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Beirut Explosion - What Happened?

Updated: Mar 15, 2021

Beirut, Picture by AFP / Getty

On the evening of Tuesday, August 4th, 2020, an explosion occurred in Beirut, Lebanon's capital city. This explosion caused a significant number of fatalities, injuries, and substantial damage to the city.

Giving the significant public impact produced by the explosion, people are questioning about what happened and if the tragic event could have been prevented. Although many aspects of the incident remain unknown at the moment, with the information available, it is clear that this event resulted due to a failure of an adequate safety management system implementation.

The Chemical Center for Process Safety (CCPS) has established 20 elements distributed in 4 accident prevention pillars. These elements are defined in the Guideline for Risk-based Process Safety (RBPS). The process safety community considers this guideline as one of the best practices of hazardous materials risk management. Proper implementation of these 20 elements in an organized management system is critical for reaching safety excellence in any organization.

Considering the information available about the Beirut explosion, a high-level review can be performed to understand the causes. Nevertheless, a proper formal investigation should be conducted to understand these causes and implement measures that prevent similar events from occurring. The Tripod Beta incident investigation method is used to organize the information logically and visually. Tripod Beta is an incident investigation approach that is based on the tripod concept. This method defines an accidental event by three main elements: the event that took place, an agent that creates a change, and an object or target that changes or receives the effects from the agent. These elements are shown visually in a tripod diagram as below.

This diagram can be extended by considering that targets or agents can also be an event of a precursory tripod. According to the publicly available information, the Beirut explosion occurred when a fire spread to a significant amount of ammonium nitrate stored in the nearby area. The information indicates that the initial fire started when a welding operation performed in a door ignited fireworks stored in the area.—The following tripod diagram illustrates the accident causation sequence.

In a controlled environment, safety measures are implemented, separating the agent from the target preventing the event from occurring; these safety measures are called barriers. Incidents developed when these barriers fail or are not implemented, allowing the agent to impact the target and causing the event.

Reviewing the CCPS accident prevention pillars allows us to identify and understand the different barriers that failed or were missing.

Commit to Process Safety

This pillar is one of the most important as it generally governs the performance of the others. This pillar establishes a dedication and obligation to safety, creating a leadership commitment toward safety excellence. Without a proper and robust compromise, the organization generally does not improve.

An organization that fully supports safety as a core value do the right thing, in the right way, and nurturing their employees to do the same.

Available information suggests that there was a lack of safety commitment. Ammonium nitrate has been stored for six years in the warehouse since it was confiscated without consideration of proper conditions. It is unknown if the organization discussed the situation at some time. However, the concern was not enough to act and improve the conditions to reduce the risk to acceptable levels.

Another essential element in this pillar is complying with standards. This element identifies, develop, and implement relevant safety standards, codes, regulations, and laws. The National Fire Protection Association (NFPA) has several hazardous material standards that can be applied to ensure safety when handling or storing these materials. Specifically, NFPA 400 Hazardous Materials Code has a complete chapter regarding ammonium nitrate, which includes storage and handling ammonium storage requirements. Some barriers identified in NFPA 400 regarding ammonium nitrate involve:

¨ Prohibition of hot work activities on buildings that store ammonium nitrate,

¨ Separation and segregation of ammonium nitrate from combustible materials using a fire barrier (with at least 2 hrs of fire resistance),

¨ Installation of a fire suppression system (e.g., sprinkler system) to control a potential combustible material ignition.

Additionally, the code requires a permit by the authority having jurisdiction when the facility stores more than 453 kg of ammonium nitrate. This requirement suggests that the inventory should be limited - the Beirut warehouse stored 2,750 metric tons of nitrate ammonium.

Risk Management (Understand Hazards and Risk & Manage Risks)

Businesses that understand their risks can make wiser and more sound decisions allowing continuous operation. This pillar establishes the need to identify the hazards and evaluate their associated risks to plan, develop, and deploy stable and control operations

The CCPS RBPS shows two different pillars for Risk Management, Understand Risks, and Manage Risks. However, these two pillars can be grouped in a single Risk Management pillar that includes the risk evaluation and the implementation of diverse elements to maintain the risk at acceptable levels.

Understanding the risk requires product and material knowledge and context. In the case of ammonium nitrate, it is known that it is highly soluble in water and is not considered flammable or toxic in its natural form. However, ammonium nitrate has a hidden hazard. It is a strong oxidizer, which from a chemical safety perspective, means that it can be explosive when mixed with other combustible materials, or it can be decomposed violently at elevated temperatures producing an explosion.

