Liquefied Natural Gas (LNG) Facility Electrical Construction, Instrumentation & Controls
Cryogenic Infrastructure With Consequence
Liquefied natural gas facilities operate at minus 260 degrees Fahrenheit, storing and transporting natural gas in liquid form at approximately 600 times the volume density of the gas phase. The electrical and I&C systems supporting LNG liquefaction, storage, and regasification must perform reliably at those temperatures and under the safety requirements that govern facilities handling large volumes of liquefied flammable gas.
Wikota Electrical Services brings cryogenic facility experience from the helium market, where operational temperatures and high-purity requirements exceed those of LNG service, to LNG electrical and I&C engagements. The instrumentation selection principles, thermal management requirements, and classified-area compliance practices developed in cryogenic helium work apply directly to LNG facility construction.
Liquefaction Facility Electrical and I&C
Refrigeration and Liquefaction Process Electrical
Natural gas liquefaction requires removing heat from the gas stream through refrigeration cycles using propane, mixed refrigerant, or nitrogen as the refrigerant medium. Refrigeration compressor electrical scope covers large motor MCCs, variable frequency drives for capacity control, intercooler and aftercooler fan electrical connections, and the medium-voltage distribution system supplying the refrigeration train. I&C scope covers refrigerant temperature and pressure monitoring throughout the refrigeration cycle, cold box inlet and outlet temperature monitoring, and the control system managing refrigeration compressor loading and liquefaction column temperatures.
Cold Box and Heat Exchanger Instrumentation
LNG cold boxes house the main heat exchanger and associated cryogenic piping in insulated enclosures. Instrumentation installed inside or adjacent to cold boxes must be rated for cryogenic service temperatures. Temperature measurement uses Type T thermocouples or platinum RTDs rated for low-temperature service. Pressure measurement uses diaphragm-sealed transmitters with fill fluids rated for the cold box operating temperature range.
LNG Storage Tank Electrical and Instrumentation
Tank Level and Temperature Monitoring
LNG storage tanks require continuous level monitoring to manage inventory and prevent overfill. Level measurement uses radar, servo, or differential pressure methods adapted for cryogenic service. Temperature monitoring at multiple elevations within the tank detects stratification conditions that could lead to a rollover event. Rollover is the rapid mixing of stratified LNG layers of different density and temperature, which releases large volumes of boil-off gas rapidly. Wikota Electrical installs tank level and temperature instrumentation in accordance with the tank design specification and API 625 requirements applicable to LNG tanks.
Boil-Off Gas Compression Electrical
Boil-off gas is the natural gas vapor produced by heat ingress into LNG storage tanks. BOG compressors recover this vapor for reliquefaction or use as fuel gas. BOG compressor electrical scope covers compressor motor MCCs, suction and discharge pressure and temperature instrumentation, and the control system managing BOG compressor operation in response to tank pressure. Classified-area wiring applies in the BOG compression area where flammable gas concentrations can occur during normal operation.
Regasification Facility Electrical and I&C
Vaporizer and Send-Out Electrical
Regasification facilities convert LNG back to gas phase for pipeline send-out. Open rack vaporizers use seawater as the heat source, submerged combustion vaporizers use gas-fired burners, and ambient air vaporizers use convective heat transfer. Each vaporizer type has distinct electrical scope for pumps, burners, controls, and instrumentation. Send-out compressor electrical scope, metering instrumentation for pipeline interconnect, and odorization system electrical connections complete the regasification facility scope.
Safety Instrumented Systems at LNG Facilities
LNG facilities require safety instrumented systems that monitor critical process parameters and initiate defined protective actions when those parameters exceed safe limits. SIS scope covers combustible gas detection throughout the facility, emergency shutdown valve actuation and position monitoring, high-level shutdown instrumentation on LNG storage tanks, and the safety PLC managing protective logic. SIS installation follows IEC 61511 requirements for functional safety, and SIS functional testing is performed before the facility is placed in service.
Small-Scale and Peak-Shaving LNG Facilities
Small-scale LNG facilities produce liquefied natural gas for truck loading, marine bunkering, or industrial use at smaller volumes than export-scale terminals. Peak-shaving LNG facilities store liquefied natural gas during periods of low demand and regasify it during high-demand periods to supplement pipeline supply. Both facility types share the same cryogenic electrical and I&C requirements as larger LNG terminals at a scale consistent with the project sizes where Wikota Electrical operates. The electrical scope covers liquefaction or storage electrical systems, BOG compression, metering, and safety instrumented systems required for LNG service at any scale.
| Instrumentation & Controls | Cryogenic instrumentation, tank level and temperature monitoring, SIS field devices, custody transfer metering, fire and gas detection, and commissioning for LNG facilities. |
|---|---|
| Electrical Construction | Refrigeration compressor MCCs and VFDs, medium-voltage distribution, cold box electrical penetrations, classified-area wiring, BOG compression electrical, and regasification facility electrical. |
| Engineering & Design | Construction management, SIS commissioning coordination, custody transfer metering calibration, and project visibility. |
| Project Delivery | Zero recordable incidents, NFPA 70E, IEC 61511 SIS commissioning support, classified-area compliance, and ISNetworld tracking. |
| Safety, Quality & Compliance | Contamination control procedures for high-purity service, oxygen deficiency monitoring, zero recordable incidents, and NFPA 70E compliance. |
Frequently Asked Questions
An LNG liquefaction facility requires electrical and I&C scope for the refrigeration compressor train, cold box instrumentation, storage tank level and temperature monitoring, BOG compression, and the safety instrumented system protecting the facility from overpressure, overfill, and flammable gas accumulation events. A regasification facility requires electrical scope for vaporizers, send-out compressors, and metering and odorization systems at the pipeline interconnect. Both facility types require classified-area wiring throughout areas where LNG vapor can accumulate, cryogenic-rated instrumentation in service below minus 200 degrees Fahrenheit, and safety instrumented systems designed and commissioned to IEC 61511 functional safety requirements.
Rollover occurs when stratified layers of LNG with different densities and temperatures mix rapidly, releasing large volumes of boil-off gas in a short period. The gas release rate during rollover can exceed BOG compression system capacity, causing tank pressure to rise rapidly. Rollover is prevented by monitoring temperature at multiple elevations within the tank to detect stratification before it becomes severe, and by managing LNG filling operations to minimize the introduction of LNG that is significantly different in density or temperature from the tank inventory. Temperature monitoring instrumentation at multiple tank levels, combined with control system alarm logic, is the primary instrumentation defense against rollover.
A safety instrumented system is an independent protection layer that monitors defined process parameters and initiates protective actions when those parameters exceed safe limits. At an LNG facility, a SIS monitors tank level, pressure, and temperature; detects combustible gas accumulations; and responds by closing emergency shutdown valves, activating deluge systems, or initiating safe shutdown sequences. The SIS operates independently of the process control system and is designed to maintain its protective function even when the process control system fails. IEC 61511 is the international standard governing SIS design, installation, and testing for the process industry.
A baseload LNG facility operates continuously, liquefying pipeline gas for export or distribution on an ongoing basis. The electrical scope reflects continuous operation of large refrigeration compressors, storage tanks, and loading or send-out systems. A peak-shaving LNG facility liquefies gas during periods of low demand and holds it in storage until high-demand periods when it is regasified and injected into the pipeline. The liquefaction equipment at a peak-shaving facility may operate only seasonally, which affects how electrical systems are designed for intermittent operation, including motor starting requirements for infrequent compressor starts and heat tracing maintenance during periods when liquefaction equipment is not in service.