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Technical risk analysis and hazard studies

Introduction

Before risk can be managed, organisations and projects must understand what could happen and what it could lead to in terms of their goals and objectives.

Risk identification and analysis should always involve the application of a system that helps us discover and understand risks. Sometimes we may need to use additional technical tools to gain further insight into the risk of a project, operation or activity.

Technical risk analysis and hazard studies cover a broad range of techniques, many of which Broadleaf offer. In particular, due to the capability and experience of several of our personnel, we focus on technical risk analysis and hazard studies that are complex, high profile, urgent, critical or where there are potential issues to manage between the stakeholders involved.

The methods we use include:

  • Structured what-if technique (SWIFT)
  • Hazard and operability study (HAZOP)
  • Failure modes and effects analysis (FMEA) and failure modes, effects and criticality analysis (FMECA)
  • Fault tree analysis (FTA)
  • Event tree analysis (ETA)
  • Safety integrity level (SIL) determination
  • Root cause analysis.

The form and timing of technical risk and hazard assessments depends on the information available at the time and the requirements of the design, construction, operations and approval authorities.

Examples of risk identification studies

A SWIFT analysis is usually performed early in the design process when there is less detailed information. The facilitator prepares a list of questions, usually starting with ‘What if…’, or ‘Could someone…’, that lead the workshop participants systematically through the design, identifying possible hazardous scenarios.

A HAZOP study is a detailed and systematic examination of a process or design, structured around a set of guidewords, to identify and assess the risks and operability problems and the existing controls. It systematically considers the potential deviations from the design intent. The standard HAZOP study approach is often not straightforward, particularly when it isn’t being applied to standard fluid systems. Our wide experience in planning and leading HAZOP studies across many different kinds of systems allows us to tailor the guidewords effectively and conduct HAZOP studies to provide high quality outcomes.

The HAZOP study technique is also readily and successfully applied to other systems such as control systems (CHAZOP studies) and electrical systems. It can also be applied to other systems and processes that can be tested through consideration of deviations from the design intent, such as procedures, organisational changes and contracts. Three members of the Broadleaf team are involved in updating the international standard, IEC 61882 Ed 2 Hazard and operability studies (HAZOP studies) – Application guide and two were major contributors to ISO 31010:2009 Risk Assessment Methods.

Figure 1 shows a section of a drawing that was subjected to a HAZOP study led by Broadleaf.

Figure 1: Section of HAZOP study drawing

Photo credit: Geoff Raymond

It is critical that the design of a system has been reviewed prior to any HAZOP study conducted on it. Broadleaf often facilitates such design reviews.

FMEA involves reviewing the components, assemblies, and subsystems of a design to identify failure modes, and their causes and effects. FMECA is a similar study, but takes into account the criticality of each failure and assesses the risk associated with the failure mode; this is usually a qualitative process, but sometimes quantitative methods are used as well.

Examples of risk analysis studies

Fault tree analysis and event tree analysis are tools that allow the causes of a failure (FTA) or the development of the consequences of a failure (ETA) to be represented. Failure rate data and probabilities allow FTA and ETA to be used to calculate the frequency of a failure or the likelihood of a particular consequence for comparison with acceptance criteria.

Figure 2 shows a simplified example of a fault tree for the failure of a pump at a coal terminal. Figure 3 is the linked event tree.

Figure 2: Example fault tree

Figure 3: Example event tree

We conduct safety integrity level or SIL studies, but our activities are usually limited to the calculation of the required SIL and not the complete verification process. A SIL study can be very effectively linked to a HAZOP study or FMECA.

Associated studies

We conduct fire safety studies (FSS), often required as part of the approval process for new developments. An FSS can identify the sources of fire and explosion, evaluate the consequences and outline the prevention, detection and protection systems required.

