, surface_temp_F, ambient_F, surface_limit_F, k_btu_in_per_hr_ft2_F, thickness_in, r2_in, r1_in

Insulation k-value data/hvac/insulation.json keyed to materialmanufacturer + public engineering reference
Outside-film coefficient 1.65 BTU/(hr × ft² × °F) horizontal pipeengineering practice