Heat tracing is a broad term that refers to the application of radiant heat input to piping systems via tubing attached to the pipe’s exterior. Heat tracing is a required process step. Pipes carrying fluids with higher temperatures than the ambient temperature will lose heat to the environment. Insulation is one method of reducing this loss. However, insulation is not completely foolproof. To compensate for the heat loss, small-bore steam pipes or electrical wires (referred to as heat tracers) are connected to the parent pipe. This system is known as piping heat tracing. Other applications for heat tracing include:
Keeping the process fluid at the proper temperature.
- Freeze defense.
- Keeping the fluid viscosity constant.
- Snow and ice removal
Types of Pipe Heat Tracing / Heat Tracing
Heat tracing is classified into two types:
- Tracing of Fluid Heat or Steam and
- Tracing with Electricity
To maintain the process fluid at the desired temperature, steam is circulated through tubes that run alongside the pipes in the steam tracing of piping. Other fluids, such as organics and glycols, can be used as tracing fluids in the design of a heat tracing system. However, as listed below, there are several advantages to using steam as a heat tracing fluid:
- When compared to other fluids, the cost of producing steam is lower. As a result, steam tracing is cost-effective.
- The cost of maintenance is also low. Once the steam tracing network is in place, maintenance costs will be reduced.
- Steam tracing of piping saves a lot of energy.
- Pipe Steam tracing quickly heats the process fluid.
- Steam does not require any pumping.
- Temperature control is critical in steam tracing.
In contrast, in the piping system’s electric tracing an electrical heating element transfers heat into the process fluid while running in physical contact along the pipe length. Normally, heat is generated in an electrically resistive element. Other effects, such as impedance, induction, skin conduction, and so on, can be used in electrical tracing. Cable heat tracing is another name for electrical heat tracing.
Heat Tracing Cable for Pipes
The following parameters are used to determine the best heat-tracing cable for electrical tracing:
- Heat is required.
- The temperature outside.
- Material for a pipe.
- Maximum exposure and temperature maintenance
- Supply voltage tolerance and voltage drop on feeding cables
- Voltage of service.
- Classification of Areas
- The Chemical Environment
- Margin of Design
Steps in Heat Tracing Design
The steps for designing a pipe heat tracing system are as follows:
- Heat loss from the pipe or equipment is calculated.
- Adjust the insulation system’s heat loss.
- Correct the heat loss while taking wind speed and additional safety precautions into account (margin).
- As a result, this calculated value will be used as input for the design of a heat tracing system. To maintain the required heat (temperature) in the process fluid, the heat tracing system should add at least that much heat to the piping system.
Heat tracing instrumentation
As process conditions dictate, in-line instruments may also be required to be heat traced. In that case, Piping must provide all other instruments with steam supply and condensate collection manifolds. The separation between Piping Traced Instruments and Control Systems Traced Instruments will correspond to the separation between the two departments.