System Safety and Risk Assignment, Failure Mode, and Effects Analysis - Essay Example

Student Name: Tutor: Title: INTRОDUСTIОN TО SYSTЕM SАFЕTY АND RISK АSSIGNMЕNT BRIЕF Course: Introduction Safety in an organization is an essential requirement. Proper safety prevents injury or damage of personnel, equipment and materials. System safety analysis is the creation of management systems that would enhance safety of the organization and involves reports and diagrams of safety practices. This report looks at the various system safety analysis techniques and how they can be of use in improving the safety of an organization. Preliminary Hazard Analysis It is also known as potential hazard analysis. Preliminary hazard analysis is a design tool for identifying hazards, what caused them, their effects, the stages of risk and the design measures that can be undertaken to mitigate them. It provides a methodology used to identify and collate hazards available in the system as early as possible in the design. Preliminary hazard analysis is therefore done at the preliminary stage of design. Its purpose is to analyze the hazards that have been identified and to discover those hazards that had not yet been recognized at the early stages of the system that is being developed. Apart from identifying the hazards, PHA also recognizes the factors causing the hazard and their consequences. It points out the faults in the design concept and the risks associated with continued development of the concept. As PHA can be used in analyzing all categories of systems, operations, facilities and functions, it is important for organizations to put it into use so as prevent eventual losses that could have been averted had it been in use. The analysis utilizes the basic understanding it has of the system design, hazard sources and components and a preliminary hazard list. Modifications carried out in the early stages of design tend to be less costly than those made in the advanced stages of design. They are also easier in implementation. PHA therefore is an important tool in reducing costly catastrophes’ that may have occurred had a preliminary hazard analysis not been carried out. With all this capabilities PHA is supposed to be the number one technique to be utilized in the prevention and eradication of accidents and the preservation of safety at the workplace. By identifying the hazards at the work place, what caused them and their consequences PHA is provides an important function that greatly limits the negative consequences of hazards hence reducing losses from the same. (Ericson, 2005) However PHA has a few limitations which include the fact that PHA is limited by the ability of the design team to identify hazards that are in the system. PHA cannot minimize failure due to the hazard if it is not recognized. PHA does not efficiently explain existing interactions that are between hazards. Fault tree analysis The Fault Tree Analysis is a safety analysis technique in which an undesirable state of a system or organization can be analyzed to find the interactions of failures inside a system. This is done by recognizing an undesired event, resolving it into its causes and finally construction of a logical diagram showing the relationships between these events. The main aim of a fault tree analysis is to evaluate a system by identifying an unwanted or undesirable event and finding the range of events that could have precipitated that end event. It can help improve the safety of an organization by exhaustively identifying the cause of failure of a system. This allows for an organization to be familiar with all its weaknesses hence carry out a comprehensive repair of all affected sectors. The system can be upgraded after a Fault Tree Analysis test has been done to improve on all the weaknesses highlighted by the test and resolve the causes of failure. In case of an accident, Fault tree analysis can be used to find out the causes of the accident. This will be of benefit to the organization as it will allow for adoption of preventive measures against future occurrences of similar origin .The various modes of FTA, which include failure mechanisms like fatigue or shutdown failure, are used in the establishment of preventive measures against accidents hence promote institutional safety.(Booher, 2003) Apart from the fact that FTA is simple to understand, it can also deal with a combination of failures at the same time. It is also fast in showing the critical paths and provides both qualitative and measurable data for risk assessment. Its limitations include its inability to provide the cause of human error and are not realistic when dealing with systems that have a lot of safety failures. FTA also requires skilled personnel or a lot of training before its successful use. It is also time consuming. Event tree analysis (ETA) Unlike FTA which utilizes a backward looking technique, ETA identifies and evaluates the succession of events in a probable accident situation following an initiating event. The main objective of this technique being to find out if the initiating event can develop into an accident or the safety measures put into place are capable of preventing it.