Re: [SystemSafety] SIL ratings to be scrapped?

From: SPRIGGS, John J < >
Date: Fri, 23 Aug 2013 09:56:04 +0000


The SILs of the Defence Standard were different from those of IEC61508, which fact I have seen cause problems on more than one project... I would not be at all surprised if the chattering classes take a DEF.STAN. change made almost a decade ago as an indicator of an imminent change in 61508. From: systemsafety-bounces_at_xxxxxx Sent: 23 August 2013 10:41
To: Bielefield SafetyList
Subject: Re: [SystemSafety] SIL ratings to be scrapped?

It is possible that this rumour might relate to the current work underway to revise Def Stan 00-55, Requirements for Safety Related Software in Defence Systems.

A system of SILs was defined Def Stan 00-56 Issue 2, Safety Management Requirements for Defence Systems (1996), which was also used in Def Stan 00-55. However, SILs were removed from the mandatory part of 00-56 in Issue 3 (2004) as part of the move to a goal-based approach to requirements setting. Instead, the guidance in 00-56 Part 2 discussed setting integrity requirements in generic terms, rather than using a specific SIL scheme. However, the guidance made it clear (in Annex C, section C.2) that SIL schemes could still be used where they were suitable.

Def Stan 00-55 was made obsolescent by the release of 00-56 Issue 3, and has not been re-issued. However, new work is currently underway to revise both standards. I have not seen recent drafts, but it is likely that neither standard will define a system of SILs, or require use of a specific SIL scheme. That said, it is also likely that use of suitable standard that incorporates SILs or a similar concept could still be part of the argument to demonstrate compliance with either 00-55 or 00-56.

Regards,

          James Inge



Sent: 21 August 2013 16:59
To: safetyyork_at_xxxxxx Subject: Re: [SystemSafety] SIL ratings to be scrapped?

I think there may have been a misunderstanding somewhere along the way here.

UK MoD implemented the use of SILs into many of their projects a few years ago and these are now being replaced by SIRs - Safety Integrity Requirements ( High / Medium / Low) . . . Don't know if this is a pointer in any direction . . .

        Many Thanks
        Regards
        Alan
        Alan G. Dominey
        Electrical Safety Engineer
        Torpedo Capability Contract Project Surveillance Manager
        Spearfish Safety Group

+ BAE Systems, Maritime Services
Building 31, Broad Oak Business Park,
Airport Service Road, Portsmouth, Hampshire. PO3 5PQ United Kingdom

( Direct Dial: +44 (0) 23 9251 5499

7     Fax: +44 (0) 23 9222 6922
[cid:image001.jpg_at_xxxxxx
       www.baesystems.com<http://www.baesystems.com/>

         BAE Systems Integrated System Technologies Limited
         Registered Office: Warwick House, PO Box 87, Farnborough Aerospace Centre, Farnborough, Hants, GU14 6YU, UK.
         Registered in England & Wales No: 3456325

         P don't print this e-mail unless you need to

         This email, together with any attachments, is for the exclusive and confidential use of the addressee(s).
         Any other distribution,         use or reproduction without the sender's prior consent is unauthorised and strictly prohibited.
         If you have received this message in error, please notify the sender by email immediately and delete the message from your
         computer without making any copies.  All reasonable precautions have been taken to ensure no viruses are present in this e-mail.
         BAE SYSTEMS Electronics Limited cannot accept responsibility for loss or damage arising from the use of this e-mail or
         attachments and recommend that you subject these to virus checking procedures prior to use.



Sent: 21 August 2013 15:26
To: 'Bielefield Safety List'
Subject: [SystemSafety] SIL ratings to be scrapped?

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?

Regards

     Chris

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://www.phaedsys.com<http://www.phaedsys.com/> chills_at_xxxxxx



If you are not the intended recipient, please notify our Help Desk at Email isproduction_at_xxxxxx immediately. You should not copy or use this email or attachment(s) for any purpose nor disclose their contents to any other person.

NATS computer systems may be monitored and communications carried on them recorded, to secure the effective operation of the system.

Please note that neither NATS nor the sender accepts any responsibility for viruses or any losses caused as a result of viruses and it is your responsibility to scan or otherwise check this email and any attachments.

NATS means NATS (En Route) plc (company number: 4129273), NATS (Services) Ltd (company number 4129270), NATSNAV Ltd (company number: 4164590) or NATS Ltd (company number 3155567) or NATS Holdings Ltd (company number 4138218). All companies are registered in England and their registered office is at 4000 Parkway, Whiteley, Fareham, Hampshire, PO15 7FL.






The System Safety Mailing List
systemsafety_at_xxxxxx Received on Fri Aug 23 2013 - 11:56:22 CEST

This archive was generated by hypermail 2.3.0 : Tue Apr 23 2019 - 02:17:06 CEST