Overview of System Safety and Hazard Analysis Techniques (hats)

We live in a world comprised of systems and technologies that have permeated through nearly every aspect of modern life. Ericson argues that from an engineering perspective, almost all aspects of existence can be considered as systems (2005). For instance, the author highlights examples like automobiles, electrical power grids, and commercial aircrafts. The usage of such arrangements improves the quality of life by providing efficient and reliable services. However, despite such advantages, the structures are associated with diverse risks and mishaps, especially in the event that they fail to work as required or cause accidents during their operation.

In order to understand the danger evaluation, it is important to define two key terms: mishap risk and system safety. On the one hand, the former notion describes the possibility of an entity to fail to work and in effect, resulting in death, damage, or injury. On the other hand, system safety defines the processes of formally identifying and controlling mishap risks. As such, priority is given to the identification and mitigation of such dangers in order to ensure security and minimization of perils.

Popović and Vasić describe hazards as potential conditions that can lead to blunders and accidents (2008). The writers note that they can be predicted early through identification and prevented by the elimination approaches. Further, Pine explains hazard analysis as a process of determining pileups associated with an arrangement or its operational environment, documenting unwanted consequences, and examining their possible causes (2009). Roughton and Crutchfield also add that the inspection is suitably undertaken in three types of contexts: during the development of a system, when examining a planned structure to determine if it can be certified, and when evaluating an operational scheme to improve its safety levels (2016).

Ericson outlines seven key hazard analysis techniques (HATs): preliminary hazard list (PHL), preliminary hazard analysis (PHA), requirements hazard analysis (RHA), subsystem hazard analysis (SSHA), system hazard analysis (SHA), operating and support hazard analysis (O&SHA), and health hazard analysis (HHA) (2005). The author indicates that each safety program is comprised of different activities. He also claims that in the PHL process, analysts list all types of dangers that can be associated with the identified concept. As such, the operation is undertaken at the start of the inspection in order to find anything that can go wrong in either functioning or implementation. However, the researcher describes PHA as the initial stage in the process where the system is described, energy sources identified, and historical sources outlined. As such, it is deployed either in the conceptual phase or in an existent operational structure.

With the RHA process, the analyst proceeds to document the requirements of safety design for the given system (Ericson, 2005). In addition, this involves developing security guidelines from generic standards and regulations not related to a specific peril. The fourth process, SSHA, is undertaken when an arrangement is built of several subsystems. On balance, Ericson evaluates each component to inspect blunders linked to it in order to determine how their abnormal operation affects the entire scheme.

On the contrary, SHA considers the hazards arising from functioning of the overall system as well as how it impacts the subsystems. In general, it serves as input to the SHA (Ericson, 2005). On the sixth stage named O&SHA, the researcher examines setbacks associated with procedures, personnel, equipment, and environment. Thus, the analysis is conducted concerning different activities such as testing, support, and installation among others. Finally, HHA highlights health hazards and assesses any identified materials with a view to advocate for protective measures to reduce their risk to minimal levels.

Basu points out the importance of analysis in ensuring safety for individuals involved (2017). In addition, such inspection leads to compliance and the mitigation of dangers. Current paper employs 7 HAT techniques in evaluating a missile system in order to further enhance its security.

A hydraulic fracturing manifold (“missile”) can be described as an arrangement of flow fittings and valves installed downstream of the frac pump header and upstream of each frac tree being served by it (“Frac manifold systems”, 2016). The system’s main purpose is to route water, proppants (sand), and chemicals to the underground well thereby creating the necessary pressure to fracture geological formations with a view to extract oil and gas.

From the figure, four main sub-systems making up the missile are identified. These are wellhead, high pressure pumps, blender, and frac trucks. In a typical oil extraction process, the first phase involves vertical drilling to depths of up-to 10,000 feet below the surface. The author notes that it proceeds until a “pay zone” region is reached where horizontal drilling is done up to 10,000 feet. Thus, more than one well can be dug minimizing the destruction of the surface environment.

A steel casing is fitted to the bore and cement added in order to avoid interacting with any underground water sources such as aquifers. In the well completion phase, a connection is made between the reservoir rock containing oil reserves and the cemented casing (Chapa, 2017). For this reason, a perforating gun filled with explosives is lowered to the cemented bore and fired to create holes through the cemented casing into the target rock.

In the blender, water, chemicals, and sand are mixed to create the frac fluid. More elements are used to prevent sand from settling. The substance is then pumped at high pressure by pumps on the frac trucks in order to crack the underground reservoir rock. The cracks are then held open by the kernels thereby allowing oil and natural gas to flow through the cemented casing onto the surface reservoirs.

Concerning the photograph, valves providing access to the missile are shown. Different hoses are connected from trucks to the mechanism in order to route the frac fluid to the underground well.

Discussion of Analysis Methodology

According to Ericson, the preliminary hazards list (PHL) is the starting point of all subsequent analyses (2005). As such, it outlines all potential risks that may exist in a system. In the current case study, the PHL process was adopted in identifying the different components of a hydraulic fracturing manifold that had a potential to fail during implementation.

In the PHA process, the system’s safety critical areas are determined, and perils connected with them evaluated. Furthermore, safety criteria are outlined. The researchers posit that PHA evaluation should detail the following aspects at the minimum: hazardous components, considerations on safety, environmental constraints, different test procedures, and recommended approaches to be adopted.