(Cooke and Bedford, 2001) ETA can help improve safety of the organization by developing scenarios of system failure from a single initiating event. This technique is a powerful tool that can recognize and evaluate all the consequence paths that may arise after an initiating event. This helps in the planning for a safe path of operation that is devoid of accidents or safety risks. ETA is also essential in the design process of any system. With its capability to identify risky paths of operation, this technique can be applied early in the design stage to prevent catastrophic losses later on. This will greatly benefit developers who will be able to put y in safety features instead of having to carry out corrective measures after an accident.ETA is therefore capable of reducing the price of safety by allowing early correction by use of an Event Tree that produces multiple outcome probabilities. (Ericson, 2005) Advantages of ETA are numerous and include its ability to be computerized and the availability of commercial software for its application.ETA is simple in application and can be performed on different levels of design detail. It also allows probability assessment and is methodical and structured in its approach. However ETA it is limited in its application by the fact that it has only one initiating event. Therefore, for multiple initiating events, more than one ETA is required. It is also hindered by the fact that partial failures cannot be distinguished. It also requires skilled personnel in analysis. Failure Mode and Effects (Criticality) Analysis (FME[C] A) Failure mode and effects analysis is a system safety analysis technique that carries out analysis of the system to the given level of detail and hence shows that no failure will lead to an undesirable event. It ensures that the planned activity satisfies customer expectations. It usually takes a qualitative or a quantitative approach with its focus on the risk to be taken. It utilizes engineering knowledge, consistency and institutional development techniques to optimize the operations in terms of design and production. FMEA is a valuable tool to the organization in maintaining safety of the processes and the institution as a whole. It will help in improving safety by recognizing system design potential failures even before their occurrence and hence reduce the danger of failure by either recommending design changes or different operational procedures that do are not at risk of getting compromised. When the failure has been identified, an approximation is made of when it would occur, its severity and chances of detection. The decision on the action to be taken is then made considering the analysis results. FME(C)A is an addition to FMEA where risk or criticality assessment has been included. Risk is an evaluation of a failure and the probability that it will occur. The addition of criticality assessment allows for the failures to be classified as either high risk, moderate or low risk hence prioritization can be done. FMECA is carried out on items, procedures and systems that are in an environment where failure leads to catastrophic consequences on the whole process. This is entirely true for an engineering company. This technique gives an increased comfort factor which shows that the operation shall be carried out without risks. FMECA is also important to the maintenance section of the organization as this section will use FMEA. Any important areas of the organization that could lead to a serious problem in the event of breakdown or failure will be targeted for maintenance when not in operation or when there is a reduction in the quantity of work (downtime). The importance is on minimizing the chances of failure occurring or reducing the catastrophic effects of failure. (Stamatis, 2003) Failure Mode and Effects (Criticality) Analysis is also important in determining the reliability of the products under production. In this regard it will be useful in the design and manufacturing section of the company. It will be essential in getting rid of bottlenecks and stream lining production. On the other hand FME(C)A determines all the causes and consequences be they hazardous or not hence producing a lot of unnecessary data and results. It also does not help in analyzing human error and neither does it analyze equipment hazards that are due to poor design or/and unfavorable environments. Hazard and Operability Analysis (HAZOP) HAZOP analysis is a methodical examination of operations for the objective of identifying and evaluating problems which signify risk to the organizations personnel, equipment and the operation of the system. This technique is based on the theory that teamwork in hazard analysis provides more results than single individuals working alone combine results. It also bases its application on the theory that risks are brought about by divergence from design and operating intentions. It therefore works by comparing the operation parameters against the set design conditions and presenting the consequences. It is the responsibility of team to assess the existing safe guards of the system, potential for failure and the causes that lead to failure. (Roughton and Crutchfield, 2011) It is of importance to the organization as it is significant in evaluating hazard in the organizations facilities, equipment and operations. It effectively asses the environment of operation to ensure that the system is properly situated, supported and serviced. This is accomplished for purpose of avoiding injury to the well being of people, property or the environment thus preserving safety in the organization. Another importance of HAZOP is its helpfulness in the assessment of hazards that are not quantifiable. Hazards that are complicated during detection, isolation and prediction, hazards that arise due to human nature and performance are all successfully dealt with HAZOP as it is both exhaustive and intensive in analysis. HAZOP is also recommended due to its simple and intuitive nature as compared to other safety techniques. Another advantage of HAZOP is that it has an inbuilt methodology thet is systematic and comprehensive as well as being simple to use. Conversely, HAZOP has no ways of determining hazards that are as a result of interactions between systems, procedures or processes. It is also limited in its capability of ranking the hazards and risks that are found. HAZOP also lacks the ways to determine the efficiency of the controls and safeguards that are proposed. Energy Trace Barrier Analysis (ETBA) It is also known as Barrier Analysis Energy Trace Barrier Analysis is a procedure used to increase knowledge about hazards by following the flow of energy into a system. It detects hazards by paying attention to the existence of energy in the system and ways of controlling that energy. This technique is very thorough and systematic and specifically identifies those hazards with hazardous energy supplies. ETBA