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# Pipes and Cylinders - Conductive Heat Losses

### Uninsulated Cylinder or Pipe

Conductive heat loss through the wall of a cylinder or pipe can be expressed as

Q = 2 π L (ti - to) / [ln(r/ ri) / k]                              (1)

where

Q = heat transfer from cylinder or pipe (W, Btu/hr)

k = thermal conductivity of piping material (W/mK or W/m oC, Btu/(hr oF ft2/ft))

L = length of cylinder or pipe (m, ft)

π = pi = 3.14...

to = temperature outside pipe or cylinder (K or oC, oF)

ti = temperature inside pipe or cylinder (K or oC, oF)

ln = the natural logarithm

ro = cylinder or pipe outside radius (m, ft)

ri = cylinder or pipe inside radius (m, ft)

### Insulated Cylinder or Pipe

Conductive heat loss through an insulated cylinder or pipe can be expressed as

Q = 2 π L (ti - to) / [(ln(r/ ri) / k) + (ln(rs / ro) / ks)]                          (2)

where

rs = outside radius of insulation (m, ft)

ks = thermal conductivity of insulation material (W/mK or W/m oC, Btu/(hr oF ft2/ft))

Equation 2 with inside convective heat resistance can be expressed as

Q = 2 π L (ti - to) / [1 / (hc ri ) + (ln(r/ ri) / k) + (ln(rs / ro) / ks)]                          (3)

where

hc = convective heat transfer coefficient (W/m2K)

## 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.

### • Thermodynamics

Calculate heat, work, temperature and energy. The thermodynamics of steam and condensate systems. Water and Ice properties.

## Related Documents

### Butane - Thermal Conductivity vs. Temperature and Pressure

Online calculators, figures and tables showing thermal conductivity of liquid and gaseous butane, C4H10, at varying temperature and pressure, SI and Imperial units.

### Conductive Heat Transfer

Conductive heat transfer takes place in a solid if there is a temperature gradient.

### Copper Tubes - Heat Losses

Heat loss from uninsulated copper tubes vs. temperature differences between tube and air.

### Copper Tubes - Uninsulated Heat Losses

Heat loss from uninsulated copper pipes - dimensions ranging 1/2 - 4 inches.

### Ethane - Thermal Conductivity vs. Temperature and Pressure

Online calculator, figures and table showing thermal conductivity of ethane, C2H6, at varying temperature and pressure - Imperial and SI Units.

### Ethylene - Thermal Conductivity vs. Temperature and Pressure

Online calculator, figures and table showing thermal conductivity of ethylene, also called ethene or acetene, C2H4, at varying temperature and pressure - Imperial and SI Units.

### Hydrogen - Thermal Conductivity vs. Temperature and Pressure

Online calculator, figures and table showing thermal conductivity of hydrogen, H2, at varying temperature and pressure - Imperial and SI Units.

### Insulated Copper Tubes - Heat Loss

Heat loss to surrounding air from insulated copper tubes.

### Nitrogen - Thermal Conductivity vs. Temperature and Pressure

Online calculator, figures and tables showing thermal conductivity of nitrogen, N2, at varying temperarure and pressure, SI and Imperial units.

### Oil Filled Tanks - Heat Loss

Heat loss from insulated and uninsulated, sheltered and exposed heated oil tanks.

### Oil Pipes - Heat Loss

Heat loss in W/mK and Btu/hr ft degF from oil tubes ranging temperatures 10 - 38 degC (50 - 100 degF).

### Pipes - Bare Surface Heat Loss

Heat loss vs. surface temperature.

### Pipes - Insulated Heat Loss Diagrams

Heat loss (W/m) from 1/2 to 6 inches insulated pipesĀ - ranging insulation thickness 10 to 80 mm and temperature differences 20 to 180 degC.

### Pipes - Insulated Heat Loss Diagrams

Heat loss (W/ft) diagrams for 1/2 to 6 inches insulated pipesĀ - ranging insulation thickness 0.5 to 4 inches and temperature differences 50 to 350 degF.

### Pipes Submerged in Oil or Fat - Heat Emission

Heat emission from steam or water heating pipes submerged in oil or fat - forced and natural circulation.

### Pipes Submerged in Water - Heat Emission

Heat emision from steam or water heating pipes submerged in water - assisted (forced) or natural circulation.

### Piping - Recommended Insulation Thickness

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

### Propane - Thermal Conductivity vs. Temperature and Pressure

Online calculator, figures and tables showing thermal conductivity of liquid and gaseous propane at varying temperarure and pressure, SI and Imperial units.

### Solids, Liquids and Gases - Thermal Conductivities

Thermal conductivity coefficients for insulation materials, aluminum, asphalt, brass, copper, steel, gases and more.

### Steam Pipes - Heat Losses

The amount of condensate generated in a steam pipe depends on the heat loss from the pipe to the surroundings.

### Steam Pipes - Heat Losses (W/m)

Heat losses from un-insulated steam pipes.

### Steel Pipes - Heat Loss Diagram

Heat loss from steel pipes and tubes - dimensions 1/2 to 12 inches.

### Thermal Resistivity and Conductivity

The ability of a material to resist flow of heat.

### Water - Thermal Conductivity vs. Temperature

Figures and tables showing thermal conductivity of water (liquid and gas phase) with varying temperature and pressure, SI and Imperial units.

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