How to effectively prevent local overheating of electric heat tracing

Local overheating of electric heat tracing is a high-frequency hidden danger in pipeline operation and maintenance. At the least, it can cause aging of cable insulation layers, and at worst, it can melt and break pipelines, leading to sparking and ignition. Improper material selection and temperature control during construction can cause various operational hazards. By standardizing construction and operation maintenance based on working conditions, we can avoid heat accumulation and temperature rise issues from the source, ensuring the safe operation of the heat tracing system.

Standardize the wiring and laying methods to eliminate man-made heat accumulation issues. The self-regulating heating cable must not be folded, crossed, or overlapped for wiring, as this can lead to resistance variations in the overlapping areas, resulting in local power surges and temperature spikes. The construction should uniformly adopt parallel pipe-fitting wiring, with elbow valve bodies appropriately extending the wiring, and allowing for slack margins. Wiring should not be bundled together. Additionally, it is prohibited to tie the heating cable tightly against high-temperature welds or protruding points on pipes, as local heat accumulation can easily exceed the temperature tolerance limit of the cable, causing overheating and damage.

Match the model and power according to needs to prevent model mixing and overload. It is strictly prohibited to mix and match different specifications of tracing bands, such as low-temperature, medium-temperature, and high-temperature, in the same power supply circuit. Different core resistances can lead to branch overheating imbalance. For small-diameter civilian pipelines, low-power tracing bands are sufficient. For large-diameter high-temperature medium pipelines, match the constant power dedicated cables according to needs. Do not use small pipelines to carry high-power tracing bands. For explosion-proof high-temperature conditions, it is forbidden to replace high-temperature armored tracing bands with ordinary tracing bands, as insufficient rated temperature resistance can easily lead to sustained overheating.

Strictly control the length of the circuit laying to avoid abnormal heating due to pressure drop at the end. Each type of heat tracing belt has a rated maximum circuit length. Overlength wiring will cause unstable line current, excessive temperature difference between the beginning and end, and severe local overheating at the wiring terminals. 220V self-regulating heat tracing strictly follows the rated meter length for shunt distribution. For excessively long pipe networks, split into multiple independent circuits, and individually configure air switches and residual current devices. It is prohibited to connect extension cables without authorization. Non-standard connectors will increase impedance, and after power-on, the connector points will continue to overheat.

Ensure proper insulation and sealing during construction to avoid the risk of stagnant heat accumulation. If the outer insulation cotton of the heat tracing belt is too thick and has zero breathability, coupled with a tightly sealed waterproof protective layer, heat cannot dissipate, forming a sealed high-temperature area. Select standard-thickness closed-cell insulation materials, with the insulation layer fitted with appropriate tightness, and avoid multiple layers of wrapping. For outdoor pipeline insulation, prevent water ingress and moisture, as damp insulation will have poor thermal conductivity, causing heat accumulation and unable to dissipate, which can lead to localized overheating and aging of cables.

Improve intelligent temperature control and management to avoid all-weather no-load heating. Direct power-on without temperature control is the main cause of overheating. All heat tracing circuits must be equipped with pipe wall temperature measurement and control devices, relying on pipe wall temperature to start and stop power supply, rather than ambient temperature measurement. Set standard start and stop temperatures, install overtemperature power-off protectors for high temperature conditions, and automatically cut off power when temperature exceeds the limit. Power off in time during seasonal changes, and shut down heat tracing during summer and warming weather to avoid no-load dry burning and overheating.

Ensure proper protection of connector fittings and standardize the management and control of power distribution operation and maintenance. The wiring terminals should be pressed and fastened to avoid false connections, sparking, and heating. Select original factory-matched waterproof junction boxes to eliminate the high impedance of non-standard fittings. Regularly inspect the temperature of connectors and bends, and clean the cables of surface debris and insulation buildup. Replace cables with abnormal aging resistance values in a timely manner to prevent uncontrolled heating and the formation of fixed overheating points.

To prevent local overheating, it is crucial to manage and control the four key points: wiring, length, temperature control, and insulation. By adhering to construction standards and implementing precise temperature control, we can mitigate high-temperature hazards, extend the lifespan of the heat tracing belt, and ensure stable and safe pipeline anti-freezing heat tracing.