Case studies incidents

Each chapter starts with a description of the topic covered in the chapter. This is followed by a short example highlighting a reported incident involving a batch reaction system. The case study is followed by a listing of key issues and process safety practices unique to the topic. The issues and concerns presented in this book, as well as potential design solutions and sources of additional information are presented in the tables. This format concisely conveys the necessary and relevant information in a familiar and convenient format. The organization of the tables is described below. 

The following case study illustrates the use of SCREEN. In this example we analyze a fire incident that occurred at a wood preserving facility. The incident involved a fire and explosion of six cylindrical vessels containing creosote and pentachlorophenol. Refer to Figure 15. 

A. Kalelkar, Investigation of Large Magnitude Incidents Bhopal as a Case Study, Preventing Major Chemical and Related Process Accidents, Symposium Series No. 110, Institution of Chemical Engineers, Rugby, UK, 1988. 

Generally speaking, typical major incident conditions correspond to a release of some ten thousands of kilograms of some hydrocarbon at the site of a chemical plant or refinery that is characterized by the presence of obstructed and partially confined areas in the form of densely spaced equipment. The relative agreement with results derived from the multienergy method indicates that application of this concept is a reasonable approach for this case study. 

On the other hand, a TNT equivalency of 3% is expected to fail in situations where typical major incident conditions do not apply. This explains why the outcomes of the two methods applied to the storage site case study differed. 

In this case study, one of the strongest blast-generating BLEVEs to occur in the Mexico City incident (Section 2.4.3, Pietersen 1985), will be investigated. This BLEVE occurred a few minutes after the initial vapor cloud explosion and probably involved two 1600-m spheres. The spheres were probably 50% full at the time of the accident. 

In the shorter case studies, only the immediate causes of the errors are described. However, the more extended examples in the latter part of the appendix illustrate two important points about accident causation. First, the precondihons for errors are often created by incorrect policies in areas such as training, procedures, systems of work, communications, or design. These "root causes" underlie many of the direct causes of errors which are described in this section. Second, the more comprehensive examples illustrate the fact that incidents almost always involve more than one cause. These issues will... 

For each of the stages of the model, Petersen (1985) provided a series of flow diagrams to assist analysts in using the model for incident analysis. These are given in Appendix 2B. The use of the model and the flow charts for detailed psychological analysis of incidents is illustrated by a case study in Appendix 2C. 

APPENDIX 2C CASE STUDY ILLUSTRATING THE USE OF THE SEQUENTIAL MODEL OF ERROR IN INCIDENT ANALYSIS... 

The purpose of this chapter is to show that improvements in safety, quality, and productivity are possible by applying some of the ideas and techniques described in this book. The fact that error reduction approaches have not yet been widely adopted in the CPI, together with questions of confidentiality, has meant that it has not been possible to provide examples of all the techniques described in the book. However, the examples provided in this chapter illustrate some of the most generally useful qualitative techniques. Case studies of quantitative techniques are provided separately in the quantification section (Chapter 5). The first two case studies illustrate the use of incident analysis techniques (Chapter 6). 

The first case study describes the application of the sequentially timed event plotting (STEP) technique to the incident investigation of a hydrocarbon leak accident. Following the analysis of the event sequence using STEP, the critical event causes are then analyzed using the root cause tree. 

In the second case study, variation tree analysis and the events and causal factors chart/root cause analysis method are applied to an incident in a resin plant. This case study illustrates the application of retrospective analysis methods to identify the imderlying causes of an incident and to prescribe remedial actions. This approach is one of the recommended strategies in the overall error management framework described in Chapter 8. 

Case study 5 provides an example from the offshore oil and gas production industry, and illustrates the fact that in solving a specific practical problem, a practitioner will utilize a wide variety of formal and informal methods. Table 7.1, which describes some of the methods used in the study, includes several techniques discussed in Chapter 4, including interviews, critical incident techniques, walk-throughs and task analysis. 

