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Piping - Recommended Insulation Thickness

Recommended insulation thickness for heating systems like hot water and low, medium or high pressure steam systems.

To avoid heat loss and reduced system efficiency - pipe work in heating systems should always be insulated. Very hot systems, like hot water and steam systems should also be insulated to avoid potential personal injuries. 

The table below indicates recommended insulation thickness.

Piping - Recommended Insulation Thickness
Nominal Pipe Size
Insulation Thickness (inches)*
Temperature Range (oC)
50 - 9090 - 120120 - 150150 - 230
Temperature Range (oF)
120 - 200201 - 250251 - 305306 - 450
Hot WaterLow Pressure SteamMedium Pressure SteamHigh Pressure Steam
< 1" 1.0 1.5 2.0 2.5
1 1/4" - 2" 1.0 1.5 2.5 2.5
2 1/2" - 4" 1.5 2.0 2.5 3.0
5" - 6" 1.5 2.0 3.0 3.5
> 8" 1.5 2.0 3.0 3.5

* based on insulation with thermal resistivity in the range 4 - 4.6 ft2 hr oF/ Btu in (typical for mineral wool at room temperature)

  • 1 inch = 25.4 mm

Related Topics

  • Heat Loss and Insulation

    Heat loss from pipes, tubes and tanks - with and without insulation. Use of materials lke foam, fiberglass, rockwool and more.
  • Insulation

    Calculate heat transfer and heat loss from buildings and technical applications. Heat transfer coefficients and insulation methods available for reduction of energy consumption.

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