Before applying the Heat Trace as a heating solution, it is important to understand what technology is involved.
Let’s understand the situations in which heating solutions should be considered. The temperature of a fluid/gas in a pipe can be critical to the operation of the plant. In the winter months, when we have lower temperatures, protection against freezing becomes essential, particularly in lines with little or no flow. Fluid temperatures may need to be maintained while they are stored or running through the factory piping.
Increasing and maintaining temperatures in the process piping is important for the operation of many industrial facilities. Selecting a heating system is generally not a quick and easy decision, as there are both short- and long-term cost and operational implications.
A heating system involves placing a heating cable in a pipe, applying insulation to the cable and pipe, and controlling the energy in the cable. Designing simple heating system designs is generally the best approach, which in turn keeps design, documentation, installation and operation easy to use and can even reduce costs.
Although thermal insulation reduces the loss of energy to the environment, this barrier alone may not be sufficient for the process, requiring the application of Heat Trace solutions to compensate for the loss.
How the heat trace works:
The heat trace is a system used to maintain or raise the temperature of equipment, pipes, vessels, tanks. Heating trace is achieved using a resistive cable installed on the wall. Current Heat Trace technology uses a self-regulating polymer that controls the power delivered to the process. When the ambient temperature drops, the polymer creates conductive paths that allow the current to flow and heat. When the ambient temperature rises, the conductive pathways start to separate, causing less current to pass.
Manufacturers have developed various thermal tracking cable technologies suitable for certain applications. The variety of thermal tracing technologies available on the market varies with respect to their maximum maintenance temperature and maximum power capacity of the circuit.
At a high level, technologies are categorized as series resistance or parallel resistance. Parallel strength technologies have advantages, such as being able to be cut to any length, field terminable, flexible and generally available on the shelf. Series resistance technologies have the advantage that they can be used for longer circuit lengths from a power source.
All of these developed thermal heating technologies have the primary objective of facilitating the flow of processes. Heat tracing can be used in several projects, and the cables that will be used depend on what the application is.
Types of cables for heat tracing systems:
Self-regulating cable: This type of cable offers the lowest cost, the low temperature usage range and the ability to cut and finish in the field. The current and power output of the self-regulating cable change with temperature. This type of cable has peak current, which can result in a shorter cable length per circuit. This cable is typically used for frost protection and thermal tracking up to 150 ° C.
Constant-wattage Cable: This type of cable offers medium cost, higher temperature range and cutting and termination capabilities in the field. The constant power cable has the advantage of always providing the same power throughout the circuit regardless of the outside temperature. This cable is typically used in industrial pipe temperature maintenance. Depending on the insulation of the cable cover, the thermal trace maintains temperatures in the range of 204 ° C.
Mineral Insulation Cable: This type of cable has a higher cost and a high temperature maintenance capacity. Normally, the mineral insulated cable is terminated at the factory and manufactured to the design lengths and power. This cable can have HDPE sheath insulation for increased chemical resistance, a bare copper sheath, or a stainless steel sheath for high temperature and chemical resistance. Temperatures above 1000 ° F (538 ° C) are attainable with stainless steel mineral insulation cable.
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How to dimension an Heat Trace System:
Heat trace cables need to be properly sized for each process. The cables have various power outputs, voltages and sheath materials. The cables are normally designed to work along the pipeline, the installation can also be done in a spiral, but in specific situations, since it makes the installation more complex. Valves, flanges, supports and other components with greater mass than the linear section of the pipe become heat sinks and require a greater concentration of cable in place to ensure compensation for additional heat loss.
Energy loss calculations are based on the thermal conductivity factor of the material applied in the thermal insulation, as well as its thickness, the largest temperature difference between the process and the environment and the total surface area.
ThermoFlow is a brazilian company that designs and supplies heat tracing systems. We have all types of cables, and we seek to understand the needs of each project, with fast, safe solutions that meet the costs of customers.