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Who’s afraid of functional safety?

Author : Harvey T.Dearden CEng, Time Domain Solutions Ltd

14 December 2011

We welcome comment from readers, we hear from Harvey Dearden........In HazardEx magazine of November 2011, Mr Stuart Nunns provides a comprehensive review of the requirement for Functional Safety Assessments in his article; ‘The art of assessing functional safety through the supply chain’.

Stuart Nunns' article in HazardEx November 2012
Stuart Nunns' article in HazardEx November 2012

In the same magazine he provides further insight into functional safety concerns with an article ‘Additional assurance for your basis of safety’, written in collaboration with Mr John Walkington.

I do not dispute the technical accuracy of these articles, but I am troubled by the despair that they (and others like them) may engender in readers from end user operations.  How on earth did we build process plants and operate them safely before ‘functional safety standards’ came along to rescue us?  If a Martian visited planet Earth and saw the extent and depth of the functional safety standards he could be forgiven for thinking we must have suffered an inordinate wave of fatalities due to functional safety failings.  In fact most fatalities within the process sector are due to much more mundane concerns such as falls from height and people taking short cuts with safety protocols.  The truth is that established good practices in design and operation of protection systems have served us well.  Yes, we may usefully refine our approaches with guidance from the functional safety standards, but we should not run away with the idea that all preceding efforts were woefully flawed; we are not obliged to rip it all out and start again.

Stuart Nunns' article in HazardEx November 2012
Stuart Nunns' article in HazardEx November 2012

The scope of the standards is so broad, and the provisions so extensive (including not just system design and equipment selection, but also project and plant management provisions), that absolute compliance in every particular is hardly to be believed.  Absolute compliance is something we approach asymptotically along a curve of diminishing returns; we may approach ever closer towards compliance, at the cost of ever increasing expenditure of resources.  There comes a point where further efforts are not warranted and would represent a serious distortion in the allocation of resources, which could be deployed to provide a better safety return elsewhere.  There will always be an ‘expert’ that can point to some shortfall, but it becomes a question of the significance of that shortfall.  This is where the professional engineer needs to exercise responsible professional judgement.  (Suitably informed and with appropriate competencies in place).  There is a real danger here of being persuaded into some very expensive but marginal activity by plausible but self-interested ‘expertise’.

The functional safety standards committees have been busy pursuing increasing degrees of rigour in the approaches they promulgate, but they might well be accused of ‘losing the plot’ in common with many other such bodies.  Similar arguments could certainly be levelled at ‘Ex’ regulation for example.  Fatal accident statistics for the UK in the five years to 2008-9 identify an average of approximately 5 deaths per year per 100,000 workers in the UK manufacturing and utility supply and extractive industries.  So the average risk per workers in these industries was 5E-5 per year.  How many of these deaths were due to failings in functional safety or ‘Ex’ affairs?  I postulate that it was a very small fraction.  If we extract the deaths from the more mundane concerns, the risk attributable to functional safety or ‘Ex’ failings is already extraordinarily low.  Interesting that in the same issue of HazardEx, Judith Hackett, Chair of the HSE says in her piece ‘Cutting costs, not corners; ‘Numerous commentators continue to state that health and safety is more often about specialists producing ever increasing very safe, tidy and ‘proper’ requirements in isolation; away from operational realities, which have left operational managers with bureaucratic systems that are not fit for purpose.’  There is in fact no legal requirement to comply with the functional safety standards.  They are however used as a benchmark by the HSE; they represent a ruler they may choose to measure you by.  The predominant concern for the HSE is to see that duty holders have brought a responsible, systematic, considered approach to these matters.  That is not the same as saying you MUST comply ABSOLUTELY.  The requirement in UK law is to reduce risk to be ’As Low As Reasonably Practicable’ (ALARP). Unfortunately, ‘practicability’ is not the watchword of these standards, rather it is ‘rigour’; a great deal of resource can be spuriously expended in pursuit of ‘rigorous’ as distinct from ‘practicable’ compliance.  

Stuart Nunns' LOPA article in HazardEx November 2012
Stuart Nunns' LOPA article in HazardEx November 2012

I do not say that these standards are without value; there is a great deal of useful guidance that can be used to inform our designs and operations (and I make a living from them!)  It does however require some discrimination to identify the critical provisions from those that would be ‘nice to have’ in an ideal world starting with a ‘clean piece of paper’ (not often that you meet one of those in this context!)  It is possible to comply with the spirit, if not the letter, of these standards in a relatively straightforward and pragmatic manner.  It becomes a question of doing what you sensibly, reasonably can.

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