Pipes - Insulated Heat Loss Diagrams

Heat loss (W/ft) diagrams for 1/2 to 6 inches insulated pipes - ranging insulation thickness 0.5 to 4 inches and temperature differences 50 to 350 degF. Based on metal pipes with fiber glass insulation (thermal conductivity 0.25 Btu/h oF ft2/in) and moderate wind conditions (20 mph) with 10% safety factor.

Insulation Thickness (inches)Pipe Size RangeTemperature Difference Range (degF)Heat Loss Range (W/ft)Notes
0.51/2 to 650 to 350Refer to diagramHighest heat loss
1.01/2 to 650 to 350Refer to diagramStandard insulation
1.51/2 to 650 to 350Refer to diagramStandard insulation
2.01/2 to 650 to 350Refer to diagramStandard insulation
2.51/2 to 650 to 350Refer to diagramStandard insulation
3.01/2 to 650 to 350Refer to diagramStandard insulation
4.01/2 to 650 to 350Refer to diagramLowest heat loss

Adjustment Factors

  • Indoor location: Reduce values by 10%
  • Mineral wool insulation: Increase values by 6%
  • Rigid cellular polyurethane: Reduce values by 30%

Unit Conversions

  • 1 W/ft = 3.41 Btu/h ft = 3.28 W/m
  • 1 oF = 0.555 oC

Assumptions

  • Material: Metal pipes with fiber glass insulation
  • Thermal conductivity: 0.25 Btu/h oF ft²/in
  • Outdoor conditions: Moderate wind (20 mph)
  • Safety factor: 10% included