What is Electrical Heat Tracing(EHT)?

Electrical Heat Tracing is an engineered system designed to maintain or protect process piping, equipment, vessels, and instruments at defined temperatures and within the specified design criteria.

Electric cables are used for trace heating and to maintain temperature of non-flowing fluids by replacing the heat lost through thermal insulation on pipes, vessels and associated equipment.

A self-regulating polymer within the heat tracing cables controls the wattage(heat) of the element. When the outside temperature drops, more wattage will be supplied to the cables to generate heat to bring the equipment back to the required temperature. The opposite is true for when the temperatures rise as well.

There are two principles of Heat Tracing, Electrical and Heat Transfer.

There are three modes of heat transfer or heat loss:

• Conduction
  Transfer when bodies are in contact i.e., Standing barefoot on a cold floor.
• Convection
  Transfer by movement of gases or liquids or migration of molecules i.e., The “wind chill” factor.
• Radiation
  Transfer through electromagnetic waves i.e., Feeling the heat of the sun on your face.

If a Voltage is applied to a Resistance, Current would flow and Power would be dissipated.

E = I • R

P = I • E (Easy as a piece of pie)

where      I = Current

              R = Resistance

              E = Volts

              P = Power

Ohm’s Law is the basic operating principle of heating cables.

Power dissipated in the form of thermal energy = HEAT!

Everyday examples: Toasters, Iron, Light bulbs, Electric range, Heating cables.

To summarize, power output of the electrical cable replaces heat lost from conduction or convection.

Examples of Electrical Heat Tracing Application are tank heaters, pipe heat tracing (for freeze protection & temperature maintenance), roof and gutter de-icing on roofs, control and monitoring (power distribution panels), snow melting for ramps and driveways, and longline heaters.

The oil and gas industry are heavily reliant on heat tracing cables and technology as if the outside temperature is too cold, the oil in pipes might freeze and cause the oil flow to be stuck and thus heat tracing cables serve the purpose of wrapping around the oil pipes to produce heat and maintain the temperature of the oil.

EHT cable technologies include self-regulating, power limiting heating, mineral insulated and skin-effect heat tracing (STS).

Due to heat tracing cables self-regulating properties, they can be used to maintain specific temperatures. As an example, water tanks or pipes can be heated and maintained at the required temperature.

As the leading provider for EHT, Supermec relies on nVent Raychem for its self-regulating cables (SR)and power- limiting (VPL) cables.

nVent Raychem is the inventor of SR cables which are cut to length capability. The cables have regulated power output, lowering in operating cost and uniform pipe temperature. Furthermore, the cables have unconditional T-rating, safe and easy system design. They are cross linking technology with increased product life and highly reliable. Lastly, no overheating at cross-over which makes installation faster and easier.

At low temperature with many conductive paths, the nVent Raychem self-regulating cables will allow higher level of current to flow between the bus wires.

At high temperature when the polymer expands, the nVent Raychem self-regulating cables reduce the number of paths thus, electrical resistance rises hence heater reduces power output.

nVent Raychem power-limiting cables have coiled resistor alloy heating element wrapped around parallel bus wires. Resistance increases with temperature (PTC effect). PTC effect results in decrease in power output at elevated temperature. This allows the VPL to cross over itself without damage from overheating. It can also withstand temperature continuous to 260°C and can maintain up to 235°C.

Summary

As an expert in the field of heat tracing with many years of experience and having completed various large-scale projects. Supermec provides both constant wattage and self-regulating trace heating systems. You may view our range of nVent Raychem heat tracing cables here. Get in touch with our friendly electrical heat tracing experts at sales@supermec.com or you can drop us a call at +65 68619522 to find out how we can assist you with your heat tracing needs and install a heat tracing system to help your business objectives today.