Liquefied Natural Gas (LNG) facilities are high-risk industrial sites that demand the highest levels of safety and reliability, especially in electrical system design. These sites handle large volumes of flammable gases and vapours in extreme environmental conditions, from offshore platforms to coastal terminals. In such hazardous environments, explosion-proof enclosures are vital for ensuring operational integrity and personnel safety.
Why LNG Facilities Are Classified as Hazardous Areas
LNG facilities process and store methane-rich gas under cryogenic conditions. When leaked or vaporized, LNG quickly forms explosive atmospheres. Because of this, different areas of the plant are classified into zones based on the likelihood of a flammable atmosphere being present.
- Zone 1 refers to areas where an explosive atmosphere is likely to occur during normal operations.
- Zone 2 covers areas where the explosive atmosphere is not likely to occur in normal operation, and if it does, will exist for a short time.
Learn more about zone classification in hazardous area.
Electrical installations in these zones must meet stringent safety requirements, with explosion-proof enclosures serving as the primary defence against ignition sources. Without proper containment, even a single spark from a relay or terminal can cause devastating chain reactions. Learn more about hazardous zone classification.
The Function of Explosion-Proof Enclosures
Explosion-proof enclosures, also known as Ex d or flameproof enclosures, are designed to do two things: contain any internal explosion caused by electrical faults or arcs and prevent flame or heat from escaping and igniting the surrounding atmosphere.
These enclosures are commonly used to house:
- Terminal blocks
- Instrumentation (such as pressure and temperature transmitters)
- Local control panels and HMI interfaces
- Switches, relays, and PLC components
In LNG plants, these components are often located close to gas processing units, vapour handling equipment, or tank farms, areas where reliable explosion protection is non-negotiable.
Harsh Environment Considerations in LNG Sites
Unlike standard industrial environments, LNG facilities present a unique set of environmental challenges that explosion-proof enclosures must withstand over long operational lifespans.
1. Corrosive and Humid Atmospheres
LNG terminals are typically located near the ocean, exposing equipment to salt spray and humidity. Enclosures must be constructed from corrosion-resistant materials like SS316 stainless steel or coated aluminium. Without this protection, corrosion can compromise sealing integrity and structural strength.
2. Cryogenic Temperatures and Thermal Cycling
LNG handling involves extremely low temperatures. Rapid changes in ambient temperature can lead to thermal stress and condensation, which affect gaskets, seals, and internal components. Explosion-proof enclosures used in these zones must be capable of withstanding thermal cycling without degrading the flamepath or compromising ingress protection.
3. Vibration and Mechanical Impact
Rotating equipment, compressors, and marine loading arms create significant vibration. Mechanical shocks are also common during installation or maintenance. Enclosures must meet relevant impact resistance (IK rating) and vibration resistance standards to ensure they continue to perform under such conditions.
Standards and Certifications for Hazardous Area Enclosures
Explosion-proof enclosures used in LNG plants must comply with internationally recognised certifications. These ensure the enclosures are not only explosion-proof but also suitable for long-term deployment in harsh, hazardous environments.
Common certifications include:
- IECEx and ATEX for global applications (especially Australia and Europe)
Key standards that apply to LNG facilities:
- IEC 60079-0: General requirements for electrical apparatus in explosive atmospheres (Ex)
- IEC 60079-1: Contains specific requirements for the construction and testing of electrical equipment with the type of protection flameproof enclosures ‘d’ (Ex d)
- IEC 60529: Ingress protection (IP66/IP67) for dust and water resistance for enclosures
- ISO 9227: Salt spray testing for corrosion resistance
Certification testing includes simulated internal explosions, hydrostatic pressure testing, ingress protection (IP) testing, flamepath validation, and corrosion chamber endurance.
Common Applications in LNG Facilities
Explosion-proof enclosures are integrated into multiple parts of an LNG operation. Some of the most common applications include:
Storage Tank Farms
These areas require continuous monitoring of pressure, level, and temperature. Explosion-proof junction boxes and transmitter housings are often installed directly on tank skids or pipelines, requiring both hazardous area and weatherproof protection.
Marine Jetties and Loading Arms
Exposed to salt spray and dynamic movement, these zones use flameproof control stations with anti-condensation heaters, marine-grade coatings, and vibration-resistant mounts.
Compressor Stations and Turbine Rooms
These areas present both mechanical and thermal hazards. Modular enclosures with heavy-duty latches, removable wiring trays, and high ambient temperature ratings are commonly used.
Best Practices for Installation and Maintenance
To ensure reliability and compliance, explosion-proof enclosures must be installed and maintained according to strict procedures. This includes:
- Using certified cable glands: All entry points must be sealed with glands that match the Ex d rating and are appropriately sized and approved.
- Avoiding unauthorised modifications: Field modifications such as drilling or cutting are prohibited, as they can compromise the flamepath and invalidate the certification.
- Following IEC 60079-14 and -17: These standards outline installation and inspection requirements, respectively. Regular inspections should check for seal degradation, corrosion, and physical damage.
Evolving Trends in Hazardous Area Enclosures
Explosion-proof enclosure technology is advancing to meet the growing demand for digitisation and remote monitoring. Modern Ex d enclosures are now being designed to support:
- Smart diagnostics: Internal temperature and humidity sensors that detect early failure signs
- Fibre optic and fieldbus compatibility: For integration into distributed control systems (DCS)
- Modular internal layouts: For easier servicing, reducing downtime in high-risk areas
Some manufacturers are also exploring the use of lightweight composites that offer similar mechanical and flameproof performance with reduced weight, ideal for offshore or elevated installations.
Explosion-proof enclosures are essential for maintaining electrical safety and operational reliability in LNG facilities. From storage tanks to jetties and compressor buildings, these rugged enclosures provide the last line of defence against the risks of ignition in explosive gas atmospheres.
When designed and applied correctly, they enable LNG facilities to operate safely in some of the most challenging environments on the planet. Selecting the right enclosure material, understanding certification requirements, and adhering to best installation practices are all critical steps in ensuring long-term success and regulatory compliance.
Need help selecting enclosures for LNG applications?
Contact Transtech today and our engineering team can assist with product selection, compliance advice, and system integration, tailored for Zone 1 and Zone 2 hazardous areas in oil and gas operations.