Functional safety assessment

NOTE 1 Activities relating to verification, management of functional safety and functional safety assessment are... 

Functional safety assessment aims to evaluate whether provisions made during the assessed lifecycle phases are adequate for the achievement of safety. Judgements are made by assessors on the decisions taken by those responsible for the realisation of functional safety. An assessment would for example be made prior to commissioning as to whether procedures for maintenance are adequate. 

The following attributes are considered good practice for Functional Safety Assessment ... 

Where application software is used in the safety instrumented system, the functional safety assessment may include ... 

All engineering activities follow a predefined overall project work process. The development of a SIS has its own process. Individual steps are mapped into the overall process. Functional safety assessment is carried out at the appropriate stages. 

Bamert T., Kosmowski K.T., Sliwinski M. 2006. Methodological aspects of functional safety assessment. Radom Institute for Operation Technologies - National Research Institute ZEM, Vol. 4 (148) 150-176. 

Kosmowski K.T., Sliwinski M. 2005. Methodology for functional safety assessment. London Taylor Francis Group, European Safety Reliability Conference, ESREL 2005, Gdynia - Sopot - Gdansk. 

Larish, M. Hanle, A. Siebold, U. Haring, I. 2008. SysML aided functional safety assessment. Proceedings ofESREL 2008 and 17th SRA-Europe Annual Conference, Valencia, Spain, Sept 2008. 

AN EXAMPLE OF HUMAN RELIABILITY ANALYSIS AS A PART OF FUNCTIONAL SAFETY ASSESSMENT... 

Other requirements, regarding all phases, are about documentation (Part 1 5) management of functional safety (Part 1 6) functional safety assessment... 

Larisch, Matthias, Ame Hanle, Uli Siebold, and Ivo Haring. 2008. SysML aided functional safety assessment. In ESREL, edited by Martorell et al. Valencia, Spain Taylor Francis Group, London. 

In the author s experience, independent functional safety assessment is the most critical factor here. However it is also heavily aligned with lEC 61508 and may still result in insufficient focus being directed at systematic issues. 

Functional Safety Assessment is according to lEC 61508 an investigation, based on evidence, to judge the functional safety achieved by one or more E/E/PE safety-related systems and/or other risk reduction measures. ... 

In lEC 62061 it s possible for a SPECS supplier to self-assess a Safety Related Electrical Control System, but when developing a safety system such as SIL3 Hoist Monitor or the SIL3 Hoist Protector the use of a 3rd party organization to make a Functional Safety Assessment against lEC 62061 2005+Al 2012 is recommended. The 3rd party organization should be involved already when the development project starts, when the safety plan is established. 

A function check, or bump test, means using simple tests (such as exposing sensors to calibration gas or exhaling into the oxygen sensor) to show that the instrument will respond to the chemicalfs) of concern and that aU alarms operate as they were designed. Functional Safety Assessment... 

The first of the four tests causation asks whether harm could occur because of some unsafe matter on which a charge of negligence could be based. Top-down techniques are appropriate at this phase of a functional safety assessment. The worst case scenario of destruction of a fully occupied platform would be 500 fatalities. 

NOTE A functional safety audit may be carried out as part of a functional safety assessment. 

A procedure shall be defined and executed for a functional safety assessment in such a way that a judgement can be made as to the functional safety and safety integrity achieved by the safety instrumented system. The procedure shall require that an assessment team is appointed which includes the technical, application and operations expertise needed for the particular installation. 

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. 

NOTE 1 Additional functional safety assessment activities may need to be introduced as new hazards are identified, after modification and at periodic intervals during operation. 

NOTE 2 Consideration should be given to carrying out functional safety assessment activities at the following stages (see Figure 8). 

NOTE 3 The number, size and scope of functional safety assessment activities should depend upon the specific circumstances. The factors in this decision are likely to include... 

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

At least one functional safety assessment shall be undertaken. This functional safety assessment shall be carried out to make sure the hazards arising from a process and its associated equipment are properly controlled. As a minimum, one assessment shall be carried out prior to the identified hazards being present (i.e., stage 3). The assessment team shall confirm, prior to the identified hazards being present, that... 

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

NOTE 3 Functional safety assessment of tools includes, but is not limited to, traceability to calibration standards, operating history and defect list. 

The results of the functional safety assessment shall be available together with any recommendation coming from this assessment. 

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