Long Pipeline Heating

Industrial longline heating heating is required to ensure that liquids are transported cost-effectively and safely over long distances.

Typical long line applications include:

  • Transfer lines between processing plants or to storage or transportation facilities.
  • Freeze protection or temperature maintenance of tank farms and piers for ocean transport
  • Condensation and coagulation prevention on filters, reddlers etc…

In the absence of longline heating, the following problems could result in significant environmental and property losses:

  • Liquids becoming too viscous
  • Gases condensing
  • Liquids freezing resulting in catastrophic pipe failures

The complexity of Longline pipe heat trace system comes from the need for long electrical circuit lengths, usually with a single electrical power supply point.
Longline heating applications have several challenges, such as:

  • Large pipe diameters
  • Elevation changes along the length
  • Remote locations
  • Lack of power availability along the length

For pre-insulated pipes, additional challenges include:

  • Alignment of channels
  • Lack of insulation at the pipe joints
  • Pulling long lengths of cable through the channels
  • Lack of accessibility of connection kits
Longline Heating – A Complete Heat Management System Approach

nVent Thermal Management offers a wide range of industry-proven longline heating solutions as a complete heat management system which includes the selection of appropriate pipe heat trace technologies, advanced control system technologies, and site services in addition to turnkey services.

Heat-Tracing System
  • Electric heat trace cables that maintain the temperature of non-flowing fluids by replacing the heat lost through the thermal insulation on pipes, vessels and associated equipment.
  • Control and monitoring solutions –to help maintain the temperature of the fluid through a heat traced pipe.
  • Components and accessories – items for making electrical connections and properly completing the installation, such as end terminations, glass tape and warning labels.
  • Engineering design services
  • Procurement and fabrication
  • Site services
  • Post installation services

We can supply the individual components, provide engineering design services and will even install and maintain the entire system.

When our advanced heat trace products are combined with our site services, you get an integrated solution that is strategically planned and executed for an optimum heat management system (HMS). By managing and executing all aspects of the heat trace system design and installation, we provide a single interface to your project team.

Various technologies allowing circuit lengths up to 25 km

Adding power supply points can drastically increase the cost of a heat tracing installation. Depending on the desired circuit lengths, we offer Long Line heating in various technologies:

  • nVent PYROTENAX Mineral-Insulated cables up to 5 km
  • nVent RAYCHEM polymer-insulated series resistance heat trace cables for medium to high temperature applications up to 5 km
  • nVent TRACER skin-effect tracing cables for very long pipelines up to 25 km
Customised Support to minimize the cost
  • Customized pipe supports
  • Customized power distribution systems
  • Optimized insulation systems and pre-fabricated/ pre-insulated piping systems
Advanced Control systems for adequate control & monitoring on Long pipelines

Since Long Line systems are constant wattage systems, the choice of an adequate control system is very important and can have significant impact on the performance of the system


The different technologies in our product bag dispose of a wide range of approvals showing compliance to ATEX, RTN, IECEx and many more industrial or national standards.

Design capabilities

nVent Thermal Management disposes of design centres all over the world which have the capability to extend the heat tracing design over multiple disciplines to ensure the optimum heat tracing system.
Our engineers have the possibility to use different software tools that are considered to be the leading standard in the industry, such as TraceCalc Pro or the complete 3-D design package TRACER Lynx .

Longline heating systems can be complex to design and install. nVent Thermal Management offers several technologies to choose from, thus providing the best cost optimization for your longline heating project. The longline heating technologies are:

Polymer Insulated Technology

nVent RAYCHEM Polymer Insulated (PI) series heating cables  are the appropriate solution when a single power source is needed and the circuit lengths exceed the ratings of conventional parallel cables for lengths up to 5km. Thanks to the use of PTFE in the inner and outer insulation the cables can:

  • Be used for temperatures up to 250°C (300°C intermittent), without polymer degradation
  • Be used when desired power is in the range of 30W/m.
  • Be easily installed and field terminated.
  • Resist aggressive chemical substances

Mineral insulated technology

nVent PYROTENAX Mineral Insulated (MI) heating systems should be considered when the associated temperatures and/or power outputs exceed the capabilities of polymer cables.


