Re: [SystemSafety] SIL ratings to be scrapped?

From: nfr < >
Date: Wed, 21 Aug 2013 15:48:24 +0000

ALARP has never been replaced by the safety-integrity-level concept - or by anything. ALARP represents advice offered by the UK regulator on how one might go about satisfying the legal requirement for reducing risk, and is a quasi-legal principle. The concept of SILs offers a technical approach to how risk values might be determined and categorised, and, hence, to how the required degree of risk reduction might be expressed. It is, therefore, a tool that could be used for achieving - but never replacing - an ALARP requirement.

Being such a tool, the SIL concept can be "scrapped" whenever you choose to scrap it - or you can choose never to use it at all - as long as you have other tools that can, credibly, assist you to determine, and show the achievement of, the required risk reduction - except when you use a standard that specifically calls for its explicit use.


On 21 Aug 2013, at 15:25, Chris Hills wrote:

Hi all,

I have just been taking to one of my customers who do control systems for industrial systems. They have been told by someone they are doing a system for that SIL ratings will “soon be scrapped”. Apparently “It will be replaced by ALARP”. This seems like a completely misunderstood half a message. Though usually on this sort of thing there is a grain of reality (if miss reported or miss represented) in there somewhere.

I know I have not been paying attention over the summer but I haven’t seen anything. Is there a move on any standard to change from SIL ratings for projects?



Eur Ing Chris Hills BSc CEng MIET MBCS FRGS FRSA Technical Specialist Phaedrus Systems Ltd Tel: FREEphone 0808 1800 358 Vat GB860621831 Co Reg #04120771
Http://<> chills_at_xxxxxx

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systemsafety_at_xxxxxx Received on Wed Aug 21 2013 - 17:48:38 CEST

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