Interface Safety Analysis

Interface safety analysis (ISA) is concerned with determining the incompatibilities between subsystems of an equipment/product and assemblies that could cause accidents. The method establishes that it is possible to integrate distinct units/parts into a viable system and that normal operation of an individual part or unit will not impair the performance of or damage another unit/part or the total system/equipment. 

The relationships considered by ISA can be grouped under three classifications physical, flow, and functional [12,14,16]. Each of these classifications of relationships is described below, separately. 

The physical relationships are concerned with the physical aspects of items/products. For example, two items/products might be very well designed and manufactured and operate quite well individually, but they 

The flow relationships are concerned with two or more units or items. For example, the flow between two items/units may involve air, steam, fuel, lubricating oil, water, or electrical energy. Furthermore, the flow could also be unconfined, such as heat radiation from one item/body to another. The frequent problems experienced with many products include the proper flow of energy and fluids from one unit to another unit through confined passages, consequently resulting in safety-related problems. 

The causes of flow-related problems include faulty connections between units and total or partial interconnection failure. In the case of fluids, the factors that must be considered with care from the safety perspective include flammability, loss of pressure, toxicity, lubricity, contamination, and odor. 

The functional relationships are concerned with multiple units or items. For example, in a circumstance where outputs of a unit constitute the inputs to the downstream unit(s), any error in outputs and inputs may lead to damage to the downstream unit(s), thereby creating a safety problem 

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Chapter 3 presents introductory aspects of safety and human factors. Chapter 4 is devoted to methods considered useful to perform patient safety analysis. These methods include failure modes and effect analysis (FMEA), fault tree analysis (FTA), root cause analysis (RCA), hazard and operability analysis (HAZOP), six sigma methodology, preliminary hazard analysis (PFfA), interface safety analysis (ISA), and job safety analysis (JSA). Patient safety basics are presented in Chapter 5. This chapter covers such topics as patient safety goals, causes of patient injuries, patient safety culture, factors contributing to pahent safety culture, safe practices for better health care, and patient safety indicators and their selection. 

Compare hazards and operability analysis with interface safety analysis. 

There are numerous methods and techniques developed in areas such as safety, reliability, and quality for conducting various types of analysis [23-25]. Some of these methods and techniques can also be used to perform rail safety analysis. These methods and techniques include fault-tree analysis, hazards and operability analysis, cause-and-effect diagram, interface safety analysis, failure modes and effect analysis, and Pareto diagram. One of these approaches (i.e., fault-tree analysis) is presented below, and information on other methods and techniques is available in Chapter 4 and in the literature [23-25]. 

Chapter 3 presents introductory aspects of reliability and safety. Chapter 4 presents a number of methods considered useful to perform transportation systems reliability and safety analysis. These methods are failure modes and effect analysis, fault-tree analysis, the Markov method, hazard and operability analysis, interface safety analysis, preliminary hazard analysis, job safety analysis, and technique of operations review. 

A very important factor in safety management and safety analysis is the recognition of the importance of the human intervention in the related activities. Human errors should be avoided by the establishment of clear interfaces between man and machine, and by the preparation of operating and emergency procedures and of maintenance rules and guidelines. Beneficial human intervention, even in extremely degraded situations, should be implemented by adequate training, procedures and simulation studies and practices. 

Chapter 10 is devoted to medical device usability. It covers topics such as medical device users and use environments, medical device user interfaces, an approach to develop medical devices effective user interfaces, guidelines to reduce medical device user interface-related errors, guidelines for designing hand-operated devices with respect to cumulative trauma disorder, and useful documents for improving usability of medical devices. Chapter 11 presents three important topics relating to patient safety patient safety organizations, data sources, and mathematical models for performing probabilistic patient safety analysis. 

It cannot be overemphasized that the O SHA is an extremely valuable analytical tool that concentrates on the human interface with the system from both operations and maintenance standpoints. Therefore, because of the critical requirement of ensuring that operations and maintenance personnel are protected from any hazards in their tasks, the importance of a properly performed O SHA is of paramount concern in the system safety analysis process. 

The safety analysis process should be based on plant design information that is complete and accurate. This information should cover aU plant SSCs, off-site interfaces and site specific characteristics. 

Task Analysis An expansion of the Job Safety Analysis (JSA) method of identifying hazards associated with a given job or task. Differs from the JSA in its level of specific detail and consideration of the human interface in all aspects of the job performance. 

It has already been pointed out that the computer based system and its interfaces with the plant should be evaluated at various phases of the development for their potential contribution to hazards at plant level (possible techniques are outlined in Section 8.3.9 of Ref [4]). When such potential critical behaviours ate identified, they should be traced into the computer system design, the software design and the code in order to identify parts of the design and of the software that necessitate special design features. In addition, these hazards should be traced back into the requirements and should be incorporated into the plant safety analysis as appropriate. 

The analysis focused on identrQeation of novel interfaces and their further safety analysis, where novel interfaces are defined as ... 

System Conceptualisation, Representation and Scoping (System Analysis). This stage of the analysis is often omitted from safety literatnre and standards. This preparatoiy phase is necessaiy in order to provide a stmctured framework and systematic approach for the hazard identification, risk assessment, and for snpporting a holistic approach to the analysis. Some form of system description model, for example state transition model or sequence and collaboration diagrams, should be used as the basis for hazard identification, as the hazards resulting from each system interface, process or interaction can be elicited. The novel approach, developed as part of the research, to system conceptualisation in support of safety analysis, is discussed later in the book ... 

The Initial Change Safety Analysis (ICSA) is done at two levels. Firstly, when the system definition is estabhshed, each of the boundary interfaces identified within the process models should be subjected to ICSA as already discussed earlier. This is essentially a stmctured review process, wherein interfaces ate systematically reviewed by a group of experts against predefined criteria as explained earlier. 

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