Heat Tracing of Piping Systems
Pipe Tracing or heat tracing is commonly used to ensure that process, fluid, or material temperatures within pipes and piping systems are maintained above ambient temperatures during static flow conditions along with providing supplemental freeze protection in certain applications. One of the most common applications for electric heat tracing is to ensure the prevention of freezing of pipes. The most efficient and cost-effective system for freeze protection of pipes is to use self-regulating electric heat trace in conjunction with an ambient temperature sensing system.
Electric heat trace can be used to provide consistent temperature in pipes and tanks of all sizes in many different applications. Thermally protected pipes can keep product at a constant temperature while being transferred to different process through pipes and can reduce the tank heating costs as the incoming material does not create a thermal drag on the process.
Heat-tracing systems can be divided into two broad classes, electric and fluid.
Fluid/ Steam heat tracing
Fluid heat-tracing systems utilize heating media at elevated temperatures to transfer heat to a pipeline. The fluid is usually contained in a tube or a small pipe attached to the pipe being traced. If steam is the tracing fluid, the condensate is either returned to the boiler or dumped. If an organic heat-transfer fluid is employed, it is returned to a heat exchanger for reheating and recirculation. In general, heating of tracing fluids can be provided by waste heat from a process stream, burning of fossil fuels, steam, or electricity. Low cost and low maintenance costs are the major advantage of steam tracing. Since Pipe Steam tracing heats up the process fluid quickly, it is highly energy efficient.
Steam tracing is very simple in its principle of operation. When a product in a pipeline is at a higher temperature than the air surrounding it, heat will pass through the wall of the pipeline from the product to the surrounding air.
This heat loss will cause the temperature of the product to fall. Insulating the pipeline will significantly lower the rate at which heat is lost, but unfortunately, no insulation is 100% efficient.
Steam is a very efficient carrier of heat with a fixed relationship between its pressure and temperature. It can transport heat over long distances and gives up its heat at a constant temperature.
Electric heat-tracing also known as cable heat tracing convert electric power to heat and transfer it to the pipe and its contained fluid. The majority of commercial electric heat-tracing systems in use today are of the resistive type and take the form of cables placed on the pipe. When current flows through the resistive elements, heat is produced in proportion to the square of the current and the resistance of the elements to current flow. Other specialized electric tracing systems make use of impedance, induction, and skin conduction effects to generate and transfer heat.
Electric heat tracing often uses many cables around the pipe to provide heat flow from all directions. This configuration also increases reliability, since heating can continue even if one of the cables is damaged, providing time for maintenance personnel to perform the required reparations.
Modern electric heat trace cable has a self-regulating design, which adjusts the heat output as needed. Conductive elements are embedded in a polymer that expands and contracts in response to temperature
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