Hazard Analysis and Risk Assessment in LNG Operations

Every liquified natural gas (LNG) facility must understand, quantify, and mitigate its unique risks. Process Hazard Analyses (PHAs), Consequence Modeling, and Quantitative Risk Assessments (QRAs) are essential tools. They guide decision-making from facility layout to daily operations.

In this post on maritime and LNG safety, Steve Calabrese, who manages Maritime Services, is joined by several colleagues. They include Colin Armstrong, Richard MacNguyen, and Camille Levine from Quantitative Risk Services, and Brad Fuller, Manager of US Operations. Together, they explain how these approaches work in practice and why they are essential for LNG safety.

Process Hazard Analysis Hazard Scenarios Specific to LNG Operations

Q: What are the most critical hazard scenarios you consider in a PHA?

A: When conducting a PHA for an LNG operation, the team focuses on the most critical hazard scenarios, those involving credible loss of containment events. These scenarios could have significant impacts on employee safety, the public, and business continuity. At the top of the list are loss of containment events during LNG production, process transfer, storage, or transit. By prioritizing these hazards, PHAs help ensure that safeguards are in place to protect people, assets, and operations. At the top of the list are loss of containment during LNG production, process transfer or storage, as well as during transit. These could result from a major piping or manifold failure at a facility, or a transportation accident, resulting in a cryogenic release. These types of scenarios can result in rapid pool formation, flammable vapor cloud dispersion, with the potential for ignition. Making them one of the highest-consequence events considered.

Another critical potential loss of containment scenario is overpressure and failure of process equipment or transportation vessels. These can range from blocked piping and thermal expansion, gas blowby, boil off gas (BOG) generation, and rapid phase transitions with the potential for violent vaporization.

We also focus on additional ignition-related scenarios, including jet fires from pressurized leaks and pool fires from spills over ground or water. These thermal hazards drive requirements for equipment spacing, passive fire protection, and firefighting system design.

As flammable releases can escalate quickly, the PHA team must ensure that sufficient safeguards are built into the design. These safeguards may include inherent safety measures, process controls, safety instrumented systems, and pressure relief, as appropriate. Each barrier must also be monitored and maintained throughout the operation’s life cycle to remain effective. By employing risk-based approaches, projects and operations can develop protection measures that are both cost-effective and prudent. This approach supports the safe management of identified hazards over the long term.

Finally, human and operational factors are built into the PHA process. Scenarios such as simultaneous operations (SIMOPS), operations/ maintenance errors, and failures in communication during vessel loading/ unloading are reviewed. Often these scenarios highlight the need for more robust procedures, additional training, and additional activity-based layers of protection.

The PHA provides a structured framework to identify the full range of scenarios that could cause deviations from normal operations and assesses their potential impacts. It forms the foundation for implementing or recommending safeguards to manage risk. It also helps determine whether additional emergency response measures are needed. Beyond risk management, the PHA also ensures compliance with safety standards, including 33 CFR Part 127, National Fire Protection Association (NFPA) 59A, and Pipeline and Hazardous Materials Safety Administration (PHMSA) requirements. By systematically addressing hazards, PHAs play a critical role in keeping LNG operations safe and resilient.

The Influence of a Quantitative Risk Assessment

Q: How do quantitative risk assessments (QRAs) influence facility layout and operational decision-making?

Quantitative techniques, including consequence modeling and risk analysis, are critical tools for shaping the siting, layout and operations of LNG facilities. A QRA expands standard code compliance and qualitative and semi-quantitative PHA approaches to provide a data-driven decision making.

For example, modeling of flammable vapor dispersion, thermal radiation, and vapor could explosion directly influence facility siting and layout. Results are used to mitigate offsite impacts by establishing exclusion zones around storage tanks, loading systems, transfer manifolds, and other process equipment, as well transiting vessel. Additionally, consequence modeling helps ensure that control rooms, administrative buildings, other occupied buildings, and muster points are located outside hazardous impact zones. It can also provide the basis for safe building design. Detailed consequence modeling tools, such as Computational Fluid Dynamics (CFD), are often used to more accurately determine the potential hazards and impacts.

On the operational side, QRA findings guide decisions on SIMOPs, transfer scheduling, and the allocation of emergency response resources. They provide insight into how risks can be managed effectively during day-to-day operations. QRA results also help determine whether existing risk reduction measures are sufficient or if additional safeguards are needed. This ensures that risks remain within acceptable company or regulatory criteria. These measures may include additional layers of protection, enhanced leak detection, or changes to mooring and vessel traffic controls.

Ultimately, the QRA provides a quantifiable link between hazard identification and real-world decision-making. It supports compliance with regulatory requirements under the Federal Energy Regulatory Commission (FERC), the U.S. Coast Guard (USCG), and NFPA 59A. It also gives operators confidence that the facility is designed and managed with a clear understanding of both the likelihood and potential consequences of LNG incidents.

Beyond PHAs and QRAs: Additional Studies That Strengthen LNG Safety

Q: What other process safety studies are critical for LNG operations, and how do they support risk management?

In addition to PHAs and QRAs, several other process safety related studies are critical for LNG operations, particularly those required by FERC under Resource Report 13. Per these FERC requirements, Road and Air Safety and Reliability Impact studies must be performed to assess impacts and risks to an LNG facility posed by road vehicles and aircraft during construction and operation phases. Since road and air safety studies focus on external hazards, they provide an additional evaluation of safety and  risks that may not be fully addressed in PHAs or QRAs.

The road study analyzes site traffic and assesses collision risk between vehicles and equipment. The risk-based methodology used for the road study evaluates the likelihood and severity of potential traffic accident scenarios. This allows for high risk scenarios to be identified and risk reduction measures to be recommended as needed. Likewise, the air safety study analyzes aircraft traffic from nearby airports and assesses risk of aircraft collisions with the facility equipment. These safety studies consider visibility, day/night conditions, passing vehicle direction, passing vehicle contents, vehicle/ aircraft  sizes, flight paths, and speeds.

The FERC also specifies requirements for crane and lifting, rail cars, and waterway safety and impact studies. These studies serve a similar purpose to road and air safety studies and follow similar methods. The studies should be conducted as well as relevant to the facility to ensure comprehensive risk management and regulatory compliance.

Closing Thoughts

Effective hazard and risk analysis turns complexity into clarity. With decades of experience applying PHAs and QRAs for LNG projects and operating facilities worldwide, AcuTech helps companies make sound risk-based decisions. Our expertise supports the ongoing safety and reliability of LNG operations.

For those attending the Americas LNG Summit in Lake Charles this October, Steve will be available at our booth. He will answer questions and share more insights with attendees.