Risk analyses

Risk analysis refers to techniques for identifying, characterizing, and evaluating hazards. The identification of risk, defined in Eq. (12.1), and risk analysis found their way into many applications where they can add value in prioritization and management processes. The application of general risk analysis principles to help prioritize and manage the inspection program for plant equipment, now commonly referred to as risk-based inspection (RBI), is one of the newest applications of risk principles [3]. Some examples of risk criteria and associated units are shown in Table 12.1. 

In this equation the POP is either based on failure frequency or on remaining lifetime, while COF is usually related to safety, health, environment, and economics issues. 

Data required for developing a risk assessment program are often acquired during the analysis of failed components and systems. However, conducting a failure analysis is not an easy or straightforward task. Early recognition of corrosion as a factor in a failure is critical, since much important corrosion information can be lost if a failure scene is altered or changed before appropriate observations and tests can be made. 

Financial risk (business impact) Outage cost/day 

Investment risk (asset damage) Equipment cost/m  

AU of life involves risk Saying hello to your mate in the morning is a risk. 

Finally, while the first preference would be to eliminate all risks, a risk management strategy should be established that identifies what level of risk can be tolerated and controlled. 

The three steps of risk assessment are hazard identification, risk analysis, and risk evaluation. Only once these processes have been completed can a total risk profile be compiled. 

A hazard can be defined as a situation or action that has potential for injury, damage to property, harm to the environment, or all three. Once the hazard identification process is complete and the hazards have been analyzed, a risk analysis follows. 

A risk analysis can be defined as the calculation and quantification of probabilities, frequencies, and consequence as a result of a risk. 

Risk analysis is the scientific measurement of the degree of danger in an operation and is the product of the frequency and severity of undesired events. It sometimes views the probability, severity, and frequency of the event. 

Risk analysis provides a predictive method of projecting the risk and analyzing the possible occurrence, the probability of occurrence, and estimating the consequences. 

Objective Provide a basis to judge the relative likelihood (probability) and severity of various possible events. Risks can be expressed in qualitative terms (high, medium, low) based on subjective, common-sense evaluations, or in quantitative terms (numerical and statistical calculations). 

Allows judgement to be made concerning facilities and routes, for probable hazard and severity of consequences  

Assembles quantitative facility information concerning possible release scenarios  

Allows priorities to be recorded according to community concerns and opinions  

Judgement may be based on the accident history, type of facility, storage conditions, control technologies in place, and other factors. 

The findings from the PhD hold important implications for EU regulators and stakeholder organisations. In terms of evaluating their roles and responsibilities in risk management, four major questions have emerged  

Do existing management practices promote a culture of responsible chemical use  

Should a regulator or stakeholder organisation raise public concerns over a potential chemical risk if it cannot provide a potential risk management solution  

1 For instance, Sweden recently adopted an approach to achieve zero traffic accident fatalities or serious injuries by 2020 even though politicians and regulators recognise that some road accidents cannot be avoided [577]. 

2 A zero-risk approach such as phasing out the use of a substance can backfire if the regulatory institutions or the individuals working within the institution cannot differentiate between prescriptive and objective elements of policy. In particular, a zero-risk approach can cause inefficient and ineffective prioritisation of regulatory and corporate resources (Section 4.4.1). 

Once the hazard identification process is complete and the hazards have been analyzed, a risk analysis follows. 

A risk analysis involves a probability analysis, frequency analysis, and an impact analysis. It helps reduce uncertainties as much as possible because it provides all available information on which to base risk reduction activities. 

A probability analysis asks What could happen here  

We all share the expectation that food will be safe to eat. However, the opportunities for food to become contaminated by chemicals at some stage in its production are legion. Nevertheless, incidents of chemical contamination are very rare and this is testimony to systems for risk assessment and risk management that are applied by food producers, processors and retailers. 

