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#1 Posted : 02 March 2007 09:11:00(UTC)
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Posted By Adam Worth
A Friday post to separate the men from the boys :)

We are currently looking to carry out SIL assessments and were wandering if anyone had carried out SIL assessments by both Risk Graph and LOPA for the same SRCS
We have just calibrated our risk graph but before hand got trained in LOPA
We are curious as to if anybody has noticed a difference in the SIL levels that come out from these two studies? Theoretically they shouldn't be!
Our risk graph is very well calibrated but academically we suspect we get lower SIL ratings using LOPA

Plan B - Might be to Use Risk Graph as a quick screen and the LOPA for anything over SIL 2?

Thanks in advance for any comments or experience shared.

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#2 Posted : 02 March 2007 09:29:00(UTC)
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Posted By stephen williamson
Must be a boy. Ain't got a clue what you're on about.
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#3 Posted : 02 March 2007 09:39:00(UTC)
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Posted By Darren J Fraser
Agree must be a boy, as I have absolutely no idea what, if anything this is on about.

Waiting to be educated accordingly.
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#4 Posted : 02 March 2007 09:43:00(UTC)
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Posted By DaveW
Adam, Stephen....lol

I'm assuming you're referencing System Integrity Levels, Layer Of Protection Analysis and Safety Related Civil Engineering Structures.

Sorry Adam, I don't usually need to get that technical in my line of work, I work with:

MRA = Muppet Reaction Analysis
IPC = Integrated Pillock Control
DAKHTW = Does Anyone Know How This Works
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#5 Posted : 02 March 2007 09:56:00(UTC)
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Posted By Adam Worth
:)

Yes indeed system integrity levels

It's basically looking at the likely hood that a safety system will fail and that interlocks are of sufficient engineering integrity to lower the risk to a tolerable frequency

Although this is more applicable to process industries, if you have any electrical or electronic interlocks on your site they should be SIL rated

This is more applicable to safety case industry - i.e. offshore / railways etc

A quick google search gave -

http://www.hse.gov.uk/research/rrhtm/rr216.htm

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#6 Posted : 02 March 2007 11:45:00(UTC)
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Posted By Stephen Sherratt
I too am wrestling with this and have some sites that may be of interest:

www.ibf.at On this site they have a computer product call SAFEXPERT that is a systematic hazard analysis following EN 1050, EN 12100 and the selection of safety related parts of control systems to EN 954-1. I am advised that a similar product will soon be available compliant with ISO 13849-1 and BSEN 62061.

http://www.hvbg.de/e/bia/pra/index.html On this site you can obtain a free Performance Level Calculator.

http://www.pilzsupport.c...vices/training/index.htm And finally PILZ do training.

Best of luck
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#7 Posted : 02 March 2007 12:32:00(UTC)
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Posted By Tom Doyle
Adam, Stephen,
Excellent guidance. ISO 13849 Part 1 was released again in 2006. Detailed guidance is also available in the new release.
Cheers,
Tom Doyle
http://www.industrialsafetyintegration.com/
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#8 Posted : 02 March 2007 15:04:00(UTC)
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Posted By John
Just noticed this thread and seeing as I work for Pilz and run some training for the company you can call me on 07971 568 620 for further information if anyone wants.

Note: Courses are very busy and will get busier due to 13849 in future.

Kind regards
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#9 Posted : 02 March 2007 16:15:00(UTC)
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Posted By Robert S Woods
I did all this SIL stuff with some light guards and interlocks for a machine in which an operative had previously become entangled.

Did all the probability analysis etc, and there shouldn't have been an accident for 200,000 years.

I came back 2 weeks later to find someone had built a bridge made of 2 planks stood on rolls of material over the top of the light guards.

Ingenious but suicidal.
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#10 Posted : 02 March 2007 16:19:00(UTC)
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Posted By John
....and also a clear case of a poor health and safety culture with a lack of commitment from management. A case of gross misconduct if ever I heard one!
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#11 Posted : 02 March 2007 16:22:00(UTC)
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Posted By Robert S Woods
Google has made us all geniuses.
Cut and paste is a wonderful tool.
The ability to explain what you cut and paste into your postings in plain English would indeed separate the men from the boys.

Go on give it a try.
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#12 Posted : 02 March 2007 16:27:00(UTC)
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Posted By Robert S Woods
John,

all of the above. But it was quicker than the safe system of work. I just hope they make enough extra money from the increase in production to cover the downtime, fines, and raised insurance premiums which will surely follow.
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#13 Posted : 02 March 2007 16:32:00(UTC)
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Posted By Robert.
What about the good old fashioned RTFM system?
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#14 Posted : 04 March 2007 02:14:00(UTC)
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Posted By 9-Ship
WHich SIL technique you use depends to some extent on what type of safety device you are dealing with. IEC 61508 standard if looking at SIL assessments from the product/manufacturers point of view or IEC 61577? standard(process industries)- can't remember if this is the correct number

You probably won't need to bother with much after SIL 1 or 2 for normal industrial use.

SIL 3 and 4 are high risk petro-chem and nuclear instrumentation/SIS standards. SIL 4 is a very high standard of integrity and very costly/near impossible for mere mortals to achieve. Leave it to the nuclear boys.

For those not aware SIL assessment is not taught (I don't think) at NEBOSH level - you also need to get involved with FTA analysis as well. Its pretty advanced stuff - avoid it if you can the standards are not easy to understand/user friendly.
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#15 Posted : 05 March 2007 08:44:00(UTC)
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Posted By Adam Worth
Thanks Boys :)

However it still doesn't help with our decision of what method to use.

My concern is not over how to do the study by either method but to determine if the different methods have the ability to give different results?

I will look at all the links provided later today, thanks too all who provided those

What we were after were opinions based on real experience before we commit time to one method
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