Before making electric heat tracing design decisions, engineers should confirm with their cable manufacturers that the sheath temperature data provided for their cables is the result of using the plate test. Additionally, engineers should be mindful of the several factors that can influence the sheath temperature. These include:
  • Heating Cable Diameter. With a larger diameter, mineral-insulated heating cable, the sheath temperature will be lower.

  • Ambient Temperature. The environment and temperature surrounding the area where the pipes will be installed.

  • Type, Quantity and Condition of Insulating Material. The amount and type of insulation used around the pipe can drastically impact the sheath temperature. Insulation should be in good condition for maximum performance.

  • Pipe Design. A single flow path design will offer a more consistent temperature because there are fewer factors throughout the installation that can impact the temperature.

  • On/Off Control. The methodology used to turn the pipe on and off can impact the temperature.

  • Reduced Voltage. Engineers should consider a small, step-down low voltage transformer to reduce the voltage supplied to an mineral-insulated heating cable and, consequently, reduce the sheath temperature to ensure heating cables do not produce more heat than required.
 

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