Any reliable system for assessing and controlling chemical risks must contain six key elements whose relationships are described in Fig. 2.1  

Hazard identification. It is necessary to be aware of what chemical contaminants might occur in a particular foodstuff and the nature of the harmful consequences to human health that might be associated with them. 

Dose-response characterisation. Different chemicals will be associated with different toxicological end-points and the risk of any individual experiencing toxicity is related to the dose that they receive. Very often it is 

Exposure analysis. The amount of any chemical that an individual is exposed to will depend upon the levels that occur in food and the amounts of those foods that are consumed. Different population groups will often have different levels of exposure and it is therefore necessary to identify such sub-groups. 

Everyone in the engineering profession is familiar with Murphy s Law, If anything can go wrong, it will . I also prefer to remember the extended version which states, If a series of events can go wrong, it will do so in the worst possible sequence . Risk analysis is a sort of Murphy s Law review in which events are analyzed to see the destructive nature that they might produce. 

Risk analysis is a term that is applied to a number of analytical techniques used to evaluate the level of hazardous occurrences. Technically, risk analysis is a tool by which the probability and consequences of accidental events are evaluated for hazard implications. These techniques can be either qualitative or quantitative. 

Risk analysis can be broken down into four main steps  

Before safety measures are applied to a facility, it is prudent to identify and evaluate the possible hazards that may evolve before spending considerable amounts on protection that may not be needed or overlooking requirements for protection measures that are needed. The first step in fire protection engineering should therefore be to always identify the major risks at a facility. When conducting these analyses it is prudent only to only consider credible events. Farfetched or outlandish event considerations (e.g., a meteor striking the facility) are not necessary or practical and lead to a less cost effective approach. 

Safety is a quiet situation resulting from the real absence of any hazard [7]. 

Absolute safety (or zero risk) does not exist for several reasons first, it is possible that several protection measures or safety elements can fail simultaneously second, the human factor is a source of error and a person can misjudge a situation or have a wrong perception of indices, or may even make an error due to a moment s inattention. 

In common language, security is a synonym of safety. In the context of this book, security is devoted to the field of property protection against theft or incursion. 

The accepted risk is a risk inferior to a level defined in advance either by law, technical, economical, or ethical considerations. The risk analysis, as it will be described in the following sections, has essentially a technical orientation. The minimal requirement is that the process fulfils requirements by the local laws and that the risk analysis is carried out by an experienced team using recognized methods and risk-reducing measures that conform to the state of the art It is obvious that non-technical aspects may also be involved in the risk acceptation criteria. These aspects should also cover societal aspects, that is, a risk-benefit analysis should be performed 

A risk analysis is not an objective by itself, but is one of the elements of the design of a technically and economically efficient chemical process [1]. In fact, risk analysis reveals the process inherent weaknesses and provides means to correct them. Thus, risk analysis should not be considered as a police action, in the sense that, at the last minute, one wants to ensure that the process will work as intended. Risk analysis rather plays an important role during process design. Therefore, it is a key element in process development, especially in the definition of process control strategies to be implemented. A well-driven risk analysis not only leads to a safe process, but also to an economic process, since the process will be more reliable and give rise to less productivity loss. 

The number of reported incidents and accidents has been higher for electrosurgery apparatus than other electromedical instrumentations. One reason for this is that it is made for therapeutic interventions with use of high RF power, implying that wire lengths of 2—3 m do exhibit strong antenna effect. 

The whole patient is electroactive in monopolar mode. The RF potentials of many body segments may easily attain some tenths of volt rms, and insulation of these body segments is critical. The current path in the body is much shorter in bipolar modus, this is therefore a preferred lower risk modus. 

Unintended tissue destruction occurs at tissue constriction sites where the current density is high. Burns can occur at current densities above about 100 mA/cm in 10 s. Peak voltage above 3 kV due to high crest factors in coagulation makes the insulation critical and high voltage insulation breakdowns may result in tissue bums. 

