Safety Life Cycle

This is the sequence of activities involved in the implementation of tire safety-instrumented systems from conception through decommissioning. 

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Figure 3. IEC 61508—the IT/DES Safety Life Cycle (from the IEC 61508 Standard)...

To structure guidance, IEC 61508 proposes a well defined safety life cycle (Figure 3). 

The result of the consideration that there are similar activities in both the security and safety life cycle, a unified approach is proposed ... 

The security life cycle of safety-related systems has to take into account the complete IT-security management life cycle as addressed in ISO 17799 and many national IT Security Handbooks, equivalent to the safety life cycle of IEC 61508. IT-Security Management is a continuous process of... 

Figure 1.17 Inherent safety life cycle. Source Wrightson [94].

The criteria 1 to 8 may be reduced, especially those requiring full application of lEC 60880. Quality assurance shall divide the development and the modification phases of the software safety life cycle into specified activities. These activities shall include all what is necessary to achieve the required software quality, to verify that this quality is achieved, and to provide objective evidence to that effect. ... 

The skills and knowledge required to implement any of the activities of the safety life cycle relating to the safety instrumented systems should be identified and for each skill, the required competency levels should be defined. Resources should be assessed against each skill for competency and also the number of people per skill required. When differences are identified, development plans should be established to enable the required competency levels to be achieved in a timely manner. When shortages of skills arise, suitably qualified and experienced personnel may be recruited or contracted. 

There are a number of approaches to providing safe application software in SISs. However, regardless of the approach used to achieve safe application software, it is assumed that the safety life cycle steps prior to application software development have been executed properly (for example, hazard and risk assessment, functional description development, equipment (hardware and software) selection). 

Which of the following methods is not usually part of the analysis phases of the safety life cycle ... 

The standards [l]-[3] concern the entire life cycle of a plant ( safety life cycle ), i.e. all activities required for realizing safety functions during a period which begins with the concept phase of a project and ends when aU safety functions are no longer available for use. In addition to quantitative requirements the standards contain numerous qualitative requirements, which are not discussed here. However, it must be borne in mind that fulfilling the qualitative requirements does not automatically lead to the quantitative requirements being fidfilled. 

As the lEC 61508 intends to be a generic standard we show in this paper how the AOP 52 can be seen as a concretization of the lEC 61508 for the domain of ammunition related software systems. Common key concepts are identified and differences are shown. We will show that the content of the AOP can be sorted and analyzed using the safety life-cycle approach of the lEC 61508. We will show how the techniques and measures suggested by AOP 52 are related to techniques and measures recommended by lEC 61508. Several topics ofcomparison which are presented in this article are based on an approach of systematic comparison of standards presented by Trebbien-Nielson and Stranden in (Trebbien-Nielson and Stranden 2001). 

Safety instrumented systems (SIS) play a major part in industrial risk management as risk reduction measures. The main European standard for functional safety of SIS, denoted electrical / electronic / programmable electronic (E/E/PE) safety-related systems, is the EC 61508 (lEC, 2005a). The second edition will soon be adopted in 2009 (EC, 2009). Objectives are to enable the design of SIS, and the development of apphca-tion sector standards. Such examples are EC 61511 (lEC, 2004) for process industry, and EC 62061 (EC 2005b) for machinery. One of the main contributions of EC 61508 is to consider the overall system and software safety life cycle. The standard fi amework, with the corresponding normative parts and subclauses, is ... 

A specification containing all the requirements of the safety functions that have to be performed by the safety-related system. It includes both what the functions must do and also how well they must do it. It is often a contractual document between companies and is one of the most important documents in the safety life cycle process. Safety Rule... 

Figure E.l represents the simple flow of the system safety process and provides a graphic summary of the materials presented in this text. This flowchart shows the typical functions of the system safety life cycle.

This International Standard sets out an approach for safety life-cycle activities to achieve these minimum standards. This approach has been adopted in order that a rational and consistent... 

NOTE 1 The term functional safety life cycle Is strictly more accurate, but the adjective functional is not considered necessary in this case within the context of this standard. 

NOTE 2 The safety life-cycle model used in lEC 61511 ANSI/ISA-84.00.01-2004 flEC 61511 Modi is shown in Figure 8. 

Persons, departments or organizations invoived in safety life-cycle activities shall be competent to carry out the activities for which they are accountable. 

NOTE As a minimum, the following items should be addressed when considering the competence of persons, departments, organizations or other units involved in safety life-cycle activities ... 

Safety planning shall take place to define the activities that are required to be carried out along with the persons, department, organization or other units responsible to carry out these activities. This planning shall be updated as necessary throughout the entire safety life cycle (see Clause 6). 

Any supplier, providing products or services to an organization, having overall responsibility for one or more phases of the safety life cycle, shall deliver products or services as specified by that organization and shall have a quality management system. Procedures shall be in place to establish the adequacy of the quality management system. 

The stages in the safety life cycle at which the functional safety assessment activities are to be carried out shall be identified during safety planning. 

Figure 8 - SIS safety life-cycle phases and functional safety assessment stages...

Where development and production tools are used for any safety life-cycle activity, they shall themselves be subject to a functional safety assessment. 

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