Although it is unknown at this moment if a risk assessment was performed, every information seems to indicate that a thorough and detailed evaluation was not performed. An adequate risk assessment would have suggested that storing ammonium nitrate without proper conditions can cause an explosion with significant potential consequences.

Predictive process safety consequence models are available to estimate the potential impact of hazardous materials accidents, including explosions.

The process safety industry has quantitative risk analysis (QRA) used in risk evaluation. Using this approach for risk analysis probably should have indicated that storing this material in an area surrounded by a populated area was unacceptable.

Any risk assessment probably would have pointed out that storing ammonium nitrate in a warehouse near fireworks is not recommended. Fireworks are a known combustible material with the potential to ignite, creating a fire, which could expose the ammonium nitrate to high temperatures.

From the operation perspective, this pillar focuses on operation practices and activities that maintain acceptable risk levels and prepare to respond to an eventual incident. At the moment, there is no information about how the storage was managed. However, some preliminary information reported by the media indicates that a welding activity in a door caused the initial fire. This activity is directly related to one of the main elements in this pillar, safe work practices, which include the hot work permit. A proper application of the hot work permit ensures that fire hazards are review and mitigated before starting these activities. The NFPA standard 51B establishes best practices that can be used during hot work permits to prevent ignition during these activities.

Considering the uncontrolled fire that preceded the explosion suggests that safe work practices were not adequately implemented to prevent that a spark ignites combustible material in the vicinity.

The tripod diagram can be updated with the missed or failed barriers identified in NFPA standards and risk management. Note that the risk assessment also reaffirms the barriers defined by NFPA 400.

At the moment, it is not possible to determine if barriers were missing or failed; therefore, these are drawn as failed barriers unless it is clear that it was not implemented, e.g., a proper safe separation between the storage location and the general public.

Learn from Experience

This pillar involves constant monitoring and acting on internal and external information. One crucial element in this pillar is the Incident investigation, which relates to the design and implementation of processes for reporting, tracking, and investigating incidents. However, this requirement should not only apply to internal incidents; it should include any event related to the technology, process, or materials used or handled by the organization.

These external incidents should be investigated to understand the risk and ensure that similar events would not occur in the managed facility. In the Beirut explosion, there were several incidents that occurred due to thermal decomposition of ammonium nitrate, resulting in a significant impact, including the number of fatalities and property destruction. One of the most notable incidents is the 1947 Texas City Disaster that killed 581 persons, injured more than 2,000, and caused millions of dollars in damages. It is essential to notice that the amount of ammonium nitrate in this incident was similar to the amount stored in Beirut. Additionally, other more recent events can be studied like the west fertilizer explosion in West Texas in 2013 or the 2015 blast in Tianjin in China.

Typically, previous incidents are reviewed during risk assessments, allowing them to understand the issues that occurred and identify barriers that prevent similar events from occurring in the assessed installation.

It is inferred that incident research and investigation were not performed in Beirut or considered credible despite the evidence from the past, failing to learn from past events.

Another essential element in this pillar is the Audits, which are used to evaluate the conditions and the proper implementation of the safety management system. A good audit would have identified different safety barrier failures and indicate that a proper correction was needed. It is unknown if the storage implemented an appropriate audit program. Even if these were performed, these issues were not identified, or the recommendations were not implemented, failing the audit objective of ensuring that safety measures are implemented to maintain an acceptable level of risk.

After reviewing the accident prevention pillars, different failures can be added to the tripod diagram. Three main failures are defined:

  • Active failures are the immediate failure of a defined barrier. It is the most visible trigger and includes things as operating procedures or safe work practice deviations.

  • Preconditions are active failure underlying causes and include aspects as poor design or inadequate decisions.

  • Latent failures are management level failures that have implications for a broad group of possible occurrences. Correcting latent failures would prevent recurrence of this and similar circumstances. The root cause is typically found by evaluating the latent cause in detail.

Overall, reviewing the available information, suggest that failures that led to the Beirut explosion include:

  • Risk Management failure, which includes lack of risk understanding and failure to learn from past experiences

  • Safety Commitment failure

  • Failure to comply with standards

All these failures can be tied to a lack of safety culture. However, the specific failure modes need to be identified in a detailed investigation, including interviews and evaluation of the implemented management system and decision-making process.◆


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