Principles of Forensic Engineering Applied to Industrial Accidents

Principles of Forensic Engineering Applied to

Copyright

Dedication

I was invited to do so by an author of this book, Luca Fiorentini, member of the editorial board of the International Journal of Forensic Engineering, published by Inderscience Publishers. The topics of this book are well balanced and a good example of the focus and messaging in forensics.

Preface

The facts and their causes are written in the universe of the disaster scene, but we must understand the language and characters of the writing. This belief is the basis of the large space given in this book to case studies.

Acknowledgement

Vincenzo Puccia, director of the provincial command of the Padua National Fire Service, and Serena Padovani for their contribution on the flash fire at silo and the explosion of a rotisserie of case studies; a special thanks to Vincenzo also for his example about the value of the digital evidence, shown in Paragraph 4.4.3.1; Numerics GmbH, in the person of Ernst Rottenkolber and Stefan Greulich, for the valuable collaboration on the case study of the fragment. TECSA S.r.l., in the person of Federico Bigi, for the support in the case study of an oil pipeline that cracks; Giovanni Manzini for information regarding the case study on storage building on fire.

List of Acronyms

Introduction

Who Should Read This Book?

Going Beyond the Widget!

Technical problems and mechanical failures are the outer layers of the onion: they are the direct cause. The knowledge is complete and the perceived complexity is only visible thanks to man.

Figure 1.1 The onion like structure between immediate causes and root causes.

Forensic Engineering as a Discipline

In the previous paragraph, it was briefly mentioned that an accident investigation requires the typical multidisciplinary project management structure: this is due to the multidisciplinary approach commonly adopted. The interested reader can delve into the historical background of the scientific method by consulting [7].

Figure 1.2 Galileo Galilei (left) and Roger Bacon (right): two of the brightest scientists of the world who supported the scientific method.

When the accident involves serious injuries to people, the application of forensic pathology may be necessary [10]. This feature allows the reconstruction of the accidental dynamics, starting with the study of penetrating and perforating shrapnel, dust tattooing, heat burns, etc. These are all elements, taken here only as an example, necessary for the medical- legal opinion at autopsy.

Industrial Accidents 2.1 Accidents

Principles of Combustion

Flammable Gases and Vapors
Flammable Liquids
The Ignition

The goals of a fire investigation are twofold: determining the origin and the cause of the fire. In addition, it is important to understand that the ability of the ignition source to start a fire depends on the fuel. 3 of the Norman Atlantic in the fire, due to radiation: simulation and evidence (plastic boxes, melted at the top).

In general, an increase in temperature results in an expansion of the flammability range, with particular focus on the upper limit. The ignition is the side of the fire triangle that provides the necessary energy to start the combustion of a fuel-air mixture within the flammability limits.

Figure 2.4 The different mechanisms of heat transfer.

Fires

The most visible part of fire is the flame, whose color depends on the temperature and chemistry of the fire, and the smoke, which is an unwanted byproduct of fire. When the fire is not extinguished spontaneously, because all the fuel has been burned, the use of specific substances, called "extinguishers", is necessary. The significant presence of black soot is a key indicator of the lack of oxygen (Figure 2.10); and.

It shows the typical trend of a fire, with the emphasis on the variation of the generated power. energy per second) over time. The temperature drops due to heat dissipation from the smoke and irradiation to the coolest zones.

Table 2.8 Extinguishers and their actions.

Explosions

The propagation rate of the reaction front depends on the speed of the heat conduction. A confined gas explosion can result in an explosion or detonation, depending on the nature of the confined space. In a slow deflagration, bursting occurs at a pressure equal to the structural strength of the item.

The dust raised by the first explosion participates, greatly increasing the destructive effects of the event. To have ignition and explosion of a dust cloud, it is necessary that the concentration of the fuel between the.

Figure 2.12 Shock front and pressure front in detonations and deflagrations.

Incidental Scenarios

Toxic, flammable, or energetic releases may be the result of an incident or the cause of it. The horizontal dimension of the flames is comparable to the dimension of the spill, while the height is almost double. It is the boiling of water at depth with the indirect involvement of a significant amount of fuel.

The collapse of an LPG tank, resulting in vaporization and ignition of the tank; and. Vapor cloud explosion (VCE) and subsequent aircraft fire were two contributors to the former.

Near Misses

A near miss is different from an adverse circumstance: with this definition, a set of conditions or circumstances that have the potential to cause harm or ill health is intended. The conceptual differences between accident, near miss and undesirable circumstances are shown in the example in figure 2.22. It is important to deal with near misses as they represent unique opportunities to learn from experience without any serious ones.

They are free lessons to learn, with the aim of preventing future accidents and subsequently avoiding future damage and loss, including large costs to the companies affected by an incident.

