Preliminary process safety studies

XI. Preliminary Process Safety Studies A simple what-if study is generally performed to identify major safety concerns, if any, with the project scope. FMEA (failure modes and effects analysis) or HAZOP (Hazard and operability) study can also be performed if sufficient design documents are available. Otherwise, these detailed studies will be conducted in FEED. Necessary changes are made to the project scope for mitigating any significant process safety concerns. 

In the previous chapter, it was established that in industry, plant hazards can cause harm to property (plant—machinery, asset), people, or the environment. So, it is important to develop some means of analyzing these and come up with a solution. Unfortunately, it is not as straightforward as it sounds. There are plenty of plant hazard analysis (PHA) techniques and each of them has certain strengths and weaknesses. Also each specific plant and associated hazard has specific requirements to be matched so that hazard analysis will be effective. In this chapter, various hazards (in generic terms) will be examined to judge their importance, conditions, quality, etc. so that out of so many techniques available for PHA it is possible to select which one is better (not the best because that needs to be done by experts specifically for the concerned plant) suited for the type of plant. So, discussion will be more toward evaluation of PHA techniques. Some PHA is more suited for process safety management (PSM) and is sometimes more applicable for internal fault effects [e.g., hazard and operability study (HAZOP)]. In contrast, hazard identification (HAZID) is applicable for other plants, especially for the identification of external effects and maj or incidents. HAZID is also covered in this chapter. As a continuation of the same discussion, it will be better to look at various aspects of risk analysis with preliminary ideas already developed in the previous chapter. In risk analysis risk assessment, control measures for safety management systems (SMSs) will be discussed to complete the topic. 

It seems pretty clear that the first phases of the SLC are similar in principle to the older process safety design life cycle. The main difference is the emphasis in the SLC on risk assessment in the preliminary and detailed hazard studies. This is because risk assessment leads to risk reduction, which in turn defines the SIL requirements of the safety related system. 

This preliminary study for each sterilizer is intended to define a validated sterilization procedure which is lethal and which provides a sufficient margin of safety, with respect the spores of bacterial strains known to be resistant (see examples in appendix sterilization processes using moist and dry heat ). 

Potential external events were identified by reviewing previous Safety Analysis Reports of similar DOE facilities (Restrepo 1995) and the recommended list of external events used to evaluate commercial nuclear power plant risks (NRC 1983). In addition, an attempt was made to identify any other potential external-initiating event unique to the site that had not been considered in previous studies. It is important to note that operational accidents (e.g., criticality, internal fires) occurring inside the HCF and assodated radioactive material storage facilities are not considered in this screening process. These types of "internal initiating events are identified separately using preliminary hazard checklists (see Appendix 3A). 

Characteristics of Complex Industrial Systems and Processes. WP6 - Task 6.1. Methods-algorithms for evaluating unknown parameters of system operation processes, reliability and safety models - a preliminary study. WP6 -TaskO.l.l 16.03.2009. Poland-Singapore Joint Research Project, 2007-2010. 

The effect of compatibility, morphology, rfieology, mechanical properties of mixes of polysulfones and liquid-crystal polymers are studied in Refs. [203-205]. There are several contributions on the methods of synthesizing of copolymers of polysulfones and polyesterketones and on the production of mixes [206-210]. The method for the synthesis of aromatie copolyestersulfoneketones proposed in Ref. [206] allows one to decrease the number of components used, to lower the demands to the concentration of moist in them and to increase the safety of the process. The method is in the interaction without aseotropoformer in envirorunent of dimethylsul-fone of bisphenols, dihaloydarylenesulfones and (or) dihaloydarylenek-etones and alkali agents in the shape of crystallohydrated of alkali metal carbonated and bicarbonates. All components used are applicable without preliminary drying. 

It is common practice to identify the hazard control and follow up action as a part of hazard identification and preliminary hazard analysis (discussed in detail in the next chapter). In order to control hazard, one has to look for safety interfaces also. So, the following points need to form a part of initial hazard study especially for industrial or process plants, so that entire spectrum is well-covered ... 

The work described in this paper is preliminary. The most relevant related work seems to be the attack tree approach [5]. This approach proposes to use the classical fault tree notation in order to study security. As in our work, the attack tree contains basic events representing elementary threats. In some variants of the notation, the tree also include a description of the effect security barriers. In [7] the authors propose to use an extension of the fault-tree notation in order to deal with dynamic aspects of the threat propagation. Both of the previous works tend to focus on a quantitative assessment of security requirements whereas we have been working on qualitative requirements because this would be more consistent with the Airworthiness Safety process. Another relevant approach was proposed by the CORAS project [6], this notation aims at assisting the security risk analysis. A difference between this approach and our work is that the CORAS can be applied before the security architecture is designed whereas our approach is applied once the security architecture is established. 

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