How can you identify potential hazards in a Layer of Protection Analysis?

1 Identify the initiating events

An initiating event is a deviation from the normal operating conditions that can trigger a hazardous scenario. For example, a loss of cooling water, a power failure, or a human error. You can identify the initiating events by using different techniques, such as hazard and operability study (HAZOP), failure modes and effects analysis (FMEA), or fault tree analysis (FTA). These techniques can help you examine the possible causes and consequences of each deviation.

2 Identify the consequences

The consequences are the undesirable outcomes that can result from the initiating events. For example, a fire, an explosion, a toxic release, or an environmental damage. You can identify the consequences by using different techniques, such as dispersion modeling, fire modeling, explosion modeling, or consequence analysis. These techniques can help you estimate the severity and the impact of each outcome.

3 Identify the independent protection layers

An independent protection layer (IPL) is a device, system, or action that can prevent or mitigate the consequences of the initiating events. For example, a pressure relief valve, a fire detection system, or an emergency shutdown procedure. You can identify the IPLs by using different techniques, such as safety integrity level (SIL) analysis, reliability analysis, or human reliability analysis. These techniques can help you evaluate the performance and the availability of each IPL.

4 Identify the enabling conditions

An enabling condition is a factor that can increase the likelihood or the severity of the initiating events or the consequences. For example, a maintenance activity, a weather condition, or a process change. You can identify the enabling conditions by using different techniques, such as risk matrix, bow-tie diagram, or event tree analysis. These techniques can help you assess the frequency and the influence of each factor.

5 Identify the risk criteria

The risk criteria are the standards or guidelines that can help you decide whether the risk of a hazardous scenario is acceptable or not. For example, a maximum tolerable frequency, a maximum tolerable consequence, or a risk ranking. You can identify the risk criteria by using different sources, such as regulations, industry standards, best practices, or stakeholder expectations. These sources can help you define the acceptable level of risk for each scenario.

6 Perform the LOPA

After you have identified the potential hazards, you can perform the LOPA by using a worksheet or a software tool. The LOPA will help you calculate the risk of each hazardous scenario by combining the frequency of the initiating events, the probability of failure of the IPLs, and the influence of the enabling conditions. The LOPA will also help you compare the risk with the risk criteria and determine whether you need to add or modify any IPLs to reduce the risk to an acceptable level.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?