Hazard analyses

Change analysis 5 Every planned or new facility, process, material, or equipment is fully reviewed by a competent team, along with affected workers 

Hazard identification (job and process analysis) 5 A current hazard analysis exists for all jobs, processes, and material it is understood by all employees and employees have contributed inputs into the analysis for their jobs 

Injury/illnesses analysis 5 Data trends are fully analyzed and displayed, common causes are communicated, management ensures prevention, and employees are fully aware of trends, causes, and means of prevention 

Hazard analysis is a technique used to examine the workplace for hazards with the potmtial to cause accidents. The information obtained by the hazard idmtiiicalion process provides the foundation for making decisions upon which jobs should be altered in order for the worko- to paform the w k safely and expeditiously. In addition, this process allows workers to become more involved in their own destiny. For some time, involvement has been recognized as a key motivator of people. This is also a positive mechanism in fostering labor/management cooperation. This is especially true if everyone in the workplace is continuously looking for potential hazards that can result in mjury, illness, or evai death. 

Hazards analysis can get sophisticated and go into mnch detail. Where the potential hazards are significant and the possibility for trouble is quite teal, such detail may well be essential. However, for many processes and operations—both real and proposed—a solid look at the operation or plans by a variety of affected people may be sufficient. 

Hazard analysis is a technique used to examine the workplace for hazards with the potential to cause accidents. Hazard identification, as envisioned in this section, is a worker-oriented process. The workers are trained in hazard identification and asked to recognize and report hazards for evaluation and assessment. Management is not as close to the actual work being performed as are those performing the work. Even supervisors can use extra pairs of eyes looking for areas of concern. 

Workers may already have hazard concerns and have often devised ways to mitigate the hazards, thus preventing injuries and accidents. This type of information is invaluable when removing and reducing workplace hazards. 

Suggest what the company could do. Use a form similar to the one found in Table 4.3. 

Poisonous plants Neutrons Gamma rays X-rays 

Dusts or powders Electrical energy Capacitors Transformers Energized circuits Power lines Batteries Exposed conductors Static electricity Lightning Welding 

A hazard analysis has identified the following failures and maloperations which may give rise to a runaway reaction .  

Heating/ control system failure such that step 3 (and therefore step 4) occurs when the temperature is significantly below 80°C. -  

Failure to stop addition of reactant in step 4 after 1500 kg have been added. 

Wash-water remaining in reactor at the start of the next batch. 

Heat flow calorimetry indicated that failure of the heater control to switch off and of cooling water to switch on (case (e)) was not a problem, since the steam heating is unable to exceed 100°C and, for this semi-batch reaction, the total temperature increase only reduces further any reactant accumulation. This means that cases (b), (f) and (d) are all worse than case (e). 

Method Title Analysis of Cyromazine and Melamine Residues in Animal Tissues 

Required Protective Equipment Safety glasses, plastic gloves, lab coat.  

Procedure Steps C. Reagents Hazards Recommended Safe Procedures 

Disposal Procedure Acetic acid Hydrochloric acid AmmQnium hydroxide Sodium hydroxide See above. Flush down sink with lots of water. Use separate sink for acid vs caustic. 

The objective of the review of hazard analysis is to determine the adequacy of protection of the nuclear power plant against internal and external hazards with account taken of the actual plant design, actual site characteristics, the actual condition of SSCs and their predicted state at the end of the period covered by the PSR, and current analytical methods, safety standards and knowledge. 

For the relevant hazards, the review should demonstrate, by using current analytical techniques and data, either that the probability or consequences of the hazard are sufficiently low so that no specific protective measures are 

Organizations can use a variety of processes to analyze workplace hazards and accident causal factors. Hazard evaluations and accident trend analysis can help improve the effectiveness of established hazard controls. Routine analysis enables an organization to develop and implement appropriate controls for hazardous processes or unsafe operations. Analysis processes rely on information collected from hazard surveys, inspections, hazard reports, and accident investigations. This analysis process can provide a snapshot of hazard information. Effective analysis can then take the snapshots and create viable pictures of hazards and accident causal factors. 

Establish the norm. (What should have happened ) 

Identify, locate, and describe the change. (What, where, when, to what extent ) 

List the possible causes and select the most likely causes. 

The fault trees for even a simple process unit will be complex, with many branches. Fault trees are used to make a quantitive assessment of the likelihood of failure of a system, using data on the reliability of the individual components of the system. For example, if the following figures represent an estimate of the probability of the events 

The probabilities are added for Or gates, and multiplied for And gates so the probability of flooding the vaporiser is given by  

The data on probabilities given in this example are for illustration only, and do not represent actual data for these components. Some quantitive data on the reliability of instruments and control systems is given by Lees (1976). Examples of the application of quantitive hazard analysis techniques in chemical plant design are given by Wells (1996) and Prugh (1980). Much of the work on the development of hazard analysis techniques, and the reliability of equipment, has been done in connection with the development of the nuclear energy programmes in the USA (USAEC, 1975) and the UK. 

