Consequence analysis: 10 things to consider before performing your study

Consequence analysis is a critical aspect of process safety and risk management as it assesses the potential outcomes of the accidental release of hazardous chemicals in industrial processes, ensuring the safety of personnel, assets, and the environment.  

This study aids in regulatory compliance by identifying risks and helps organisations make informed decisions about risk reduction and emergency planning, thus, minimising operational disruptions and ensuring the optimal allocation of resources when implementing safety measures or performing a facility siting assessment. 

Before embarking on your consequence analysis study, here are 10 crucial considerations to ensure a successful analysis.

Objective definition 

Clearly outline the goals and objectives of your consequence analysis. The objectives of a consequence analysis study typically include assessing the potential consequences of accidental chemical releases within a facility.

This is required to evaluate whether a fire, explosion or toxic cloud can take place and the impact that these phenomena have on personnel safety, environmental protection, and property damage.  

Defining the objectives of a consequence analysis is crucial and should clarify (among others) the types of processes that take place in the facility of study, which installations, operational units or equipment will be evaluated and how the facility should be divided into smaller units. 

Data collection 

Gather accurate and comprehensive data related to your facility and processes. This includes information on the facility layout, equipment, chemicals used, process conditions, operating procedures, safety measures, emergency response plans, and historical incident data.  

Additionally, meteorological conditions and terrain information are crucial for assessing potential consequences accurately.  

Gathering comprehensive, accurate and reliable data is essential to ensure the analysis provides a thorough understanding of the risks and potential outcomes of accidents or incidents within the facility.

Hazard identification 

Identifying all relevant hazards is crucial as it lays the foundation for understanding and assessing potential consequences and risks within a facility.  

Hazard identification helps in identifying all possible scenarios and hazards that may lead to accidents occurring, by selecting realistic accident scenarios based on your facility’s operations. The level of complexity depends on the selected method.

Various methods can be employed to facilitate the hazard identification and scenario development. There are simpler ones such as What-If or Checklist process hazard analysis methodologies or more comprehensive ones such as HAZOP, ETA or FMEA. The analysis needs to be performed by an experienced professional. 

Without this initial step, the consequence analysis study may overlook critical risks, and the assessment of potential consequences would be incomplete. 

Model selection 

Choose a model for consequence analysis based on your specific scenario and objectives. Consider factors such as the type of hazard, release mechanism, available data, and required level of detail.

Models may apply different physical laws based on specific substances and process conditions. It is important to choose a model that aligns with the scenario’s aim, as different systems may require distinct governing equations. Understanding the unique characteristics of the model ensures accurate representation and relevance.

Choose models that are validated and verified for your specific conditions and substances being analysed. Validation involves comparing model predictions with experimental data. 

The figure below shows how the dispersion model in Gexcon’s integral modelling software EFFECTS performs against experimental data.

Figure 1. A validation of the dispersion model in EFFECTS against experimental data for lifting hydrogen plumes. 

Level of detail

The level of detail chosen will be influenced by several factors such as the complexity of the facility, the goals of the analysis, available resources, the stage of the project, etc. However, you can actively shape the level of detail by selecting appropriate methods for hazard identification and the type of calculation tool. 

As an example, an approach using a higher level of detail becomes important to consider in studies where geometry is a key factor. For instance, it is relevant when analysing the extent and severity of a potential hazard in a highly congested area, or facilities situated in a location with varied elevations. 

On the other hand, following an approach with a lower level of detail provides a more general overview, which is appropriate in situations where geometry is not as crucial. This is often the case in initial assessments, where the findings are used to identify priorities for further analysis and risk mitigation strategies. 

Tool selection 

To enhance efficiency and ensure accuracy in your consequence analysis, consider opting for a dependable modelling tool or software that aligns with the scope of your study. Each tool will provide you with a diverse set of models and levels of complexity.

Based on the scope of your study, you may choose between CFD software (which stands for Computational Fluid Dynamics) that accounts for flow interaction with complex geometries or integral modelling software tools that save the calculation time while remaining accurate and reliable.

Tools like FLACS CFD modelling software or EFFECTS integral modelling software are excellent choices, as they can streamline the process and provide reliable calculations tailored to your specific needs. 

Regulatory compliance 

Ensuring that a consequence analysis study complies with relevant regulations and standards is essential for several reasons.  

First, it helps maintain legal and regulatory compliance, avoiding potential fines and legal consequences.  

Second, it ensures that safety measures are in line with industry best practices, reducing the risk of accidents and their associated consequences and costs. 

Additionally, compliance demonstrates a commitment to safety and responsible operations, enhancing an organisation’s reputation and stakeholder trust. 

Sensitivity analysis

Assess the sensitivity of results to input parameters and assumptions. This process helps identify which factors have the most significant impact on the outcomes and whether variations in assumptions or data can lead to different results.  

Moreover, sensitivity analysis provides a level of confidence in the study’s conclusions and highlights areas where additional data or refinement of assumptions may be necessary to improve the accuracy of risk assessments and decision-making processes. 

Quality Assurance (QA) 

Quality Assurance (QA) plays an important role in consequence modelling studies, ensuring the reliability and accuracy of the results.  

QA encompasses an extensive review of various elements, such as input parameters, underlying assumptions, and the final results. It involves a thorough cross-checking of the simulation processes to identify and rectify any potential errors or inconsistencies. 

In practical terms, QA involves actions such as a senior consultant examining the elements in their modelling study before presenting them to clients, or a senior safety engineer conducting a thorough review of the calculations before using them as a foundation for determining additional safety measures. 

The implementation of QA in consequence modelling studies ensures that the insights provided are not only reliable but also practical and valuable for real-world decision-making.

Reporting and communication 

Effectively communicate your methodology, assumptions, results, conclusions, and recommendations to stakeholders with clear and concise reports. Consequence modelling tools streamline reporting through the automated generation of graphs, animations, and full reports. 

Various audiences have distinct preferences when it comes to presenting results, including graphs, tables, or alternative visual formats. Consider utilising tools to aid result visualisation such as Google Earth to enhance understanding, especially for non-technical professionals, by providing clear and accessible representations of consequences.

Modelling software such as EFFECTS allows you to visualise how a fire, explosion or toxic cloud could potentially affect surrounding geometries using a representation in an external GIS system such as Google Earth. FLACS, on the other hand, has a very powerful postprocessor tool that presents 3D results and how these phenomena interact with 3D surrounding geometries. 

By considering these key factors, you can conduct a comprehensive and effective consequence analysis study. This study not only enhances safety and risk management in your operations but also ensures that you have a solid foundation for making informed decisions and safeguarding personnel, assets, and the surrounding environment. 

Whether you are assessing potential hazards, designing a new facility, optimising safety measures, or adding new equipment, a well-executed consequence analysis is one of the keys to ensuring safety.

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