CASE STUDY 1 INCIDENT ANALYSIS OF HYDROCARBON LEAK FROM PIPE... 

This case study concerns the events leading up to the hydrocarbon explosion which was the starting point for the Piper Alpha offshore disaster. It describes the investigation of the incident using the sequentially timed events plotting (STEP) technique. Based on the STEP work sheet developed, the critical events involved in the incident are identified and analyzed in order to identify their root causes. 

The process involved in the incident is concerned with the separation of crude into three phases. The crude is pumped into a two stage separation process where it is divided into three phases oil, gas, and water. The water is cleaned up and dumped to drain. The remaining mixture of oil and gas is then pumped into the main oil line where it is metered and sent on for further processing. A simplified process diagram is shown in Figure 7.1. The case study described here is centered on a flange leak in one of the oil pipeline pumps (pump A) and its associated pressure relief valve piping. 

The case study has documented the investigation and root cause analysis process applied to the hydrocarbon explosion that initiated the Piper Alpha incident. The case study serves to illustrate the use of the STEP technique, which provides a clear graphical representation of the agents and events involved in the incident process. The case study also demonstrates the identification of the critical events in the sequence which significantly influenced the outcome of the incident. Finally the root causes of these critical events were determined. This allows the analyst to evaluate why they occurred and indicated areas to be addressed in developing effechve error reduchon strategies. 

CASE STUDY 2 INCIDENT INVESTIGATION MISCHARGING OF SOLVENT IN A BATCH PLANT 307... 

This case study illustrates how the methodologies described in Chapter 6 can be used to analyze plant incidents and identify the root causes of the problems. Based on this information, specific error reduction strategies can be developed to prevent similar incidents from occurring in the future. Also, the findings of such an analysis can provide the basis for more general discussions about the prevalence of similar error inducing conditions in other plant areas. 

CASE STUDY 2 INCIDENT INVESTIGATION MISCHARGINC OF SOLVENT 1 N A BATCH PLANT 309... 

To gather information about the factors which contributed to the above incident, interviews were held with the workers and their management. Relevant documentation such as standard operating procedures and documentation relating to the incident was also collected. A task analysis (see Case Study 3) of the job of the top floor person was carried out in order to examine the operations involved and the factors which could affect job performance. Two techniques were used for the analysis of this incident, namely variation tree analysis and root cause analysis. 

Tlie following simplified example, constructed by Hendershot, will facilitate tlie transition to tlie case studies. Suppose tliat a risk assessment is being conducted at a chemical plant to detenuine the consequences of two incidents (tlie initiating events of die event tree shown in Fig. 21.1.1) defined as... 

This case study is an example of a well blowout resulting from the neutralization of acid by carbonate rock. Kamath and Salazar181 and Panagiotopoulos and Reid182 both discuss the same incident. Although they do not specify the location, Brower and colleagues183 identify the site as the Cabot Corporation injection well, near Tuscola, Illinois. 

EUSES. As in the case of USEtox model, the present model provides outputs such as human intake fraction of a certain substance for different exposure pathways. In the present case study, estimation of the human intake doses for Guiyu was calculated. These results were compared with the incidence and severity of the effects (dose-response assessment). 

A number of surface diffraction techniques can be employed in the structural study of electrochemical interfaces, depending on the details of the system under study. For bulk materials or thick films (such that the X-ray beam only samples that layer) conventional diffraction experiments can be performed and, in fact, a number of in situ X-ray diffraction studies of this type have been reported.126 129 In the case of thin films or monolayers, two different techniques can be employed and these are the reflection-diffraction technique introduced by Marra and Eisenberger,3 ), 32 and the technique based on surface truncation rods.131 In the first case, the incident X-ray beam impinges on the sample at an angle below... 

Initially, the literature is searched for relevant data on the substance (physical-chemical properties, thermodynamics, incidents, case studies, and so forth). If insufficient data are available, the usual case, a systematic investigation procedure comprising three main subjects must be initiated for the material in question. 

---