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Process safety programs require many decisions on their design and implementation. These decisions directly impact the risks posed by processes. Unfortunately, decisions can be unreliable when they are influenced by cognitive biases, which are influences on human judgment and decision making that can cause reasoning errors and produce irrational decisions. Many different cognitive biases have been identified and they occur commonly. They are difficult to detect and override because they are used unconsciously and automatically.

The identification of hazard scenarios in process hazard analysis (PHA) is subject to the effects of cognitive bias by PHA team members, which may lead to the omission of scenarios from PHA studies.

A recent incident at a Royal Dutch Shell petrochemical plant in Moerdijk, the Netherlands, on June 3, 2014 likely provides an example. The incident involved an explosion and fire that injured two contract workers and caused extensive process damage. The investigation concluded that the incident resulted from unexpected exothermic reactions. A Reactive Hazard Assessment (RHA) had been conducted but the analysts did not identify the reaction that caused the explosion. The RHA relied on the general belief that such a reaction could not occur although this assumption had not been verified empirically. Subsequently, laboratory tests determined that two exothermic reactions had occurred.

Fundamentally, the incident can be attributed to the decision made during the RHA regarding the lack of a reactive hazard. A key question is why the assumption of lack of reactivity was accepted. Based on the description of the RHA study, it is likely that one or more cognitive biases played a role. Hazard analysis studies are subject to various types of cognitive bias. Groupthink is a phenomenon in which a group of people share common but possibly false beliefs and think and make decisions in the same way. Mindsets are assumptions held by an individual which are so established that the individual does not recognize they exist and continues to accept prior choices as valid. Deference to authority occurs when people accept the opinions of perceived authorities without substantiation of the views expressed. Group polarization is the tendency for a group of people to make decisions that are more extreme than the initial inclinations of its members. Such cognitive biases would help to explain the decision made during the RHA regarding the lack of a reactive hazard. The telltale indicator that reveals cognitive bias is use of the words “generally believed” in the description of the incident when referring to the lack of reactivity. Belief is not knowing. Qualification by “generally” implies broad agreement with the belief, although unproven.

Cognitive biases can affect all decisions made by people. Clearly, process safety decisions are particularly important and significant effort to address the impact of cognitive biases is warranted. Process safety practitioners must strive to recognize when reliance is being placed on opinions and assumptions which may be tainted by cognitive biases. As much tangible data and information as possible should be used to avoid the need to rely on opinions. The use of a devil’s advocate who challenges and debates views offered by others in order to help determine their validity can help to address cognitive biases.

Process safety requires practitioners to make many decisions, all of which can be influenced by cognitive biases. Key decisions can benefit from the application of the discipline of critical thinking which can help to identify flaws in reasoning and help to prevent process safety incidents. Are your decisions sound and free from bias?

Further information can be found in these articles:

Learning from Incidents - Awareness Alert. Explosions in SMPO Hydrogenation Unit, http://www.arbeidshygiene.nl/-uploads/files/insite/cgc-20160121-explosions-in-smpo-hydrogenation-unit.pdf.

Process safety incidents, cognitive biases, and critical thinking, Hydrocarbon Processing, November, 2017.

Cognitive biases in process hazard analysis, Journal of Loss Prevention in the Process Industries, Volume 43, pages 372-377, September, 2016.

The role of people and human factors in performing process hazard analysis, J. of Loss Prevention in the Process Industries, Vol. 26, pages 1352-1365, 2013.

A framework for critical thinking in process safety management, Process Safety Progress, Volume 35, Issue 4, pages 337–340, December 2016.