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33-534: The HAZOP technique was initially developed for systems involving the treatment of a fluid medium or other material flow in the process industries, where it is now a major element of process safety management . It was later expanded to the analysis of batch reactions and process plant operational procedures. Recently, it has been used in domains other than or only loosely related to the process industries, namely: software applications including programmable electronic systems; software and code development; systems involving

66-625: A HAZOP should take into account the review scope, the number of nodes to be reviewed, the provision of completed design drawings and documentation and the need to maintain team performance over an extended time-frame. The team members may also need to perform some of their normal tasks during this period and the HAZOP team members can tend to lose focus unless adequate time is allowed for them to refresh their mental capabilities. The team meetings should be managed by an independent, trained HAZOP facilitator (also referred to as HAZOP leader or chairperson), who

99-534: A given order) a set of guidewords to each node in the process. To prompt discussion, or to ensure completeness, appropriate process parameters are considered in turn, which apply to the design intent. Typical parameters are flow (or flowrate), temperature, pressure, level, composition, etc. The IEC standard notes guidewords should be chosen that are appropriate to the study, neither too specific (limiting ideas and discussion) nor too general (allowing loss of focus). A fairly standard set of guidewords (given as an example

132-434: A later, detailed design HAZOP also becomes necessary. For process plants, identifiable sections ( nodes ) are chosen so that for each a meaningful design intent can be specified . They are commonly indicated on piping and instrumentation diagrams (P&IDs) and process flow diagrams (PFDs). P&IDs in particular are the foremost reference document for conducting a HAZOP. The extent of each node should be appropriate to

165-477: Is 1:5000, but nobody usually survives a plane crash, so it is far more catastrophic . On January 30 1978, a new version of US Department of Defense Instruction 6055.1 ("Department of Defense Occupational Safety and Health Program") was released. It is said to have been an important step towards the development of the risk matrix. In August 1978, business textbook author David E Hussey defined an investment "risk matrix" with risk on one axis, and profitability on

198-399: Is necessary to reduce the risks to an acceptable level. The degree of preparation for the HAZOP is critical to the overall success of the review. "Frozen" design information provided to the team members with time for them to familiarize themselves with the process, an adequate schedule allowed for the performance of the HAZOP, provision of the best team members for their role. Those scheduling

231-447: Is responsible for the overall quality of the review, partnered with a dedicated scribe to minute the meetings. As the IEC standard puts it: The success of the study strongly depends on the alertness and concentration of the team members and it is therefore important that the sessions are not too long and that there are appropriate intervals between sessions. How these requirements are achieved

264-414: Is ultimately the responsibility of the study leader. For a medium-sized chemical plant, where the total number of items to be considered is around 1200 pieces of equipment and piping, about 40 such meetings would be needed. Various software programs are now available to assist in the management and scribing of the workshop. Source: In order to identify deviations, the team applies (systematically i.e. in

297-417: Is usefully applied as a revalidation tool to ensure that unduly managed changes have not crept in since first plant start-up. Where design information is not fully available, such as during front-end loading , a coarse HAZOP can be conducted; however, where a design is required to have a HAZOP performed to meet legislative or regulatory requirements, such an early exercise cannot be considered sufficient and

330-542: The EPA , AIChE 's Center for Chemical Process Safety , or the Energy Institute . PSM schemes are organized in 'elements'. Different schemes are based on different lists of elements. This is a typical list of elements that may be reconciled with most established PSM schemes: Nwankwo, Chizaram D.; Theophilus, Stephen C.; Arewa, Andrew A. (May 18, 2020). "A Comparative Analysis of Process Safety Management (PSM) Systems in

363-624: The US Air Force Electronic Systems Center in 1995. Huihui Ni, An Chen and Ning Chen proposed some refinements of the approach in 2010. In 2019, the three most popular forms of the matrix were: Other standards are also in use. In his article 'What's Wrong with Risk Matrices?', Tony Cox argues that risk matrices experience several problematic mathematical features making it harder to assess risks. These are: Thomas, Bratvold, and Bickel demonstrate that risk matrices produce arbitrary risk rankings. Rankings depend upon

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396-406: The probability ) against the category of consequence severity. This is a simple mechanism to increase visibility of risks and assist management decision making. Risk is the lack of certainty about the outcome of making a particular choice. Statistically, the level of downside risk can be calculated as the product of the probability that harm occurs (e.g., that an accident happens) multiplied by

429-506: The "design intent" basis for the HAZOP study. For example, a prudent designer will have allowed for foreseeable variations within the process, creating a larger design envelope than just the basic requirements, and the HAZOP will be looking at ways in which this might not be sufficient. A common use of the HAZOP is relatively early through the detailed design of a plant or process. However, it can also be applied at other stages, including later operational life of existing plants, in which case it

462-499: The HAZOP team uses a list of standardized guidewords and process parameters to identify potential deviations from the design intent. For each deviation, the team identifies feasible causes and likely consequences then decides (with confirmation by risk analysis where necessary, e.g., by way of an agreed upon risk matrix ) whether the existing safeguards are sufficient, or whether an action or recommendation to install additional safeguards or put in place administrative controls

495-601: The Process Industry" (PDF) . Journal of Loss Prevention in the Process Industries . 66 . doi : 10.1016/j.jlp.2020.104171 . S2CID   219495043 . This management -related article is a stub . You can help Misplaced Pages by expanding it . Risk matrix A risk matrix is a matrix that is used during risk assessment to define the level of risk by considering the category of likelihood (often confused with one of its possible quantitative metrics, i.e.

