OCI Nitrogen, one of Europe's largest fertilizer producers, is investigating the extent to which it is possible to take targeted measures at an early stage and stop the development of major hazard accident processes. An innovative model has been developed and recently explained and elaborated in a number of publications. This current paper contains a validation of the model by looking at the BP Texas City incident in 2005. The bowtie metaphor is used to visually present the BP Texas City refinery incident, showing the barrier system from different perspectives. Not only is the barrier system looked at from its trustworthiness on the day of the incident but also from the perspective of the control room operator, and from a design to current standards of best practice. The risk reductions of these different views are calculated and compared to their original design. In addition, evidence and findings from the investigations have been categorized as flaws and allocated to nine organizational factors. These flaws may affect the barrier system's quality or trustworthiness, or may act as ‘accident pathogens’ (see also Reason, 1990) creating latent, dangerous conditions. This paper sheds new light on the monitoring of accident processes and the barrier management to control them, and demonstrates that the BP Texas City refinery incident could have been foreseen using preventive barrier indicators and monitoring organizational factors.

OCI Nitrogen wants to gain knowledge of (leading) indicators regarding the process safety performance of their ammonia production process. This paper answers the question whether indicators can be derived from the barrier system status to provide information about the development and likelihood of the major accident processes in the ammonia production process. The accident processes are visualized as scenarios in bowties. This research focuses on the status of the preventive barriers on the left-hand side of the bowtie. Both the quality – expressed in reliability/availability and effectiveness – and the activation of the barrier system give an indication of the development of the accident scenarios and the likelihood of the central event. This likelihood is calculated as a loss of risk reduction compared to the original design. The calculation results in an indicator called “preventive barrier indicator”, which should initiate further action. Based on an example, it is demonstrated which actions should be taken and what their urgency is.

OCI Nitrogen seeks to gain knowledge of (leading) indicators regarding the process safety performance of their ammonia production process. The current research determines the most dangerous process equipment by calculating their effects resulting from a loss of containment using DNV GL's Phast™ dispersion model. In this paper, flammable and toxic effects from a release from the main equipment of an ammonia plant have been calculated. Such an encompassing approach, which can be carried out for an entire plant, is innovative and has never been conducted before. By using this model, it has been demonstrated that the effects arising from an event of failure are the largest in process equipment containing pressurized synthesis gas and ‘warm’ liquid ammonia, meaning the ammonia buffer tanks, ammonia product pumps, and the ammonia separator. Most importantly, this document substantiates that it is possible to rank the most hazardous process equipment of the ammonia production process based on an adverse impact on humans using the calculated effect distance as a starting point for a chance of death of at least 95%. The results from the effect calculations can be used for risk mapping of an entire chemical plant or be employed and applied in a layer of protection analysis (LOPA) to establish risk mitigation measures.

Research question: What is the influence of general management trends and research into causes of accidents on safety management? Method: The literature study is limited to English and Dutch books, documents and articles in the scientific, professional, and technical literature from the period 1988–2010. Results and conclusions: Quite some developments occurred in the occupational safety domain. During the period concerned three models are developed, the Dutch Tripod Model, the Swedish Occupational Risk Unit Model (QARU), and the Dutch Occupational Risk Model (QRM), a barrier based model founded on the bowtie metaphor. These models address occupational accidents from different perspectives, and surprisingly similar factors. While terminology differs, these factors are called basic risk factors, situational, or management factors. Self-regulation of companies has been a strong stimulus for research on safety management systems and audits. Traditionally research in management related topics has not been part of safety research, and thus it has to be developed. While the quality of this type of research is rather low, a general structure of safety management systems is related to the Rhineland management concept. Such evidence is found in new management models such as the EFQM/INK and, to a lesser extent, Corporate Social Responsibility (CSR). While organisational learning, its quality and effectiveness on occupational safety is not researched in this period, research interests are focussing on other organisational aspects like safety culture and climate, including a renewed interest in human behaviour.

Objective: What is the influence of general management trends and safety research on managing safety? Method: A literature study which is limited to original English and Dutch books, documents, and articles in relevant scientific journals, for the period 1988–2010. Results and conclusions: Safety science does not yet have a unifying theory, which betrays its young age as a scientific discipline. In the period concerned, well-known theories, models and metaphors are established or re-issued, including the High Reliability Theory, the Man-Made Disasters and the corresponding Disaster Incubation Theory, and the Normal Accident Theory. The Swiss cheese metaphor takes its final form, the bowtie metaphor and the Drift into Danger model are published. All these theories, models and metaphors emphasize organisational aspects of major accidents in high-tech-high-hazard sectors. General management trends highlight the importance of external stakeholders, which are only reflected in the Drift into Danger metaphor. These developments must be considered in the context of a dynamic influence of external factors, like a decrease in government influence coinciding with strong market and technology developments, which can conflict with safety requirements for high-tech-high-hazard companies. Organisational/safety culture and risk/safety management systems take off during this period, both in terms of academic research and consultancy activities for companies. Whether these concepts will have a lasting influence on safety levels in companies is yet to be seen, given the unclear relationship with major accident processes. Research findings show that many companies suffer from sloppy management, having only a limited insight into possible disaster scenarios.

A Belgian manufacturing company uses pallet movers for internal transport. Despite the company's efforts to improve occupational safety, accidents with pallet movers remain noteworthy. In order to control occupational accidents, it is crucial to have a clear view of the potential accident scenarios that are present in a company. The bow-tie method is a way to capture and visualize these accident processes in an integrative way. Included in the bow-tie are safety barriers (both technical as organizational and human) and management delivery systems that can intervene in these accident processes. Once bow-ties are composed, they are an excellent point of departure to assign indicators to the safety barriers and management delivery systems in order to control (i.e., prevent or mitigate) accident scenarios. Two types of indicators can be distinguished. Firstly, there are general indicators that are assigned to management delivery systems interrupting multiple accident scenarios, which can yield a higher safety gain (as they intervene in multiple accident scenarios). Secondly, there are scenario-specific indicators targeting one specific accident scenario, which can be valuable as they target a specific problem in the company. For the development of the bow-ties, a multi-method design with the inclusion of different data sources was used, leading to a comprehensive overview. This makes the bow-tie analysis of internal transport with pallet movers transferable to other settings where pallet movers are used for internal transport.