Estimate the heat loss from an insulated or bare pipe and the value of adding insulation. Enter the pipe size, fluid and ambient temperatures, insulation material and thickness, cladding, wind and running hours, and the calculator gives the loss per metre and total, the outer surface temperature with personnel and condensation checks, the annual energy and cost, and a table comparing every standard thickness.
What it gives you
- Heat loss or gain per metre and for the pipe length
- Surface temperature with a 60 °C touch-limit check for hot lines and a dew-point check for chilled lines
- Seven insulation materials with conductivity evaluated at the mean temperature
- Annual kWh and cost, and cost avoided against bare pipe
- Thickness comparison table from bare to 150 mm
Method and standards
The model is steady-state conduction through cylindrical insulation with combined convection and radiation at the outer surface, following the ISO 12241 and ASTM C680 approach. Convection uses the ISO 12241 simplified correlations for still air and wind; radiation uses the surface emissivity. The pipe contents are assumed at the stated temperature and the inside film resistance is neglected, which is conservative for liquids and steam. Use the manufacturer's declared conductivity for the actual product.
How to use it
- Enter pipe size, temperatures, material and thickness.
- Set cladding, wind and, for chilled lines, the ambient RH.
- Compare thicknesses in the table and read the annual cost.
Questions engineers ask
- How do I find the economic thickness?
- It is the thickness where annual heat cost plus annualised insulation cost is lowest. The table gives the heat-cost side; add your installed cost per metre for each thickness.
- Why does bright aluminium cladding run hotter?
- Low emissivity radiates less heat, so the surface sits at a higher temperature even though total loss is slightly lower.
- Is it suitable for chilled water?
- Yes. Enter a fluid temperature below ambient and the ambient RH, and the tool checks the surface against the dew point.
Need this calculation done properly, with a signed-off calculation pack or FEA behind it? Forgepoint provides mechanical design, analysis and pressure equipment engineering from Manchester, UK-wide.
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