Safety-related control systems risk assessment

In relation to previous BCSP publications about its examinations, these terms now appear more prominently environmental controls safety through design design of hazard control systems risk management and risk assessment techniques. 

If from the general risk assessment some form of Safety-Related Control Function (SRCF) is required, then there is a choice of which of the two standards (EN ISO 13849 or EN 62061) to follow in order to assess the safety requirements for each safety function and how to assess that any proposed system meets the requirements. In general if the safety protection is an electrical-based system either standard could be used. Figure 9.4 gives guidance on which is the more suitable standard based on the type of technology to be used for the safety function. 

One might argue that once a safety-related issue has been identified it is too late to consider potential controls but this is far from the case. Just because a hazardous scenario may result from the fault it is by no means a foregone conclusion that actual harm will occur. There will usually be a human operator between the system and the patient who can work around the issue or take remedial action. In some cases, the provision of practical advice to users from a system expert may alleviate much of the real world risk until the issue is hxed. Important mitigations of this nature should be documented in the issue assessment and provide one means by which the advice may be propagated. 

Any simple measurement of performance in terms of injury frequency rates or incident rates is not seen as a reliable guide to the safety performance of an undertaking. The report finds there is no clear relation between such measurements and the work conditions, the injury potential, or the severity of injuries that have occurred. A need exists for more accurate measurements so that a better assessment can be made of efforts to control foreseeable risks. It is suggested that more meaningful information would be obtained from systematic inspection and auditing of physical safe guards, systems of work, rules and procedures, and training methods, than on data about injury experience alone. (HSE, 1976)... 

It is required to manage the functional safety in entire safety lifecycle keeping the risk level of potential hazardous events at acceptable level. Thus, it is essential to modernize and improve when required the basic process control system (SCADA and DCS) and the safety-related systems including the alarm system based on experience from their operation and periodical risk assessment. In such process it is essential to consider carefully the human and organizational factors using relevant HRA methods to maintain adequate risk associated with operation of complex industrial hazardous plants. 

Discussions on risk assessment are not complete without some focus on SMS. SMS is a comprehensive and integrated system to address all aspects related to health and safety. It is to be properly documented so that this comprehensive document is accessible to all concerned. It must be compatible with the safety management objective and philosophy of the facility in question. It is mainly concerned with the control measure. It tracks errors, deviations, etc. in the control measures. It also keeps track of performance standards of the equipment and system. Therefore it is a live document and needs periodic reviews and updates. 

The aim is to ensure that those parts of a control system that perform safety functions have adequate safety performance for the application. Safety performance, as previously noted for safety integrity, relates to the reliability and fault tolerance of the safety-related parts, and their ability to provide the required level of risk reduction. It is therefore axiomatic that the process of satisfying the requirements of the standard for any particular machine starts with a risk assessment of that machine. 

The integrity of a safety-related electrical control system (SRECS) is expressed using the SIL concept. A risk assessment has to be undertaken to determine the required SIL, typically, using... 

In the field of science and research. Dr Sinay has been working with mechanical dynamics as a source of technical risks, optimization of risk management systems for technical systems and occupational health and safety, problems of control integrated systems, issues of safety and security, and with processes of quality assessment mainly in the field of university education. He has tutored thirteen doctorate students, two of them inaugurated as professors in fields related to safety and one promoted as a senior lecturer in the field of safety of technical systems. He is... 

Safety related activities should be properly planned to ensure that they can be carried out safely and effectively. Suitable and sufficient assessments of the risks to health and safety arising from particular activities should be carried out. The nature of the required risk assessment will depend on the extent of the risks involved and may be qualitative or quantitative in nature. The purpose of the risk assessment is to identify the acceptability of the proposed activity and the appropriate contfol measures required to ensure that risks are as low as reasonably achievable (ALARA). The results of the risk assessment should be incorporated into work instructions or control documentation associated with the activity, for example, the documentation for the permit to work system. 

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