Preventing Process Safety Incidents

The ultimate goal of the process safety system is to prevent process safety incidents. The Center for Chemical Process Safety s Process Safety Leading and Lagging Metrics Report (CCPS, 2007b) defines a consensus from several chemical and allied processing industries for definitions of process safety incidents and process safety near misses. If an organization adopts these definitions, a... 

The CCPS Beacon Committee strives to focus the topics on what plant workers need to know in their jobs, hazards they need to understand and recognize, and actions they can take in their regular work to prevent process safety incidents. 

The object of this chapter is to help plant and project engineers understand how corrosion data are generated and used, in order to optimize chemical plant performance and prevent process safety incidents. 

PSCMS is primarily designed as a metric for tracking industry performance on process safety incidents it is not intended to be a lessons-learned database. However, if expanded to include causes and lessons learned and if more widely distributed, the data could be useful in preventing similar incidents. 

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. 

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. 

Piping and Instrumentation Diagram Probability of Failure on Demand Process Hazard Analysis Pressure Indicator Protection Layer Preventive Maintenance Process Safety Incident Database Process Safety Management Pressure Safety Valve (Relief Valve)... 

Process safety metrics are critical indicators for evaluating a process safety management system s performance. Tracking the number of process safety incidents is one common measure of performance, but merely tracking the number of incidents after the fact is insufficient to understand the system failure that allowed the incident to occur and what can be done to prevent a recurrence. More than one metric and more than one type of metric are needed to monitor performance of a process safety management system. A comprehensive process safety management system should contain a variety of different metrics that monitor different dimensions of the system and the performance of all critical elements. 

Different metrics may be used to describe past performance, predict future performance, and encourage behavioral change. They are a means to evaluate the overall system performance and to develop a path toward superior process safety performance. This is accomplished by identifying where the current performance falls within a spectrum of excellent-to-poor performance. Such information will allow executives and site management to develop plans to address the specific improvement opportunities that could lead to measurable improvement in process safety. Good process safety metrics reinforce a process safety culture that promotes the belief that process safety incidents are preventable, that improvement is continuous, and that policies and procedures are necessary and will be followed. Continuous improvement is necessary and any improvement program will be based on measurable elements. Therefore, to continuously improve performance, organizations must develop and implement effective process safety metrics. 

Leading metrics are forward-looking and indicate the performance of the key work processes, operating discipline, or layers of protection that prevent incidents. They are designed to give an early indication of problems or deterioration in key safety systems early enough that corrective actions may be taken to avoid a major process safety incident. 

In 2008 Michael Elliott and colleagues at the University of Pennsylvania Wharton Risk Center published a study ( Linking Oil and RMP Data Does Everyday Safety Prevent Catastrophic Loss ) that provided no evidence of a correlation between low Oil rates and low process safety incident rates and only marginal support for a correlation that high Oil rates might predict further high-consequence process safety events. 

Good process safety metrics will reinforce a process safety culture promoting a belief that process safety incidents are preventable, that improvement is continuous, and that policies and procedures are necessary and will be followed. Continuous improvement is necessary and any improvement program must be based on... 

Success stories can show that improved process safety can contribute to increased productivity, cost efficiencies, and reliability. Using metrics to demonstrate the nexus between process safety performance and other organizational objectives only serves to reinforce individual and organizational commitments to process safety. A good process safety system, including appropriate metrics, can help prevent events such as unplanned shutdowns. Decreasing the number of unplanned shutdowns due to equipment failures or processing aberrations are examples of where process safety and other operational activities are linked. Unplanned shutdowns create extra cost and production problems as well as increase the probability of a process safety incident. 

When the operator is expected to take action in response to an alarm to prevent a process safety incident, the operator alarm and associated action is considered a safety function. These alarms are classified as safety-related and are designed and managed in a manner that supports the allocated risk reduction. 

In spite of, or maybe because of, process industry accidents still occurring in various industries and the increasing complexity of industrial processes (especially with industrial control systems using cyber networks), the CCPS continues to push the envelope on process safety and safety in general with their Vision 2020. The purpose of Vision 2020 is to imagine what perfect process safety will look like. The vision is to have industry stakeholders to have demonstrable and actionable commitment to the competencies and processes to prevent, reduce, and mitigate process safety incidents (not just accidents). They do this through five tenets for industry and four societal themes (Center for Chemical Process Safety, 2013). Their five tenets for industry or core principles are... 

Process Safety Considerations. Unit optimization studies combined with dynamic simulations of the process may identify operating conditions that are unsafe regarding fire safety, equipment damage potential, and operating sensitivity. Several instances of fires and deflagrations in ethylene oxide production units have been reported in the past (160). These incidents have occurred in both the reaction cycle and ethylene oxide refining areas. Therefore, ethylene oxide units should always be designed to prevent the formation of explosive gas mixtures. 

Incident investigations are a part of process safety management. In investigations, lessons are learned as to how inherently safer technology could have prevented or mitigated the results. How can these learnings be disseminated such that future incidents in similar processes are avoided ... 

For over 30 years the American Institute of Chemical Engineers (AIChE) has been involved with process safety and loss control issues in the chemical, petrochemical, hydrocarbon process and related industries and facilities. AIChE publications and symposia are information resources for the chemical engineering and other professions on the causes of process incidents and the means of preventing their occurrences and mitigating their consequences. 

W. B. Howard, Case Histories of Two Incidents Following Process Safety Reviews, Proceedings of the Thirty-first Annual Loss Prevention Symposium, AIChE, New York, 1997. 

Davenport, J. A. 1983. A Study of Vapor Cloud Incidents—An Update. Fourth Interna-tional Symposium on Loss Prevention and Safety in the Process Industries. European Federation of Chemical Engineering, Sept. 1983, Harrogate, England. 

The Center for Chemical Process Safety (CCPS) defines PSM as "The application of management systems to the identification, understanding, and control of process hazards to prevent process-related injuries and incidents."... 

Process Safety Management (PSM) is the application of management systems to identify, understand, and control chemical and manufacturing process hazards and to prevent process-related injuries and incidents. 

The American Institute of Chemical Engineers (AIChE) has a 30-year history of involvement with process safety and loss control for chemical and petrochemical plants. Through its strong ties with process designers, builders and operators, safety professionals, and academia, the AIChE has enhanced communication and fostered improvement in the high safety standards of the industry. Its publications and symposia have become an information resource for the chemical engineering profession on the causes of incidents and means of prevention. 

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