  • Very high power outputs up to 300W/m and more
  • Extreme exposure temperatures, such as 600°C and more.
  • Optional with HDPE or FEP for additional corrosion protection
  • Single conductor in multitude of sheath materials (Cupro-nickel, Stainless steel (AISI 321), Inconel 600 and Alloy 825)
  • Dual conductor in Alloy 825 only
  • Pre-terminated Mineral Insulated heating cables
  • Laser Welded connections to provide optimum quality

Skin-Effect Heat Tracing Systems Technology


RAYCHEM STS skin-effect heat tracing system is a versatile engineered heat management system that is ideal to deliver heat for medium to long pipelines up to 25km.

Applications include:

  • Material transfer lines
  • Snow and ice melting
  • Tank foundation heating
  • Subsea transfer lines
  • Prefabricated, pre-insulated lines

As the industry leader in single source responsibility for heat management systems, we offer Skin-Effect Tracing Systems as turnkey solutions.

Advanced Control Systems

nVent Thermal Management offers a number of RAYCHEM advanced control systems designed specifically for longline heating applications. The RAYCHEM control and monitoring products:

  • Allow for  customized power distribution systems, three-phase current monitoring and high current switching capabilities all of which result in a more reliable and optimized heating system
  • Are capable of sensing up to eight process temperatures for each individual control circuit
  • Allow the circuit to be controlled on minimum, average or designated temperature input
  • Include sophisticated control methods that provide monitoring of circuit integrity, performance and ground-fault current, and ground-fault protection

For certain specialized applications, nVent Thermal Management also offers fibre optic temperature sensing solutions to measure the temperature of the pipe along its length with 1 metre resolution and 1ºC sensitivity.

Optimized Heat Management System Ensures Safe Sulfur Transport at Large LNG Plant
Key Challenges

The Qatargas Sulphur Transfer Line project consisted of a 35 km, dual, 12 inch sulphur pipeline constructed to transfer molten sulphur from 11 producers to a sulphur pelletizer facility. Heat management system challenges included:

  • Tight range of allowable temperature from 125ºC to 145ºC for molten sulphur with a set point of 135ºC along the entire length of pipeline.
  • An outdoor large sulphur pipeline with significant weight, multiple flow paths, and vertical expansion loops every 150 m.
  • Capability to re-melt and re-heat solidified sulphur without causing overheating or overexpansion.
  • A 100% redundant heat management system for the pipeline.

To meet the needs of this challenging longline heating application, nVent Thermal Management employed the following heat management system:

  • Inherently safe nVent TRACER skin-effect heat tracing system which has high exposure temperatures and efficient heat transfer to the pipe.
  • State-of-the-art nVent RAYCHEM control and monitoring system with vacuum contactors.
  • Finite element analysis to determine the temperature profile of sulphur across the cross section of the pipe.
  • Fibre-optic based distributed temperature sensing system that provides dynamic pipeline temperature profile at each meter with 1ºC accuracy for the entire length.
  • Multi-power heat delivery mechanism with 70% of installed power for normal operating conditions and 100% of installed power for heat-up/re-melt conditions.
  • Multi-layer thermal insulation system with high temperature expanded perlite inner layer, load bearing closed cell foam outer layer and UV resistant jacket.
  • Full service procurement of materials, project management, construction and commissioning of the pipeline.

TRACER skin-effect heat tracing system, RAYCHEM control and monitoring system.


nVent Thermal Management’ ability to engineer and integrate multiple technologies with its expertise in construction and commissioning heat management systems resulted in a world-class, safe, reliable, and efficient heat trace sulphur pipeline with the following benefits:

  • The TRACER skin-effect heat tracing system not only minimized the number of circuits, but also resulted in better heat transfer and low temperature differential between the pipe and cable sheath, thus leading to a safer longline heating design.
  • The finite element analysis and RAYCHEM control and monitoring solutions ensured that the sulphur temperatures did not go outside the tight control temperature range under normal operating conditions.
  • The fibre-optic distributed temperature sensing system provided continuous monitoring of the temperature along the entire length of the pipe. This helped to locate hotspots along the length of pipe during the re-melting process and in turn avoided excessive pressure generated by melting sulphur.
  • Multi-power heat delivery mechanism and multi-layer insulation systems not only optimized the total operating costs of the longline heating system but also contributed to shorter re-melt duration.
  • By assuming total responsibility of the heat management system, nVent Thermal Management ensured that the project was completed on time, safely and to the satisfaction of the customer.

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