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What is pipe heat tracing
What is pipe heat tracing

What is pipe heat tracing

What is pipe heat tracing?

Pipe heat tracing is a constant temperature or heating method used to keep materials at a certain temperature to prevent crystallization and solidification of materials in the pipe or to meet process requirements. In production practice, some mediums that are easy to condense, such as crude oil and heavy oil, will even solidify and affect production due to temperature decreasing and viscosity increasing gradually during pipeline transportation. Therefore, thermal insulation measures must be taken to maintain a certain temperature of materials when transporting such media.

Type of heat tracing system

The heat tracing system can be divided into two categories, electric and fluid. The fluid heat tracing system uses the heating medium under high temperature to transfer heat to the pipeline. Fluids are typically contained in tubes or small tubes connected to the tracked pipe. If the steam is a heat tracing fluid, the condensate will either return to the boiler or be dumped. If an organic heat transfer fluid is used, it is returned to the heat exchanger for reheating and recirculation. Generally, the heating of the heat tracing fluid can be provided by the combustion of waste heat, fossil fuel, steam or electricity of the process flow.
The electric heat tracing system converts electric energy into heat and transfers it to the pipeline and the fluid contained therein. At present, most commercial electric heat tracing systems are of resistance type and are in the form of cables placed on pipes. When the current flows through the resistance element, the heat generated is proportional to the square sum of the current and the resistance of the element to the current flow. Other dedicated electric heat tracing systems use impedance, induction and skin conduction effects to generate and transfer heat.

Type of heat tracing system

What is steam tracing?

Steam tracing is to apply steam heat to pipes and vessels to maintain the required process temperature, antifreeze, viscosity control or obtain temperature control points in the fluid, so as to enable chemical interaction in the process.
Steam tracing is usually accomplished by running steam lines that are in direct contact with the pipes or vessels to be heated.

Demand for steam tracing

The working principle of steam tracing is very simple. When the product temperature in the pipe is higher than the surrounding air, the heat will be transferred from the product to the surrounding air through the pipe wall.
This heat loss will cause the temperature of the product to drop. Pipe insulation will significantly reduce the heat loss rate, but unfortunately, no insulation is 100% effective.
Steam is a very effective heat carrier, and there is a fixed relationship between its pressure and temperature. It can transmit heat over a long distance and release heat at a constant temperature.
In order to compensate for the heat loss of the product pipeline, the small diameter steam pipeline or tracer is connected to the product line. The heat generated by steam enters the product line and replaces the lost heat. The heat transferred and the product temperature can be easily controlled by a simple self acting control system. The same type of control can also be used for winter applications. Only when the ambient temperature is lower than the predetermined level, can steam enter the tracing line.

In order to find the leaking part, the insulation layer of hundreds of meters of pipe must be removed. The cost is huge and also related to scaffolding. Therefore, please keep this in mind and ensure that the steam tracing is installed correctly.

Type of steam tracing

  • Jacket – For ultra critical applications, the product temperature must always be high. Steam jacket can also be used for fast preheating of pipes.
  • Critical – Here, steam tracing is used to maintain the temperature of the product, which will cure or deteriorate if it is below a predetermined level.
  • Non critical – tracking is used to maintain the product viscosity at the optimum pumping level.
  • Winterization – ensure that the pipeline will not be damaged due to freezing under severe weather conditions.
  • Instrument – small diameter steam tracing pipe, usually 10mm, used to protect flowmeter, control valve, sampling station, pulse pipeline, etc.

Determine heat loss rate

To select the size and number of steam tracing pipes required for a particular application, the heat loss rate of the product pipe must be determined under the worst design conditions.
This heat loss rate depends on the difference between product temperature and ambient temperature. Other factors, such as thermal conductivity of insulation, ambient wind speed and emissivity of insulation surface, will affect this loss rate.

Size and length

The most common steam tracing diameters are 3/8-inch (9.52mm) and 1/2-inch (12.7mm) OD copper or stainless steel tubes. 5/8-inch (15.88 mm) and 3/4-inch (19.05 mm) OD tubes were used; However, it will cost more. 3/8-inch pipes are more likely to be clogged by sediment and/or debris, so they are used less frequently. Copper is preferred because of its heat transfer characteristics, while stainless steel shows better resistance in corrosive environments.
Advantages of steam tracing compared with other methods
Although the advantages of each method can be debated, the following table shows the relative advantages and disadvantages of each system.
Due to the rising energy costs, one of the key areas that the factory needs to focus on is the reliability and energy efficiency of the tracer system. The high available heat content of steam provides many advantages over the use of hot fluids for heat tracing, and is much more efficient than electrical heat tracing.
As steam is mainly composed of water, it has little impact on the environment when it leaks into the atmosphere. It is estimated that the cost of cleaning up a litre of ethylene glycol may be as high as $5000.00. This cost includes clean-up, reporting, and documentation required when a spill occurs at an industrial site. Steam is intrinsically safe, making it a practical option for most industrial applications where ignition sources must be minimized.
For these reasons, in most industrial and process applications, the use of steam tracing is still the first choice for temperature maintenance.

Comparison of steam tracing and other methods

Steam Hot fluid Electricity
Cost of fluid Low Middle High
Cost of compensation Low Middle High
Cost of maintenance From Low to High depends on maintenance practices Middle Low
Temperature control High Middle High
Range of temperature Middle High Middle
Length of tracer Middle Low High
Intrinsic safety Yes Yes No
The energy efficiency High Middle Low
Freezing up potential Yes No No
Rate of heating up High Middle Low
Need to pump No Yes No

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