is an important safety analysis technique as it enables the detection of energy sources in the design and if potentially hazardous, ETBA is used to find out if these hazards have been properly moderated by energy barriers. Energy sources may cause catastrophic damage to personnel, equipment and operations if adequate barriers are not put into place. After identifying the sort of energy in the project, establish the position at which the energy flows into or leaves and trace it through the project. Then a risk assessment is done for each superfluous energy flow before controls are recommended to curb their occurrence. This prevents the safety of the organization being compromised. ETBA is also significant in making sure the procedures used in identifying the energy hazards in the system are consistent and highly efficient. This is possible because ETBA is used to set up preliminary hazard lists and a subsystem hazard analysis. In case of accidents, it is useful in developing and comprehending damage scenarios which goes a long way in preparations of developing counter measures to these scenarios. ETBA is therefore a powerful hazard identification tool and is efficient even in complex systems. (Stephens, 2012) On the other hand ETBA is afflicted with several limitations. It does not provide a conclusive list of all the hazards present in the system and is not successful in analysis of combined hazards .ETBA is unable to recognize other classes of hazards and it may also fail in reducing or redirecting energy. Human Error Assessment and Reduction Technique (HEART) In an engineering organization, the chances of accidents or irregularities caused by human unreliability have high chances of occurrence. The Human Error and Reduction Technique (HEART) involve having an approach that helps in derivation of mathematical probabilities that are connected with error occurrence. It permits the analyst to measure the potential of human error. Heart is carried out in stages. The first stage involves determining the situation under analysis, the second step involves describing the situation, and the third step of HEART utilizes a screening process to find out the classes, sources and level of human error. The last step is where the analyst defines the strength of human unreliability found in the analyzed situation. Predictions of expected errors necessitate error minimization measures. Its advantages are that it is simple to use and requires little training and is also very quick. Every condition associated with an error has a remedial measure, HEART is advantageous also in the fact that it produces a quantitative output and needs fewer resources than other methods of determining human error like the systematic human error reduction and prediction approach (SHERPA). However, this analysis method also has a few demerits. It has been found out that HEART offers little guidance and assistance and is highly reliant on expert opinion Technique for Human Error Rate Prediction (THERP) THERP was developed to measure the rate of human error as a result of equipment unreliability and other operational characteristics that were able to influence personnel to commit an error. THERP is iterative and it is performed in five stages. The first step involves establishing the failure mode to be assessed followed by identifying the most important human operations and how they linked to the operation of the system. The third step of THERP is to approximate the rate of error for the operations by humans that are related to the evaluation. Then the consequences of the errors committed are determined before modifications of the system are carried out to minimize failure. A probability tree is the model that THERP is based on. Each branch of the probability tree portrays a task analysis. A probability is given in accordance to the occurrence or non occurrence of an event. THERP is very important in minimizing cases where human error data from one procedure is transferred to a subsequent procedure. The data provided by its tables is also useful in correction of system procedures, administrative and plant policy. This is because THERP needs a higher resolution and attaches great significance to error recovery.(Whittingham, 2012) THERP is simple in its application and is not costly. It is easy to understand as its tabulated values decrease the necessity for analytical judgment. It also minimizes variability and does not require specialized software for its application. On the other hand THERP puts a lot of emphasis on procedures and details hence exhaustive. It also gives false confidence with the assumption that it is very efficient. Its excessive details sometimes hide the exact causes of errors and it is restricted to comprehending important issues and putting forward improvements. Conclusion It is therefore safe to say that the various forms of system safety analysis techniques are unique in their own ways given their strong points and short falls and are essential in maintaining safety in the organization by providing a knowledge of all possible hazards and failures that may occur. These techniques also include human factors in their analysis therefore producing a fairly exhaustive analysis. References Stephens, R. A.,2012. System safety for the 21st century: the updated and revised edition of system safety 2000. New Jersey: John Willey & Sons. Ericson, C. A., 2005. Hazard analysis techniques for system safety. New Jersey: John Willey & Sons. Booher, H. R., 2003. Handbook of human systems integration, volume 1. New Jersey: John Willey & Sons. Stamatis, D. H., 2003. Failure mode effect analysis: FMEA from theory to execution. Milwaukee: ASQ quality press. Roughton, J. R., & Crutchfield N., 2011. Job hazard analysis: a guide for voluntary compliance and beyond. Oxford: Butterworth-Heinemann. Whittingham, R., 2012. The blame machine: why human error causes accidents. Oxford: Butterworth-Heinemann. Bedford, T., & Cooke, R., 2001 .Probabilistic risk analysis: foundations and methods. Cambridge. Cambridge university press. Read More