Bitumen Pipeline Heat Tracing Design: Thermal Oil Jacket vs Electric Heat Tracing

A correctly sized bitumen pipeline can still fail if the binder inside it becomes too cold to pump.

For this reason, hot-bitumen transfer systems should be designed as both hydraulic systems and thermal systems. Pipe diameter determines flow and pressure loss, while heat tracing and insulation determine whether the binder remains within a suitable operating range.

Two common approaches are thermal oil jacketing and electric heat tracing. Neither method is universally better. The correct choice depends on pipeline length, project utilities, operating temperature, system size, startup requirements and maintenance strategy.

What Is the Purpose of Bitumen Pipeline Heat Tracing?

The primary purpose of heat tracing is normally to compensate for heat loss and maintain the binder in a pumpable condition.

Heat tracing should not automatically be expected to heat a long pipeline full of completely cold or solidified bitumen rapidly from ambient temperature.

The design basis should define whether the system is intended for:

• Temperature maintenance during operation
• Standby temperature maintenance
• Preheating before startup
• Controlled reheating after shutdown

These are different thermal duties.

Why Hot Bitumen Pipelines Lose Heat

Heat leaves the product through the pipe wall, tracing or jacket system, insulation and external surface.

The total thermal requirement depends on:

• Bitumen temperature
• Temperatura ambiente
• Diâmetro da tubulação
• Comprimento do oleoduto
• Material isolante
• Espessura do isolamento
• Exposição ao vento
• Valves, flanges and supports
• Required warm-up time

A cold outdoor project in winter has a very different heat-loss profile from a short indoor transfer line in a tropical climate.

Oleoduto com revestimento de óleo térmico

A thermal oil jacket uses hot heat-transfer oil flowing through an outer jacket or dedicated tracing arrangement around the bitumen pipe.

The thermal oil receives heat from a thermal oil boiler or heater and circulates through the tracing circuit.

Vantagens

• Integrates naturally with sites already using a thermal oil boiler
• Suitable for tanks, pumps, valves and pipelines within one common heating network
• Can provide strong and stable indirect heating
• No high electrical heating load distributed along the pipe
• Useful for larger centralized bitumen systems

Considerations

• Requires thermal oil supply and return piping
• Requires circulation and balancing
• Additional valves and joints increase installation complexity
• Long branches require hydraulic design
• Leakage and expansion must be considered
• The boiler must have enough spare thermal capacity

Rastreamento de calor elétrico

Electric tracing cable is installed along the process pipe and covered by suitable insulation and weather protection.

Depending on the design, the tracing can use constant-wattage, self-regulating or other industrial cable technologies suitable for the required temperature range.

Vantagens

• No thermal oil supply and return circuit
• Easier zoning and individual temperature control
• Useful for short or isolated pipelines
• Convenient for pumps, valves and small auxiliary sections
• Can simplify installation where a thermal oil boiler is unavailable

Considerations

• Requires sufficient electrical power
• Cable and accessories must be rated for the operating temperature and environment
• Long circuits require electrical design and zoning
• Damage to tracing cable can create a local cold spot
• Electrical protection and temperature control must be properly designed

Thermal Oil vs Electric Heat Tracing

Step 1: Define the Operating Temperature

Before calculating heat tracing, define:

• Normal bitumen transfer temperature
• Minimum allowable pipeline temperature
• Maximum material temperature
• Standby temperature
• Expected ambient minimum

The required temperatures depend on the actual binder grade and process.

Do not use one fixed temperature for penetration bitumen, SBS modified bitumen, rubber bitumen and emulsion.

Step 2: Calculate Pipeline Heat Loss

The tracing system must at minimum compensate for the required steady-state heat loss under the design ambient condition.

A detailed calculation considers conduction through insulation and external convection and radiation.

Important inputs include:

• Pipe outside diameter
• Insulation thermal conductivity
• Espessura do isolamento
• Process temperature
• Temperatura ambiente
• Wind condition
• Comprimento do oleoduto

The result provides an estimated heat requirement per unit length and for the complete circuit.

A universal watts-per-metre value should not be applied to every project.

Step 3: Add Valves, Flanges and Pumps

Heat loss is not evenly distributed.

Valves, flanges, filters, pump casings, strainers and equipment interfaces have greater surface area or thermal mass and may require additional tracing.

Many pipeline failures begin at these components rather than in the middle of a well-insulated straight pipe.

Step 4: Divide the System into Heating Zones

A long transfer network should not necessarily operate as one uncontrolled heating circuit.