Figure 2.22 Differences between accident (a), near miss (b), and undesired circumstance (c).

Process Safety

Management of Safety

For a long time, experience-based standards defined the process safety and loss prevention efforts of many companies. The Process Safety Management (PSM) standard from OSHA and the Seveso Directive in Europe are an example. Therefore, companies were forced to comply with the new set of national and international regulations: it is the safety management of the compliance-based process.

What makes the difference in risk-based process safety management is the use of leading indicators. A risk-based process safety management simply answers the following questions: how bad could it be?

Figure 2.23 Contributing factors in improving loss prevention performance in the process industry.

The Importance of Accidents

Seveso disaster
Bhopal Disaster
Flixborough Disaster
Deepwater Horizon Drilling Rig Explosion
San Juanico Disaster
Buncefield Disaster

Thanks to radiation, the heat was transferred from the upper wall to the surface of the liquid. Indeed, if we would have performed a fault tree analysis (FTA) to determine the probability of failure on demand (PFD) of the. The key concept is that hazard identification becomes useless if the initial hypotheses (eg the safeguards are turned on) are no longer true.

Basically, following the principles of "what you don't have, can't flow", the best solution is to have no people within the bounds of a potential incident. In the early hours of Sunday 11 December 2005, around 3.00am, the display showed a constant value, meaning it stopped recording the rising level, while the tank continued to fill.

Figure 2.28 Principles of incident analysis.

Performance Indicators

The expectation regarding the development of this indicator is a decrease in the number of open ones. The safety culture is therefore not simply the sum of the behavior of an individual actor (who acts prudently and strictly), but is achieved through a holistic approach. Some indicators related to this factor include: management deficiencies in safety instructions,

This complexity is at the root of the failure of the system, when the organization (i.e. the system of relationships between the different actors) is inadequate. The performance indicators mentioned above are intended to provide a picture of the company's overall safety level at a given point in time.

The Role of ‘Uncertainty’ and ‘Risk’

Examples of some methods related to the probability of occurrence (such as Fault Tree Analysis or Event Tree Analysis) are described in chapter , where the broad topic of human factor effects is also discussed. It is the method of time reversibility, where the objects – thought of as physical reality – are put at the center of the reasoning. Most people fear the trivial risks and underestimate the significant dangers in everyday life.

A risk in this region often requires the immediate stop of the industrial process, which is absolutely not acceptable. Briefly, this is a cost-benefit analysis of the potential intervention required to mitigate the risk to the acceptable region.

Assessment? Who is the Forensic Engineer and what is his Role?

Investigation

This is a less obvious reason found at the end of the investigation result and is related to the system. Depending on the depth of the analysis, it is possible to develop recommendations to prevent similar incidents, not just the same ones [3]. At the end of the investigation, a recommendation is developed to eliminate the problems or weaknesses that are.

The level of the investigation, i.e. how much detail the investigation should reveal; If this is the outcome of the accident investigation, it is time to hand over the investigation to the police and human resources.

Figure 3.1 Phases in accident investigation.

Forensic Engineering

The forensic engineer's activities are separate from the events he/she is trying to reconstruct. Therefore, the forensic engineer's goal is to connect these dots, trying to reconstruct the actual sequence of events leading up to the untoward incident. The application of the scientific method to establish a root cause cannot merely consist of shifting laboratory methodology to the context of reality.

Not only the position, but also the role of the investigator can influence the investigation outcomes. Forensic engineering can be specific or general in scope depending on the nature of the dispute [6].

Legal Aspects

In the legal context, the role of the forensic disciplines is to assist with evidence [20]. The role of the investigator is to testify, in deposition or in court, about the findings of his/her investigation. The judge, or the prosecutor, or the lawyer of an involved party is generally interested in [6] and [10]: the investigator's qualification for the specific incident analysis; the assumptions at the base of the.

The retention of the incident investigation reports is a controversial topic between layers, which tend not to retain them in order to limit both the legal costs and to avoid an eventual increase in the. Sometimes, depending on the regulations of the specific country, the necessity to investigate an incident is required by law.

Figure 3.4 Handling of an item under investigation.

Ethic Issues

Firstly, it is essential that proper legal assistance is provided by the organisation's lawyer throughout the investigation process. Then it is fundamental to maintain a technical focus when conducting the investigation and not to answer questions about legal responsibility (this task is the task of the legal counsel). It is also important to follow regulatory requirements on incident investigation, including internal organization procedures.

Regarding witness statements, care should be taken to avoid words that could lead others to misunderstand the content of the testimony or to question its credibility. Once the witness statement has been recorded in a document, it is suggested that the witness signs each page.