Investigating Process Safety Incidents

The final incident investigation report written by the assigned incident investigation team (which may include members from the client) can be written in a less structured way depending on the extent of the incident. A detailed discussion of how and why to conduct incident investigations can be found in the AIChE publication. Guidelines for Investigating Process Safety Incidents, Second Edition. 

This chapter provides an overview of a management system for investigating process safety incidents. It opens with a review of management responsibilities and presents the important features that a management system must address to be effective. It examines systematic approaches that help implement incident investigation teams, root cause determinations, recommendations, follow-up, and documentation. 

The investigation committee method is another unsuccessful approach. This unstructured approach is historically significant and was judged inadequate for investigating process safety incidents because it produced incomplete and inconsistent results. It often did not find the root cause level or all the root causes. 

Are there written procedures or protocols for reporting and investigating process safety incidents ... 

The terms root cause or multiple root causes appear several times without a clear definition. When Jack Philley teaches the Investigating Process Safety Incidents course for the AIChE, he offers several clear definitions. He describes a root cause as a prime reason, underlying cause, and most often associated with breakdowns or flaws in the management systems. Furthermore, Philley s class notes point out definitions from the Department of Energy Guidelines in his handout, which states ... 

Also note the following temperatures of interest to process safety incident investigation teams (Perry and (ireen, 1997 NFPA 422M NFPA 1997 and Avallone and Baumeister, 1996). 

Like the previous edition, the book remains focused primarily on investigating process-related incidents that present realized or potential catastrophic consequences (that is, accidents as well as near misses). However, readers will find that the methodologies, tools, and techniques described in the following chapters may also be applied when investigating other types of occurrences such as reliability, quality, and occupational health and safety incidents. 

Many major process safety incidents were preceded by precursor occurrences. These occurrences were unrecognized or ignored because nothing bad actually happened. The lessons learned from such occurrences, typically referred to as near misses, can be extremely valuable in averting disaster. However, this benefit is only realized when they are recognized, reported, and investigation techniques are properly applied. This chapter describes near misses, discusses their importance, and presents the latest methods for helping ensure appropriate near misses are reported. 

This chapter addresses methods and tools used successfully to identify multiple root causes. Process safety incidents are usually the result of more than one root cause. This chapter provides a structured approach for determining root causes. It details some powerful, widely used tools and techniques available to incident investigation teams including timelines, logic trees, predefined trees, checklists, and fact/hypothesis. Examples are included to demonstrate how they apply to the types of incidents readers are likely to encounter. 

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. 

This group must be familiar with the concepts, policies, extent of commitment from upper-level management, and specific assignments of responsibility associated with process safety incident investigation. 

Analysis, that can assist with the identihcation of causal factors. The concepts of incident causation encompassed in these tools are fundamental to the majority of investigation methodologies. (See Chapter 3 for information about the Domino Theory, System Theory, and HBT Theory.) The simplest approach involves reviewing each unplanned, unintended, or adverse item (negative event or undesirable condition) on the timeline and asking, Would the incident have been prevented or mitigated if the item had not existed If the answer is yes, then the item is a causal factor. Generally, process safety incidents involve multiple causal factors. 

Leading a Process Safety Incident Investigation Team... 

The team leader is responsible to plan and direct the team activities. The specific plan for the team should include a designated mechanism for documenting the team activities, deliberations, decisions, commimications, and a record of documents requested, received, or issued. The primary objectives of a process safety incident investigation plan are to ... 

Temperatures of Interest to Process Safety Incident Investigation Teams... 

Johnson s interpretation of MES concepts is known as Events Causal Factor Charting (E CF), or Causal Factor Charting for short, and has been adopted as one of the building blocks of several methodologies for process safety incident investigation. 

Events Causal Eactor Charting (E CE) (5) was adopted by the developers of MORT to identify and document the sequence of events leading to an incident. A number of proprietary process safety incident investigation methodologies, such as SOURCE ) and TapRooT C) include E CF as one of their building blocks. 

The first phase of process safety incident investigation involves gathering all the pertinent facts from the collected evidence, whether derived from interviews, site and equipment inspections, or document reviews. At this... 

This approach is not recommended for process safety incident investigation. If the team conducting the incident investigation has been chosen for their experience, technical knowledge, and skills, they are best placed to develop the recommendations to prevent a recurrence. 

Root (or primary) causes, immediate (or secondary) causes, and contributory factors are identified, analyzed, and discussed in this section of the report. As described in Chapter 9, process safety incidents are the result of many factors, and therefore singling out one cause is rarely the proper approach. Some experts indicate that if a fault tree or causal factor chart was developed as part of the investigation it should be incorporated to facilitate understanding. 

In practice, external sharing of lessons learned from investigations is not an easy task. Those who wish to share details of serious incidents with the public encounter numerous challenges. Many process safety incidents involve fatalities or third party activity, and thus may ultimately end up in litigation. 

As previously stated, the American Chemistry Council also recognizes this concept as an integral part of the code of Responsible Care , Process Safety Code of Management Practices, Companies should openly share nonproprietary results from internal process safety incident investigations and related research through the auspices of trade and professional associations, and other networking opportunities. Other organizations should strive to benefit from the lessons learned by others and keep abreast of latest developments and safety alerts. 

For decades, most chemical manufacturers have employed a hierarchy of reviews, investigations, and reports for safety and environmental insults and incidents, ft is obvious that a Process Safety Incident Investigation is the highest level investigation that can incorporate other more limited investigations and reports. 

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