Heat Tracing Wrapping Factor

Heat tracing wrapping factor when heat loss from pipe or tube is higher than cable capacity

When heat loss from pipe or tube is higher than the capacity of the heat trace cable, the cable must be spiral-wrapped around the pipe or tube.

The "heat loss - cable output" ratio can be calculated as

HR = Q_hl / Q_t (1)

HR = "heat loss - cable output" ratio

Q_hl  = heat loss from the insulated pipe or tube (W/m, Btu/h ft)

Q_t = heat output from the heat trace (W/m, Btu/h ft)

If the "heat loss - cable output" ratio - HR - is larger than one, the cable must be wrapped. The pitch - distance between spirals - can be estimated with the diagram below.  

Example - Heat Tracing

The heat loss from a 4" pipe is estimated to be three times (HR = 3) the heat output capacity of the tracing cable. The pitch - the distance between each spiral - can be estimated as indicated in the table below to 5-6 inches (125-150 mm).

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