Pipe Heat Tracing
Choice of Cable
Usually for frost protection the cost efficient solution is to use TXLP on drum for very long lengths or standard TXLP/2 for runs up to 600 ft. When using TXLP on drum, it is important to take into account the maximum pipe temperature of 50 °C. In all cases a thermostat is recommended for proper temperature control. Install a thermostat with an external sensor, such as a WR284-50, this will ensure low power consumption and maintain a constant temperature. A GFCI is require by code in most cases.
Calculation of Required Heat Output
The type and length of cable required depends on the following data:
• Pipe dimensions
• Thermal insulation thickness
• The surrounding or ambient temperature
• Desired final temperature of the pipe
Unknown and non-controllable factors require a safety factor to ensure there is enough heat should there be an unplanned or unknown occurrence. A safety margin equal to a factor of 1.2 is not uncommon.
General Installation for pipes
The surface on which the heating is installed should be even without any sharp edges. The heating cable should be in good contact with the surface along the entire length of the pipe or surface of the vessel. Insulation should be protected against water intrusion.
To keep a constant and even temperature in pipes with a diameter less than 100 mm, it is normal to apply two cables along the length of the pipe. With a single conductor cable this is achieved by installing the cable in a loop along the length of the entire pipe. For pipes with a diameter larger than 100 mm, it is normal to install four cables along the pipe to ensure even heat distribution. Heating cables can also be installed spiraled on pipe. Should you decide to use twin conductor TXLP/2 cable, consult Britech for specific heat and voltage requirements. Series resistant heating cables can not overlap or cross each other.
Regardless of the type of cable, it should be fixed to the pipe every 30 cm with glass fibre tape. The cable should then be covered by aluminum foil tape along the entire pipe length. This foil or tape ensures good thermal contact/conductivity to the pipe. At valves and flanges the installation of cables should be arranged so that disassembly of these valves or flanges is possible without harming or cutting the heating cable.
The thermal insulation should be well protected against moisture and water intrusion. The ground wire of the heating cable must be connected to ground. Electrical insulation of the heating cable is measured before and after applying thermal insulation. GFCI’s are required in Canada. Do not exceed 15 amps per circuit where the cable is exposed to air or in contact with combustible materials. To reduce connected amperage loads pipe trace cables can be supplied up to 600 volt. Consult factory for custom cable needs.