Useful zones may include:

• Tank outlet and pump suction
• Main transfer pipeline
• Filter and valve station
• Asphalt plant connection
• Circulation return
• Tanker unloading line

Zoning allows the operator to heat only the circuits required for the current operating mode.

Thermal Oil Circuit Design

A thermal oil tracing system requires more than a sufficiently large boiler.

The designer should evaluate:

• Available thermal oil temperature
• Required oil flow
• Supply and return pressure
• Pressure loss through each branch
• Balancing between parallel circuits
• Expansion
• Venting
• Drenagem
• Válvulas de isolamento

A distant pipeline may receive poor heating if the oil circuit is badly balanced.

For boiler-sizing principles, see:

Como calcular a capacidade do aquecedor de óleo térmico para tanques de armazenamento de betume

Electric Heat-Tracing Design

Electric tracing requires a coordinated electrical and thermal design.

Check:

• Required heat output
• Cable temperature rating
• Maximum exposure temperature
• Circuit length
• Power supply voltage
• Starting current where applicable
• Controller and sensor location
• Overcurrent protection
• Ground-fault protection where required
• Hazardous-area classification if applicable

The selected system must be suitable for the equipment’s environment and local electrical standards.

Temperature Sensors Must Be Positioned Carefully

A temperature sensor should represent the section the controller is intended to protect.

Possible control problems include:

• Sensor too close to the heating source
• Sensor installed where it does not represent the coldest section
• One sensor controlling several thermally different branches
• Poor contact between sensor and pipe

Large systems may require multiple temperature zones.

Insulation Is Essential

Heat tracing without effective insulation can waste substantial energy.

Insulation helps:

• Reduce heat loss
• Reduce fuel or electricity demand
• Maintain more uniform pipeline temperature
• Shorten warm-up time
• Protect the process from rapid ambient changes

Insulation joints around valves, supports and removable covers deserve particular attention.

Pipeline Diameter and Heat Tracing Are Connected

Larger pipes contain more bitumen and have more external surface area. Smaller pipes may reduce thermal mass but increase hydraulic pressure loss.

Therefore hydraulic and thermal design should be coordinated.

For pipe sizing, see:

Como calcular o diâmetro da tubulação de betume para uma usina de asfalto

Shutdown and Restart Must Be Designed in Advance

One of the most important questions is what happens to the bitumen remaining inside the pipe after production stops.

Depending on the system, the shutdown procedure may use:

• Continued heat tracing
• Circulation back to the tank
• Reverse pumping
• Gravity drainage
• Controlled line emptying

A system that relies on reheating a completely filled cold pipeline after every shutdown may require much more heating capacity and startup time.

Common Heat-Tracing Failures

Tracing Only the Straight Pipe

Valves, filters and pumps become cold spots.

Insufficient Insulation

The installed heat cannot compensate for excessive external loss.

One Zone for a Very Long Network

Some sections overheat while remote sections remain cold.

Undersized Thermal Oil Circulation

The boiler is hot but distant jackets receive insufficient oil flow.

Damaged Electric Tracing

One failed circuit can leave a hidden cold section.

No Shutdown Strategy

Bitumen cools inside valves, filters and low points before the next startup.

Which Method Should You Use?

Thermal oil is often attractive when:

• A central thermal oil boiler already exists
• Several tanks and pipelines share one heating network
• The project is large and centralized

Electric tracing is often attractive when:

• The line is relatively short or isolated
• Stable electrical power is available
• Independent temperature zones are desirable
• Adding thermal oil piping would be unnecessarily complex

Some projects use both methods: thermal oil for major process equipment and electric tracing for local valves, instruments or auxiliary lines.

Perguntas mais frequentes

Can heat tracing melt completely solid bitumen inside a pipeline?

That depends on the tracing capacity, pipe size, insulation, material condition and allowable heating time. Many tracing systems are primarily designed for temperature maintenance rather than rapid recovery from complete solidification.

Is thermal oil always better than electric tracing?

No. The correct method depends on existing utilities, system size, pipeline length, control requirements and lifecycle cost.

Does every bitumen valve need heating?

Valves in hot-bitumen service are potential cold spots and should be evaluated individually as part of the thermal design.

Can the same thermal oil boiler heat tanks and pipelines?

Yes, if it has sufficient total thermal capacity and the circulation network is correctly sized and balanced.

Conclusão

Bitumen pipeline heat tracing should be designed from heat loss and operating strategy rather than selected only by pipe length.

A sequência de engenharia é:

Process Temperature → Ambient Condition → Heat Loss → Tracing Method → Zoning → Insulation → Shutdown Strategy

FEITENG provides thermal oil heating equipment, electric heating solutions, heated pumps, valves and pipeline systems for complete bitumen handling projects.

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