Natural gas is valuable both as a clean source of energy and as a chemical feedstock. From exploration to distribution and final end-of-use location, natural gas requires multiple processing steps. These steps are required to be able to transport the gas over long distances, recover valuable components contained in the gas streams, and provide the means for the safe removal of toxic and environmentally harmful components contained in the gas. The offshore oil and gas industry offers many challenges for electrical heat tracing solutions to ensure secure workflow. After production, the gas is processed on a platform or at a land-based plant. Once the required specifications have been met, the sales or rich gas is compressed and transported by pipeline for further processing on land or directly to customers.
Offshore oil and gas applications for electrical heat tracing solutions can be divided into three areas:
Anti-icing or de-icing of escape passages, walkways, staircases and handrails. Icing is one of the biggest problems when operating in cold climate regions. Sea-water spray icing and atmospheric icing on platform surfaces, walkways and staircases can lead to slip and fall accidents.
Freeze protection for doors and escape hatches. Frozen door seals could create a severe safety hazard in case of an alert.
Frost protection for lay- down areas, helidecks, louvers, life boat davits and GPS and communication antennas must be provided to reduce safety hazards and ensure safe operations. Icing on antennas can impact communications and positioning of the vessel.
Water pipe freeze protection is critical for production and process water pipes, fresh/potable and waste water piping, and piping used for fire protection.
This second application is for the protection of process pipelines and equipment subjected to cold and artic weather. The process applications and the characteristics of the products are also reasons for heat tracing. Viscous products must be heated for transport. The formation of waxes (paraffins) may occur during the oil and gas production phases in some equipment (e.g. separators) on offshore production platforms. Electrical heat tracing can prevent wax and hydrate formation on separators which might impair the operation of instruments and create blockages of process piping. Additional Oil and Gas process equipment that requires heat tracing includes test separators, first and second stage separators, lift gas systems, compressors, scrubber lift gas modules, fuel gas systems and others. Besides the process equipment, these areas are also required to have freeze protection for operations and safety purposes, loading and unloading lines, gas vapor return lines, fire protection lines, strip and cleaning lines, fuel oil lines, storage tanks and vessels, deck and tank cleaning lines, engine room fuel and drip lines, cross-over lines, manifolds and safety showers.
Process temperature maintenance applications in particular require a properly functioning control system. While the heat tracing portion of the overall system can be considered the heart, it is the monitoring and control system that provides the brains of the operation. Since the heating system must be capable of operating at all times, redundancy must be built-in to ensure that if any part of the system fails or shuts down, it’s back up is capable of picking up the slack until the primary mode of operation can be repaired and restored. Data integration, communication and user interface preferences must also be considered when designing an integrated control system. The control system must be easily accessible, yet protected from unauthorized access. The operator should be able to access key parameters locally, while the system should be capable of transmitting key data via industry accepted data communication protocols.
3. Quarters Comfort
In these areas hot water temperature maintenance and frost protection of fresh water pipes plays an important role. Frozen water pipes will burst and damage the pipeline system. A reliable supply to the staff cannot be assured. The three levels of applying electrical heat tracing system depend on the ambient temperature, the product characteristics at the low temperature and the wind speed and directions. Typically nominal case region is around -15 °C. Cold region is around -30 °C and arctic region is around -45 °C. The DNV recommendation for winterization basic is:
Heating power capacity for anti-icing and de-icing shall not be less than:
300 W/m² for open deck areas, helicopter decks, gangways, stairways, etc.
200 W/m² for superstructures
50 W/m for railings with inside heating
These are the minimum heating output requirements. For individual cases, lower ambient temperatures and/or higher wind speeds will increase the heat loss due to convection of air, and the heating output shall increase accordingly. The factors below should be taking into account when designing the heating system: Snowfall in the area of operation, Ambient temperature, wind velocity in the area of operation and water source.
The Vessel’s superstructure surfaces and systems are to be heat traced or de-iced in accordance with the winterization plan considering: open deck area, gangways, stairways, superstructure areas subject to icing and railings. eltherm electrical heat tracing solutions are used to prevent freezing for a number of applications such as: exposed piping, tank vent, instrumentation, recirculation shell valves, overboard discharge and drainage. eltherm conducts Finite Element Analysis (FEA) simulation based on the environmental conditions to confirm and verify each design All products and solutions must generally be certified to DNV-GL, ABS, BV, TUV, ATEX and IEC Ex standards and required to be suitable for Marine and Oil and Gas Offshore hazardous and harsh environmental applications.
The proper design and implementation of an electric heat tracing system for offshore oil and gas applications is critical to ensure a safe, reliable and efficient operation. There are many different types and configurations of heating cable designs available, and involving a heat tracing supplier specialised in manufacturing the appropriate products and selecting the best solution should be considered. This important part of the project engineering should not be left to chance, because failures in the system could cause enormous costs and damages to the operator and owner of the offshore facilities. The harsh environment that all components of the heating system will be exposed to must also be considered, and material selection and workmanship of the heating cables is critical to ensure a long operational life-time.
The use of state-of-the-art design tools during the planning phase, including multi-dimensional modeling software that provides optimum layout and failure analysis, are vital to the successful implementation of a reliable and efficient system at a reasonable cost. The eltherm heating cable in combination with the individually planned and designed monitoring and control system represents an excellent solution for a reliable and efficient heating system.