The Centre for Chemical Process Safety of the American Institute of Chemical Engineers has published a comprehensive and authoritative guide to quantitative risk analysis, AIChemE (2001). 

Several other texts are available on the application of risk analysis techniques in the chemical process industries see AIChemE (2000), Frank and Whittle (2001) and Kletz (1999b). 

---

ITACCP. See Hazard analysis critical control point. 

The purpose of hazard analysis and risk assessment ia the chemical process industry is to (/) characterize the hazards associated with a chemical facihty (2) determine how these hazards can result in an accident, and (J) determine the risk, ie, the probabiUty and the consequence of these hazards. The complete procedure is shown in Figure 1 (see also Industrial hygiene Plant safety). 

The hazard analysis and risk assessment procedure can be appHed at any stage in the lifetime of a process or procedure including research and... 

There are a large number of standard methods suitable for each stage in the hazard analysis and risk assessment procedure. The selection of the proper method depends on several factors. Some of these are the type of process, the stage in the lifetime of the process, the experience and capabiUties of the participants, and the step in the procedure that is being examined. Information regarding the selection of the proper procedure is available in an excellent and comprehensive reference (1). 

Hazard analysis does have limitations. First, there can never be a guarantee that the method has identified all of the hazards, accident scenarios, and consequences. Second, the method is very sensitive to the assumptions made by the analysts prior to beginning the procedure. A different set of analysts might well lead to a different result. Third, the procedure is sensitive to the experience of the participants. Finally, the results are sometimes difficult to interpret and manage. 

For chemical faciUties in the United States, hazard analysis is not an option if inventories of hazardous chemicals are maintained in amounts greater than the threshold quantities specified by the Occupational Safety and Health Administration (OSHA) regulation 1910.119. Many faciUties are finding that hazard analysis has many benefits. The process or procedure often works better, the quaUty of the product is improved, the process experiences less down time, and the employees feel more comfortable in the work environment after a hazard analysis has been completed. 

Methods for performing hazard analysis and risk assessment include safety review, checkhsts, Dow Fire and Explosion Index, what-if analysis, hazard and operabihty analysis (HAZOP), failure modes and effects analysis (FMEA), fault tree analysis, and event tree analysis. Other methods are also available, but those given are used most often. 

Safety Review. The safety review was perhaps the very first hazard analysis procedure developed. The procedure begins by the preparation of a detailed safety review report. The purpose of this report is to provide the relevant safety information regarding the process or operation. This report is generally prepared by the process engineer. A typical outline for this report follows. 

An important part of hazard analysis and risk assessment is the identification of the scenario, or design basis by which hazards result in accidents. Hazards are constandy present in any chemical faciUty. It is the scenario, or sequence of initiating and propagating events, which makes the hazard result in an accident. Many accidents have been the result of an improper identification of the scenario. 

Conduct Hazard Analysis and Risk Assessment. Ahazardis any biological, chemical, or physical property that may cause an unacceptable consumer health risk. AH of the potential hazards in the food chain are analyzed, from growing and harvesting or slaughtering to manufacturing, distribution, retailing, and consumption of the product. 

Many companies use worker—management teams, suggestion boxes, consultant surveys, suppHer training sessions, and other methods to reduce risk of injuries (see Hazard analysis and risk assessment). The principal regulatory burden falls on wastes and discharges which leave the plant (3,53,54). 

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 ... 

Process Hazards Analysis. Analysis of processes for unrecogni2ed or inadequately controUed ha2ards (see Hazard analysis and risk assessment) is required by OSHA (36). The principal methods of analysis, in an approximate ascending order of intensity, are what-if checklist failure modes and effects ha2ard and operabiHty (HAZOP) and fault-tree analysis. Other complementary methods include human error prediction and cost/benefit analysis. The HAZOP method is the most popular as of 1995 because it can be used to identify ha2ards, pinpoint their causes and consequences, and disclose the need for protective systems. Fault-tree analysis is the method to be used if a quantitative evaluation of operational safety is needed to justify the implementation of process improvements. 

Of these, the failure logic can easily be the most demanding. The simplest approach is to stop or hold on any abnormal condition, and let the process operator sort things out. However, this is not always acceptable. Some failures lead to hazardous conditions that require immediate action waiting for the operator to decide what to do is not acceptable. The appropriate response to such situations is best determined in conjunc tion with the process hazards analysis. 

A process hazards analysis is intended to identify the safety interlocks required for a process and to provide the following for each ... 

The process hazards analysis is conducted by an experienced, multidisciplinary team that examines the process design, the plant equipment, operating procedures, and so on, using techniques such as... 

Diversity is recognized as a useful approach to reduce the number of defects. The team that conducts the process hazards analysis does not implement the safety interlocks but provides the specifications for the safety interlocks to another organization for implementation. This organization reviews the specifications for each safety interlock, seeking clarifications as necessary from the process hazards analysis team and bringing any perceived deficiencies to the attention of the process hazards analysis team. 

Assure that the initial implementation comphes with the requirements defined by the process hazards analysis team. 

---