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.
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. 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. We conduct fire safety studies FSS , often required as part of the approval process for new developments. SWIFT uses structured brainstorming in a facilitated workshop where a predetermined set of guidewords timing, amount, etc.
At the heart of a SWIFT is a list of guidewords to enable a comprehensive review of risks or sources of risk.
At the start of the workshop the context, scope and purpose of the SWIFT is discussed and criteria for success articulated. The list of guidewords is utilized by the facilitator to monitor the discussion and to suggest additional issues and scenarios for the team to discuss. The team considers whether controls are adequate and if not considers potential treatments. Often the list of risks generated can be used to fuel a qualitative or semi-quantitative risk assessment method, such as an FMEA is.
A SWIFT Analysis allows participants to look at the system response to problems rather than just examining the consequences of component failure. As such, it can be used to identify opportunities for improvement of processes and systems and generally can be used to identify actions that lead to and enhance their probabilities of success.
What—If Analysis is a structured brainstorming method of determining what things can go wrong and judging the likelihood and consequences of those situations occurring. The answers to these questions form the basis for making judgments regarding the acceptability of those risks and determining a recommended course of action for those risks judged to be unacceptable.
An experienced review team can effectively and productively discern major issues concerning a process or system. Lead by an energetic and focused facilitator, each member of the review team participates in assessing what can go wrong based on their past experiences and knowledge of similar situations.
The facilitator and process owner can choose any guide words that seem appropriate. Guidewords usually stem around:. If your organization has invested time to create root cause categories and sub-categories, the guidewords can easily start there. Quality professional with 20 years of experience.
Gamer and storyteller with forty years of practice. View all posts by Jeremiah Genest. You are commenting using your WordPress. You are commenting using your Google account. Additional questions can always be added to the discussion list as they are raised. The SWIFT study leader needs to be aware that this is not an unusual occurrence during the discussions of the initial questions. By applying his experience, the leader may further reduce the study time by selectively changing the order of discussion of the questions posed by the team.
By first considering those questions which appear to involve the most severe potential consequences, the team can often make a more comprehensive recommendation which covers many of the same issues which will be identified during the discussion of the remaining questions. Just as in a HAZOP, if the team is not satisfied with the level of protection or otherwise perceives a need for further analysis, recommendations for further action should be proposed for management consideration.
Such recommendations need to include a brief description of the potential hazard, a description of what equipment, instrumentation or procedures currently in place are relied upon to prevent the development of the hazard and finally, the objectives which must be achieved to provide a solution to the potential problem.
Care should be taken to provide enough factual information but not too many specific details of how the correction should be implemented. This provides the designers with as much flexibility as possible in providing a solution which will meet the objectives necessary to eliminate or manage the potential hazard.
It is important to remember that as with HAZOP a member of the SWIFT team has the responsibility of identifying and adequately explaining to management what hazards might be present and taking responsibility for moving forward with any recommendations.
Recommendations should always remain flexible. They should clearly state the perceived deficiency and the objectives which the team considers important for eliminating or managing the hazard.
Ideas for a potential modifications which came to mind during the discussions can and should be documented, however, care must be taken not to state them in such a manner that can be construed as the only solution to the identified problem or as binding upon management. The procedure described above should be carried out for each question category. If so, the questions should be posed and answered. When the analysis of a system or subsystem is complete, the procedure is repeated for any remaining sections until the agreed upon scope has been completely and satisfactorily addressed.
To wrap up the study of the major system section, the leader should direct the team in reviewing and updating their thoughts on each of the regulatory requirements which were used to initiate the discussions.
Finally, the review of an entire unit or plant may consist of a series of several studies, each having a scope comparable to the typical major section just described. The organisation of the report and follow up should be handled in a manner identical to that used for HAZOP. Printer-friendly version PDF version. A description of the technique, including its purpose.
When it might be used. Advantages, disadvantages and limitations to the defence sector or the particular domain. Advantages The technique is efficient because it generally avoids lengthy discussions of areas where hazards are well understood or where prior analysis has shown no hazards are known to exist.
It is very flexible, and applicable to any type of installation, operation or process, at any stage of the lifecycle. It is quick, because it avoids repetitive consideration of deviations. It uses the experience of operating personnel as part of the team. If the subject matter experts are not available for the SWIFT session their questions can be gathered in advance and included in the checklist. The checklists used are robust as the questions asked intuitively cover historical incidents that have happened in the past.
Disadvantages Adequate preparation of a checklist in advance is critical to achieve completeness. Its benefit depends on the experience of the leader and the knowledge of the team.
SWIFT relies exclusively on the knowledge of the participants to identify potential problems. If the team fails to ask important questions, the analysis is likely to overlook potentially important weaknesses. Reviewing a what-if analysis to detect oversights is difficult because there is no formal structure against which to audit.
Most what-if reviews produce only qualitative results; they give no quantitative estimates of risk-related characteristics. This simplistic approach offers great value for minimal investment, but it can answer more complicated risk-related questions only if some degree of quantification is added for example using Risk Matrices. Sources of additional information, such as Standards, textbooks and web-sites.
US Coast Guard Website - www. Additional comments. Sample Checklist The basic structure of the SWIFT system as developed originally for the process industry translates well to the marine industry.
Operating Errors and Other Human Factors This section is too broad to derive a specific checklist in advance. Base and vessel crew — manning levels Task characteristics, information and workload Errors slips, lapses, mistakes and violations Ergonomics and work environment Training and competence Management, organisation — shift patterns, procedures, Personal Protective Equipment Work practices permits, testing, maintenance, inspections.
Emergency Operations Procedures: Clear definitions of emergencies Implications for operations Communications changed roles, specific duties conflicts, equipment, etc.
Night, poor weather, etc. Flow rate: litres per minute Team Members:. Potential collision between tanker and receiving ship. Operating Errors and other Human Factors Operator connects up to thw wrong tank on the receiving ship.
Possible overfill of ship storage tank. Operator training and competence. R1 Ensure that destination fuel tank is correctly configured before starting transfer. This should be independently checked.
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