• • • SAFETY IN ENGINEERING • • • Why it pays to invest in safety


Quite apart from any moral considerations, skimping on lifecycle safety requirements can be an expensive mistake. David Bowers, product manager, process and DP flow at Spirit IT, explains how the right functional safety product and management systems focus can deliver long-term security and a lower life-time cost


T


he many headline-grabbing industrial disasters around the world that continue to this day prove that process and functional


safety (FS) can never be taken for granted. Aside from the sad loss of life and devastation they cause to their surrounding communities, they can also result in multi-million-dollar damages for the operators involved. While many industrial safety and cyber security


breaches have less spectacular and expensive consequences, their regular frequency is proof that too many companies are still falling short of the expected standards. Regulatory fines are just one aspect of the costs of getting it wrong. Material damage, personal injury claims and the damage to a company’s reputation can all contribute to the significant cost of a failure. With companies facing pressure to cut costs,


many find themselves subject to tightening budgets, even in areas as critical as functional safety. Safety and cyber security standards currently accepted as good practice are not actually legal requirements in many countries, leaving an obvious temptation to be sparing on safety and security system implementation which may not prove a cost-effective strategy in the long run.


Spending money and resources on equipment and Functional


Safety Management Making sure an instrumented safety system (SIS) doesn’t fail when you need it, demands a combination of good quality equipment that has been extensively tested which can then be integrated using a competency and management system with a demonstrable systematic capability (SC). It may also mean that to achieve a defined level of


safety integrity and safety functionality, the devices used in the SIS need to possess a level of redundancy and a self-diagnostic capability far outstripping that required for non-critical systems. It is worth remembering that ‘good safety is good


business’ and a little more spend on FS assurance during specification, pays dividends during the many years of operation.


Lifetime savings Managing functional safety and security is an increasingly complex challenge. The introduction of Edition 2 of the IEC 61508:2010 functional safety standard gives a higher priority to defining a


suitable, dedicated safety requirements specification (SRS) for each project. It introduces a formal stage between the


conclusion of the hazard analysis stage of a project and specifying particular SIS requirements leading into the design and engineering phase. The same focus on requirements specification can also be found within the sector standard IEC 61511:2016 Edition 2 and the associated links to SIS security risk assessment in conjunction with compliance to Standard IEC 62443. Ultimately, the SRS is intended to bring together


all the information necessary to make sure that any SIS provides the right level of performance and risk reduction without being overly complex or expensive. If safety systems are over-specified, they are likely to cost more upfront, and because of the extra complexity, require more operational management and maintenance once commissioned. Under-specification can be much more serious as the safety system may well be inadequate and unable to provide the correct level of risk reduction, i.e. one with the potential to result in a failure on demand and/or cyber security breach. Confusion can often arise when it comes to designing a safety system as it’s not as simple as


electricalengineeringmagazine.co.uk


ELECTRICAL ENGINEERING • JULY/AUGUST 2022 21


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