Insulation Thickness — Companion Article

Open the tool: https://pipingdesigners.com/tools-training/insulation-thickness/

What this tool does

Insulation Thickness works out the heat loss per metre and the outside surface temperature for one layer of insulation on a pipe. It can also solve for the thickness that meets a target surface temperature or a target heat loss.

You type the insulation conductivity k and the surface coefficient h. No material table is stored.

When to use it

Use it for a first look at personnel protection, heat conservation, or comparing two thicknesses. Use your insulation specification or vendor software for the final figure.

Inputs

• Pipe outside diameter.
• Insulation thickness, or a target surface temperature or heat loss.
• Pipe (process) temperature and ambient temperature.
• Insulation conductivity k.
• Surface coefficient h.
• Units: metric or US customary.

How it works

The page adds two resistances, one for the insulation and one for the outer surface:

• Insulation: ln(Do / Di) / (2 π k).
• Surface: 1 / (h π Do).
• Heat loss q = temperature difference / (sum of resistances).
• Surface temperature = ambient + q × surface resistance.

To solve for thickness, it searches for the thickness that meets your target.

Understanding the result

Heat loss is per metre of pipe. Surface temperature is the outside of the cladding. A thicker layer always lowers both, but with smaller gains each step.

Engineering considerations

• k changes with temperature. Use a value for the mean insulation temperature.
• h depends on wind, surface finish and emissivity. Bright cladding runs hotter than dull.
• The pipe wall and inside film are left out. They are small next to the insulation.

Example

A 100 mm pipe at 200 °C in 20 °C air, with 50 mm of insulation, k = 0.05 W/(m·K) and h = 10 W/(m²·K), gives a heat loss and surface temperature. Ask the page to solve for that surface temperature and it returns 50 mm.

Standards/references (licensed vs interim)

The page uses textbook cylindrical conduction. No standard table is stored. Check k against the manufacturer’s data sheet.

Limitations/disclaimer

• One insulation layer only.
• No wall or inside film resistance.
• Steady state only.
• The result is preliminary and needs engineering review.

Use the tool

Calculate now: Insulation Thickness

Related tools

• Paint and Insulation, for insulation volume and cladding area (new tool, being added to the site).