An electrosurgery unit is a 2—300 W radio transmitter in the medium wave band around 1 MHz and connected to antenna wires of about 3 m lengths. In coagulation mode the power is strongly pulsed with peak powers of 1 kW or more. In fulguration modus, the contact between active electrode and tissue is to a large extent by electric arcs, which in themselves are powerful noise transmitters. 

High-frequency current used in electrosurgery does not result in living tissue excitation. However, electric arcs imply a local rectifying effect generating nerve and muscle excitation in the very vicinity of an arc. In the active electrode wire, a blocking safety capacitor is inserted so the rectified voltage shall result in only small AC low-frequency 

With the inquiry/invitation to tender on hand, the plant designer has to review whether it is a promising project, since expenses for the preparation of a complete offer may amount to a seven-digit Euro range-basically caused by labour costs. In case the supplier does not win the contract for the realization of the project, these expenses will be in vain. 

Some aspects to clarify in advance are the current utilization of the project planning department as well as the expected utilization of the execution department during the scheduled period of project execution. 

These considerations are usually followed by a risk analysis. The following risks 

Customer specification Customer specifications sometimes comprise whole filing cabinets. As already explained, such specifications often contain data and requirements that have a considerable impact on the costs. With the plant manufacturer not knowing the details of the specifications, the submittal of the quotation represents a not insignificant risk, particularly as such comprehensive specifications can hardly be read within the short period of time available. 

Commerdal part Esamples for risks included in the commercial part are high contractual penalties, the claim for Habihty for lost profit etc. 

The first step is a detailed identification of the hst of assets and operations that need protechon and the hst of possible threats. The hst of threats must encompass 

The goal is to come up with a clear and simplified stmcture of the PTO system 

The second step consists of defining several key main parameters (and then-levels) against which the threats and assets are subsequently measured. As said, definitions are based on a qualitative approach consequently, they can be adapted by the different risk assessment teams according to their needs. 

One of the main parameters used is the likelihood of a security incident to happen. Within the risk assessment methodology, likelihood is measmed by combining the probability of occurrence of an event (almost sure, very likely, possibly or unlikely) and the definition criteria of these probabilities (how often do these threats actually occur in a given time). This definition of likelihood must be applied to both types of threats PTOs face, as shown below. 

The second key parameter within the risk assessment methodology is the consequence (or impact), measured on a qualitative scale of 1-4 (sometimes 5) strong, medium, weak, no consequence. It too has to be applied to daily and severe security threats. 

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Design procedures are developed with the intention of improving the safety of equipment. Tools used in this step are hazard and operability studies and quantitative risk analysis (ORA). The following scheme may be used ... 

Mark Cook is a Reservoir Engineer and Petroleum Economist. He has worked on international assignments mainly in Tanzania, Oman, the Netherlands and the UK. His main focus is in economic evaluation of field development projects, risk analysis, reservoir management and simulation. After 11 years with a multinational company he co-founded TRACS International of which he is Technical Director. 

R. H. Richardson and J. M. Sutton, "Risk Analysis," in Proceedings of the 14th Annual Explosives Safety Seminar, U.S. Dept, of Defense, NTIS, Springfield, Va., 1972. 

Risk-Based Inspection. Inspection programs developed using risk analysis methods are becoming increasingly popular (15,16) (see Hazard ANALYSIS AND RISK ASSESSMENT). In this approach, the frequency and type of in-service inspection (IS I) is determined by the probabiUstic risk assessment (PRA) of the inspection results. Here, the results might be a false acceptance of a part that will fail as well as the false rejection of a part that will not fail. Whether a plant or a consumer product, false acceptance of a defective part could lead to catastrophic failure and considerable cost. Also, the false rejection of parts may lead to unjustified, and sometimes exorbitant, costs of operation (2). Risk is defined as follows ... 

