Pipes and Tubes - Recommended Insulation Thickness

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