We also undertake detailed root cause analyses, for both failures (accidents and incidents) and successes. The aim of root cause analysis is to understand how existing controls worked (or failed to work) and to develop actions to ensure similar successes are repeated and similar failures are avoided. As well as generating lessons from the success or failure, our approach to root cause analysis concentrates on how the organisation can learn from its past experiences.

Related international standards

Many of the techniques noted above are described in more detail in international standards.

IEC 60812 Failure mode and effects analysis (FMEA)

IEC 61025 Fault tree analysis (FTA)

IEC 61882 Hazard and operability studies (HAZOP studies) - Application guide

IEC 62502 Analysis techniques for dependability – Event tree analysis (ETA)

IEC 62740 Root cause analysis (RCA)

IEC/ISO 31010 Risk management – Risk assessment techniques

Related case studies

  • Identifying failure modes in an oil refinery process unit

    Alkylation increases the high-octane outputs of an oil refinery to enhance the value of gasoline products. Alkylation reactions are catalysed by strong acids, hydrofluoric acid (HF) in this case. The dual hazards of flammable hydrocarbons and HF mean ensuring safety is more challenging in HF Alkylation units than in a refinery in general. We used Failure Modes, Effects and Criticality Analysis (FMECA) to help a refinery identify hazardous failure modes in its HF alkylation unit and agree priorities for attention.

  • Reliable power for a remote mine

    Broadleaf was engaged to facilitate a workshop to examine the risks related to the reliability of power supply to a mine. The mine generated its own power that supplied its facility as well as surrounding communities. A planned mine expansion meant that the power supply to the plant needed to be upgraded and its reliability improved. This case discusses the importance of tailoring the criteria for risk assessment, using several forms of analysis to set priorities, and the need for a broad perspective.

  • Bridge operations on a commuter road

    This case study outlines a risk assessment and treatment options for enhancing the reliability of an opening bridge on a commuter road, augmented by aspects of failure modes and effects analysis (FMEA). The case discusses the importance of site familiarisation, setting workshop agendas carefully, adapting the risk management process to enhance its effectiveness, using a flexible approach to setting priorities for management attention, and the value of templates for efficiency, effectiveness and due diligence.

  • Land use near a major hazard facility

    When a proposal to build an aged care facility was received by a local council, a nearby major hazard facility lodged an objection to it. The council asked Broadleaf to investigate whether or not the objection was justified, and to be an expert witness in a formal public hearing. Our expertise in land use safety planning and regulatory requirements was useful in this process. In particular, we were able to guide the council to ask the right questions of the owner of the refinery to achieve a satisfactory planning outcome.

  • Fire safety for a gas drainage plant

    This case describes an investigation into the fire safety requirements of a plant processing methane-rich waste gas from nearby mines. It demonstrates the value of tailoring the fire safety advice for the circumstances. In this case, instead of a detailed quantitative assessment of all possible fire scenarios, a comprehensive qualitative review of the fire scenarios and the general principles for their management was undertaken.

  • Options for mine ventilation

    This case describes a fast, high-level review of mine ventilation options. It used Kepner Tregoe analysis to focus on the ability of the options to achieve project goals, providing clarity and a sound rationale for management decisions. If straightforward approaches are sufficient, then there is no need to over-complicate the process or invest effort in greater detail.

  • Providing water for a mine

    A preliminary hazard and operability (HAZOP) study of a mine expansion project identified potentially major risks associated with a large water pipeline near a village. A simple scenario-based risk assessment, conducted quickly by a small team, generated a range of improvement options for pipeline design and construction. Simple approaches can generate excellent results when used appropriately. It is important not to short-cut the risk management process by eliminating any of the steps, but the steps themselves can be tailored according to the project’s scope and need.

  • Business risks in an oil refinery

    We conducted a risk assessment for the management team at an oil refinery. The primary objective was to identify risks to the refinery as a business and develop an agreed priority listing of them. A subsidiary objective was to expose the management team to the risk management process. The management team wanted confidence for themselves and their major shareholders that the main risks to the business had been identified and were being managed well.

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