In the simplest terms, a fault-tree for risk analysis requires the following information probabiUty of detection of a particular anomaly for an NDE system, repair or replacement decision for an item judged defective, probabiUty of failure of the anomaly, cost of failure, cost of inspection, and cost of repair. Implementation of a risk-based inspection system should lead to an overall improvement in the inspection costs as well as in the safety in operation for a plant, component, or a system. Unless the database is well estabUshed, however, costs may fluctuate considerably. 

Chemical Process Quantitative Risk Analysis Process Equipment Reliability Data, with Data Tables Technical Management of Chemical Process Safety (Plant)... 

European Commission for these and other substances by nominated dates. The toxicological data and estimation of exposure will form the basis of risk analysis and deterrnination of the appropriate restriction and control of substances in the workplace (58). Restriction of the sales of dangerous substances and preparations to the general pubHc is enforced under Directive 76/769 EC (59). 

On this basis an alternative approach to risk analysis is the parameter method [D. O. Cooper and L. B. Davidson, Chem. E/ig. Prog., 72, 73-78 (November 1976)]. 

Example 11 Parameter Method of Risk Analysis Let us consider the project outlined in Table 9-5. It is estimated that the basic data represent the most likely values and that there is a 10 percent chance that As will be reduced by more than 20 percent or will be increased by more than 5 percent. In the same way the low and high levels at 10 percent probability for Ate are considered to be 5 percent below and 25 percent above the base figures respectively. The low and high values for Cpc are considered to be 5 percent below and 30 percent above the base figure, while changes in other parameters are considered to be immaterial. 

Robert W. Ormsby/ M S / ChE / Manager of Safety, Chemicals Group, Air Products and Chemicals, Inc. Air Products Corp. Fellow, American Institute of Chemical Engineers. (Risk Analysis)... 

Government regulations reqmre hazard and risk analysis as part of process safety management (PSM) programs. These are part of the process safety programs of many chemical process facilities. 

NUREG 75/014, Washington, D.C., 1975. Rijnmond Public Authority, A Risk Analysis of 6 Potentially Hazar dous Industrial Objects in the Rijnmond Ar ea—A Pilot Study, D. Reidel, Boston, 1982. 

Introduction Theprevious sections dealt with techniques for the identification of hazards and methods for calculating the effects of accidental releases of hazardous materials. This section addresses the methodologies available to analyze and estimate risk, which is a function of both the consequences of an incident and its frequency. The apphcation of these methodologies in most instances is not trivial. A significant allocation of resources is necessary. Therefore, a selection process or risk prioritization process is advised before considering a risk analysis study. 

The components of a risk analysis involve the estimation of the frequency of an event, an estimation of the consequences (the extent of the material or energy release and its impact on population, property, or environment), and the selection and generation of the estimate of risk itself. 

A risk analysis can have a variety of potential goals ... 

The objective of a risk analysis is to reduce the level of risk wherever practical. Much of the benefit of a risk analysis comes from the discipline which it imposes and the detailed understanding of the major contributors of the risk that follows. There is general agreement that if risks can be identified and analyzed, then measures for risk reduction can be effectively selected. 

FIG. 26-4 One version of a risk analysis process. (CCPS-AIChE, 1989, p. 13 by peimission)... 

The analysis of a risk—that is, its estimation—leads to the assessment of that risk and the decision-making processes of selecting the appropriate level of risk reduction. In most studies this is an iterative process of risk analysis and risk assessment until the risk is reduced to some specified level. The subjec t of acceptable or tolerable levels of risk that coiild be applied to decision making on risks is a complex subject which will not oe addressed in this section. 

Probit models have been found generally useful to describe the effects of incident outcome cases on people or property for more complex risk analyses. At the other end of the sc e, the estimation of a distance within which the population would be exposed to a concentration of ERPG-2 or higher may be sufficient to describe the impact of a simple risk analysis. 

It is essential that good techniques be developed for identi ng significant hazards and mitigating them where necessaiy. Hazards can be identified and evaluated using approaches discussed in the section on hazard and risk analysis. 

ERPG is defined in the section on hazard and risk analysis. 

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