integration of those devices to form the entire safety system during the design, engineering, operations and maintenance lifecycle phases. Many integrators purport to offer a safety standards ‘compliant’ FSM process, however it is important to question whether they are truly robust in technical depth, have independent certification from a recognised source such as TÜV and whether their in-house competencies are evident in their in-country location regarding systems assurance. When it comes to the equipment it is important
just applying a blanket SIL to cover an entire process. Instead, operators must first determine the requirements for individual safety instrumented functions (SIF) within a process that are necessary to protect against a specific hazardous event. Once safety functionality and safety integrity are
identified, they can then be used as the basis for designing and engineering the safety system solution. This consists of the input sensors, the logic solver and the final elements, including the functional safety management system used to successfully integrate the various SIFs into a compliant SIS. As a general rule, it is better to design risk out of
a process before installing specialised systems to control it. This will often reduce the required safety integrity level (SIL) and therefore the cost of the safety systems needed to deliver it. The systematic capability of the SIS relates to
factors such as the methodology, techniques, measures and procedures used in both the manufacturing of the safety devices used and the
to check if instruments have been certified by independent testing bodies and suitable for the specific safety related application. The equipment should have a sufficiently strong functional safety management and competency assurance system in place that can demonstrate the necessary systematic capability claims for the safety devices or integrated solution.
Assurance and savings Opting for higher integrity and demonstrable systematic capability can both save money during initial project execution and in the longer term. If an FSM is not in place at the outset of the project, this lack of ‘process’ brings with it additional issues such as extended clarifications from within the supply chain, extensive threshold quantity (TQ) requests, unexpected design changes and delays in planning, all of which impact on project management and ultimately cost. Following a defined safety lifecycle approach
means the project execution phase is optimised in terms of the impact to cost and schedule. Issues that could affect functional safety and systematic capability are identified and addressed early during FS Audits and Assessments so that the installed and commissioned SIS meets the necessary safety requirements.
• • • SAFETY IN ENGINEERING • • • In addition, the required proof test interval can
be extended significantly if equipment can demonstrate a higher HFT (Hardware Fault Tolerance) and a lower frequency of dangerous undetected failures. An SIS designed, engineered and installed in
accordance with the safety and security standards has the supporting documentation in place to rapidly ‘impact assess’ for management of change implications, operational change management and maintaining systematic capability becomes less challenging and less costly. Such a robust process will allow for efficient FS assessment, modifications and upgrades. It also provides the necessary traceability and confidence that changes to the SIS are being managed correctly. Finally, demonstrable compliance with good
practice safety standards can be critical for insurance underwriting purposes. In some cases, the ‘licence to operate’ is not agreed with the regulatory authorities until such safety assurances can be demonstrated. Ultimately it is the prevention of accidents that
still offers the biggest potential financial savings, not just in terms of financial penalties, but also the impact that an accident or incident can have on a company’s share price and reputation. Add to this the imperative to protect personnel and be a good neighbour to the surrounding community and the case for excellence in safety systems including the necessary management focus and spend on functional safety is compelling – whatever the state of the economy. So, in your organisation, when it comes to
specifying safety systems and applying industry good practice requirements, don’t be tempted to ignore the cost of functional safety as the benefits for actively seeking implementation far outweigh the significant business risk to simply ignore it.
electricalengineeringmagazine.co.uk
ELECTRICAL ENGINEERING • JULY/AUGUST 2022 23
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