Pipes and Tubes - Recommended Insulation Thickness

Insulation thickness of heating systems - hot water - low, medium and high pressure steam - systems

To avoid heat loss and reduced 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.

Recommended minimum Thickness of Insulation (inches)*
Nominal Pipe Size
NPS
(inches)
Temperature Range (oC)
50 - 90 90 - 120 120 - 150 150 - 230
Temperature Range (oF)
120 - 200 201 - 250 251 - 305 306 - 450
Hot Water Low Pressure Steam Medium Pressure Steam High 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

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