Root causes of incidents

In addition to the proactive uses of the SRK model described in the two previous sections, it can also be employed retrospectively as a means of identifying the underlying causes of incidents attributed to human error. This is a particularly useful application, since causal analyses can be used to identify recurrent vmderlying problems which may be responsible for errors which at a surface level are very different. It has already been indicated in Section 2.4.1 that the same observable error can arise from a variety of alternative causes. In this section it will be shown how several of the concepts discussed up to this point can be combined to provide a powerful analytical framework that can be used to identify the root causes of incidents. 

Thorough and effective analyses of workplace incidents are critical components of a comprehensive safety management system. Yet, many incident analysis processes (i.e., accident investigations) fall short. They frequently fail to identify and resolve the real root causes of injuries, process incidents and near misses. Because the true root causes of incidents are within the system, the system must change to prevent the incident from happening again. 

You can use the four RAMP concepts in analyzing what went wrong for any incident. This is one way to think about the incident that can easily reveal mistakes. Often, however, there is more than one mistake that leads to an incident. Additionally, as you think about incidents you will learn that there are underlying or root causes of incidents. In this section we will introduce another method of incident analysis that can reveal more about causes of incidents and how to prevent them. 

Quantified Risk Assessment is valuable at all stages in the life of a plant All plants contain residual risk. Action to evaluate and reduce risk should continue throughout the life of a plant by seddng to eliminate the root cause of incidents particularly with re )ect to maintenance, external threats, procedures, information, information transfer and information processing, the abilities of personnel in the task, and the capabilities d management and organisation. 

The root cause, of incidents, refers to a variety of problem-solving methods that attempt to identify and correct a problem s root causes. It assumes that the best way to solve problems is by eliminating their root causes. It also works tmder the belief that addressing obvious symptoms, sometimes referred to as causal or contributing factors, only serves as a short-term solution and does not prevent the problan from happening again. 

Incident Investigation Previous incidents related to the chemicals or equipment involved in the new toll should be considered during the PHA and must be considered if subject to PSM/RMP compliance. In addition, procedures should be in place to describe how the client will be informed and involved in the investigation. It is veiy important to ensure that action plans addressing the root cause of past incidents were implemented. 

A specific example of a causal model is the root cause tree described in Section 6.8.4 and Figure 6.8. This is a very elaborate model which includes several levels of detail for both equipment and human causes of incidents. The root causes tree is a generic causal model, and may require tailoring for application to specific plants and processes (e.g., in the offshore sector) where other error causes may need to be considered. 

The method is well-structured and provides clear, standardized procedures on how to conduct an investigation and represent the incident process. Also it is relatively easy to learn and does not require the analyst to have a detailed knowledge of the system under investigation. However, the method alone does not aid the analyst in identifying root causes of the incident, but rather emphasizes the identification of the propagation of event sequences. This is an important aspect of developing a preventive strategy. 

The case study has documented the investigation and root cause analysis process applied to the hydrocarbon explosion that initiated the Piper Alpha incident. The case study serves to illustrate the use of the STEP technique, which provides a clear graphical representation of the agents and events involved in the incident process. The case study also demonstrates the identification of the critical events in the sequence which significantly influenced the outcome of the incident. Finally the root causes of these critical events were determined. This allows the analyst to evaluate why they occurred and indicated areas to be addressed in developing effechve error reduchon strategies. 

This case study illustrates how the methodologies described in Chapter 6 can be used to analyze plant incidents and identify the root causes of the problems. Based on this information, specific error reduction strategies can be developed to prevent similar incidents from occurring in the future. Also, the findings of such an analysis can provide the basis for more general discussions about the prevalence of similar error inducing conditions in other plant areas. 

The events and causal factors chart for this incident is shown in Figure 7.9. The primary sequence of events is shown horizontally in bold boxes. Secondary events are shown in the other boxes, and conditions are in ovals. From the diagram three causal factors were identified and carried forward to the Root Cause Coding to establish the root causes of the causal factors. 

On October 30, 1998, a flammable gas release led to gas migration to a non-electrically classified Electrical and Instrumentation (E l) Room. The flammable gas was ingested into the exterior heating and ventilation inlet duct. When the 480 volt primary power switch, within the E l room was remotely shut off, an explosion resulted. The E l module explosion led to a subsequent fire in adjacent production buildings. There were no injuries to personnel. The root cause of the incident was determined to be the failure of management systems... 

The root cause of the incident was determined to be the failure of management systems to adequately understand and address the hazards. 

One approach is to mesh all investigation and root cause analysis activities under one management system for investigation. Such a system must address all four business drivers (1) process and personnel safety, (2) environmental responsibility, (3) quality, and (4) profitability. This approach works well since techniques used for data collection, causal factor analysis, and root cause analysis can be the same regardless of the type of incident. Many companies realize that root causes of a quality or reliability incident may become the root cause of a safety or process safety incident in the future and vice versa. 

In this example, there are two detection systems and two reaction opportunities. These yield three paths that lead to no adverse consequences and four paths that lead to failure with overflow as the consequence. The point is that sometimes there are more opportunities for things to go wrong than to go right. When a system or process fails, it may he difficult to trace the reasons for its failure. Based on available historic incident data, the anatomy of a major incident is rarely simple and rarely results from a single root cause. Serious incidents typically involve a complex sequence of occurrences and conditions. This sequence can include ... 

Methodology—The use of a combination of two or more incident investigation tools to analyze the evidence and determine the root causes of the incident. 

Timelines alone do not identify the root causes of an incident. They should be used in conjunction with other tools, described in the following sections. 

The company will learn that reporting and investigating near misses will enhance overall business performance, particularly because the near misses of a safety incident or environmental release have the same root causes as incidents that detract from quality and productivity. Safety personnel can assist in defining an appropriate near-miss reporting culture. All managers intuitively understand the return on investment from preventing incidents. The effort pays for itself directly through improvements in productivity. 

This chapter addresses typical data gathering needs of major investigations. A team may need to augment the activities in this chapter for the unique circumstances of the incident. Performing the activities oudined in this chapter plus special activities provides the incident investigation team with the data needed to complete the next step—systematic determination of the multiple root causes of the incident. However, data gathering and analysis typically involve much iteration as shown in Figure 8-1. 

The incident investigation team s complete report is attached in the Appendix D and details of the root causes are discussed. The root causes of the incident relate to several process safety management areas ... 

It addresses a root cause of the incident (that is, it fixes the problem). 

The best way to avoid claims and litigation is to prevent an incident from occurring in the first place by having adequate systems and preventive measures in place. The goal of the incident investigation is to learn the root causes of an incident in order to improve management systems, and... 

The root causes of the incident relate to several process safety management areas ... 

Investigation into the Root Causes of Repeated Incinerator Incidents, Donald K. Lorenzo... 

The balance of participants time is spent studying the Dowville case and preparing team reports to be delivered at the end of the workshop. In the reports, the team identifies the root causes of the Dowville incident, identifies deficiencies in Dowville s S/LP/S programs that allowed the root causes to exist, and recommend actions to correct those deficiencies. The team presentations are judged by a panel of managers with one report selected as the winner. 

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