528-470: The UK. Nowadays, regulators and the process industry at large (including operators and contractors) consider HAZOP a strictly necessary step of project development, at the very least during the detailed design phase. The method is applied to complex processes , for which sufficient design information is available and not likely to change significantly. This range of data should be explicitly identified and taken as

561-400: The complexity of the system and the magnitude of the hazards it might pose. However, it will also need to balance between "too large and complex" (fewer nodes, but the team members may not be able to consider issues within the whole node at once) and "too small and simple" (many trivial and repetitive nodes, each of which has to be reviewed independently and documented). For each node, in turn,

594-409: The contractor and the client company. A minimum team size of five is recommended. In a large process there will be many HAZOP meetings and the individuals within the team may change, as different specialists and deputies will be required for the various roles. As many as 20 individuals may be involved. Each team member should have a definite role as follows: In earlier publications it was suggested that

627-419: The design of the risk matrix itself, such as how large the bins are and whether or not one uses an increasing or decreasing scale. In other words, changing the scale can change the answer. An additional problem is the imprecision used on the categories of likelihood. For example; 'certain', 'likely', 'possible', 'unlikely' and 'rare' are not hierarchically related. A better choice might be obtained through use of

660-422: The general research from Cox, Thomas, Bratvold, and Bickel, and provide specific discussion in the realm of cybersecurity risk . They point out that since 61% of cybersecurity professionals use some form of risk matrix, this can be a serious problem. Hubbard and Seiersen consider these problems in the context of other measured human errors and conclude that "The errors of the experts are simply further exacerbated by

693-413: The harm severity can be categorized as: The likelihood of harm occurring might be categorized as 'certain', 'likely', 'possible', 'unlikely' and 'rare'. However it must be considered that very low likelihood may not be very reliable. The resulting risk matrix could be: The company or organization then would calculate what levels of risk they can take with different events. This would be done by weighing

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726-581: The movement of people by transport modes such as road, rail, and air; assessing administrative procedures in different industries; assessing medical devices; etc. This article focuses on the technique as it is used in the process industries. The technique is generally considered to have originated in the Heavy Organic Chemicals Division of Imperial Chemical Industries (ICI) , which was then a major British and international chemical company. Its origins have been described by Trevor Kletz , who

759-605: The next few years. In the same year the first paper in the open literature was also published. In 1977 the Chemical Industries Association published a guide. Up to this time the term 'HAZOP' had not been used in formal publications. The first to do this was Kletz in 1983, with what were essentially the course notes (revised and updated) from the IChemE courses. By this time, hazard and operability studies had become an expected part of chemical engineering degree courses in

792-476: The other. The values on the risk axis were determined by first determining risk impact and risk probability values in a manner identical to completing a 7 x 7 version of the modern risk matrix. A 5 x 4 version of the risk matrix was defined by the US Department of Defense on March 30 1984, in "MIL-STD-882B System Safety Program Requirements". The risk matrix was in use by the acquisition reengineering team at

825-455: The review, e.g., drawing/document corrections and clarifications. Specialist software is now available from several suppliers to support the recording of meeting minutes and tracking the completion of recommended actions. Process safety management Process safety management (PSM) is a practice to manage business operations critical to process safety . It can be implemented using the established OSHA scheme or others made available by

858-413: The risk of an event occurring against the cost to implement safety and the benefit gained from it. The following is an example matrix of possible personal injuries, with particular accidents allocated to appropriate cells within the matrix: The risk matrix is approximate and can often be challenged. For example, the likelihood of death in an aircraft crash is about 1:11 million but death by motor vehicle

891-418: The same base term, such as 'extremely common', 'very common', 'fairly common', 'less common', 'very uncommon', 'extremely uncommon' or a similar hierarchy on a base "frequency" term. Another common problem is to assign rank indices to the matrix axes and multiply the indices to get a "risk score". While this seems intuitive, it results in an uneven distribution. Douglas W. Hubbard and Richard Seiersen take

924-481: The severity of that harm (i.e., the average amount of harm or more conservatively the maximum credible amount of harm). In practice, the risk matrix is a useful approach where either the probability or the harm severity cannot be estimated with accuracy and precision. Although standard risk matrices exist in certain contexts (e.g. US DoD , NASA , ISO ), individual projects and organizations may need to create their own or tailor an existing risk matrix. For example,

957-458: The standard) is as follows: Where a guide word is meaningfully applicable to a parameter (e.g., "no flow", "more temperature"), their combination should be recorded as a credible potential deviation from the design intent that requires review. The following table gives an overview of commonly used guideword-parameter pairs (deviations) and common interpretations of them. Once the causes and effects of any potential hazards have been established,

990-419: The study leader could also be the recorder but separate roles are now generally recommended. The use of computers and projector screens enhances the recording of meeting minutes (the team can see what is minuted and ensure that it is accurate), the display of P&IDs for the team to review, the provision of supplemental documented information to the team and the logging of non-HAZOP issues that may arise during

1023-408: The system being studied can then be modified to improve its safety. The modified design should then be subject to a formal HAZOP close-out, to ensure that no new problems have been added. A HAZOP study is a team effort. The team should be as small as practicable and having relevant skills and experience. Where a system has been designed by a contractor, the HAZOP team should contain personnel from both

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1056-517: The third stage of its hazard analysis procedure (the first two being done at the conceptual and specification stages) when the first detailed design was produced. In 1974 a one-week safety course including this procedure was offered by the Institution of Chemical Engineers (IChemE) at Teesside Polytechnic . Coming shortly after the Flixborough disaster , the course was fully booked, as were ones in

1089-401: Was the company's safety advisor from 1968 to 1982. In 1963 a team of three people met for three days a week for four months to study the design of a new phenol plant. They started with a technique called critical examination which asked for alternatives but changed this to look for deviations . The method was further refined within the company, under the name operability studies , and became

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