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RES Newsletter December 2018.pdf

Roger Lim is the principal consulting engineer at Plant Safety Solutions. He has postgraduate qualifications in robotics and 40 years’ experience in the OH&S industry. Roger will share his thoughts about risk assessment in machine safety standards at a REBOK lunchtime webinar on Tuesday 9 March 2021. Register here. What sort of risk assessments are involved in machinery safety standards and why are they important? AS/NZS 4024.1-2019 gives overall guidance in safety design for machines. It includes assessments of the safety related parts of control systems – including emergency stop controls, interlock guards and presence sensing systems. Safety systems might also include non-physical barriers such as light curtains (presence sensing systems) and safety scanners. If someone actuates the emergency stop or opens the interlock gate into a machine cell and the interlock switch fails, the machine may not stop. Applying the standard and risk assessments can prevent system failure, and avoid machines causing injuries or deaths. The risk assessment method requires designers to include any reasonably foreseeable abnormal condition which might lead the operator to misuse the system. The safety system should be efficient and capable of a quick recovery after a safety stop. A cumbersome system might be an incentive for the operator to take shortcuts or defeat the safety system. Can you give me an example of how changing technology and manufacturing techniques are affecting risk assessments for machine safety? Collaborative robots are a good example. Unlike traditional industrial robots, which are physically segregated from operators, collaborative robots work in close proximity to people. Robots can do a lot of processing functions efficiently, but when they interact with humans they must be restricted. In terms of safety requirements, it becomes a major consideration and a safety assessment is required. Can you tell me more about how standards are used to assess the machinery safety risks of collaborative robots compared to industrial robots? AS 4024 provides a risk matrix which includes three elements of risk – severity, frequency (and/or duration of exposure) and possibility of avoiding the hazard. From those elements, the matrix recommends an appropriate category of control system. For collaborative robots, the severity of injury may be reversible (for example, minor cuts and bruises). For industrial robots, the severity of injury will normally be irreversible (for example, crushing or death). That changes the category of the control system all together. The categories of control system range from 1 to 4, based on a low to high risk requirement. For example, in Category 1 single safety functions might fail due to a single element failure, and should only be used for well-tried, low-risk machinery. A Category 4 control system will still perform even if it experiences cumulative faults and should be used for higher risk machinery. Industrial robots are generally Category 3. Do standards include any other methods for assessing risk for machinery safety? While the categories of control systems in AS 4024 are based on failure modes, a more recently adopted method performs a similar assessment based on performance level. Performance level is the average probability or dangerous failure per hour. For example, a Category 3 recommendation for an industrial robot would correspond to Performance Level d, with a probability of failure between 0.0000001 to 0.000001 per hour. This is a very safe system. For more advanced technology and complex electronics such as Safety PLCs, risk can be assessed using safety integrity levels (SIL). (There are other similar applications, for example, automotive safety integrity levels as defined in ISO 26262-9:2018 for road vehicles). Who do you think would benefit from your webinar? My webinar will be applicable to all safety personnel, design engineers, installers and system integrators. I will show the risk assessment matrix from AS 4024 and give examples on how to select the severity, frequency and possibility of avoidance for machinery safety. This will include the assessment of categories and assessment of application performance levels. When using the standard, design engineers will choose the appropriate category, and system integrators will validate the performance level. The risk assessment method may be quite simple, but the validation of complex electronic systems will require more technical involvement by the system integrators.

David Skegg is a chartered Fellow and life member of the Australian Institute of Health and Safety and former lecturer at the Central Queensland University Accident Forensics Laboratory. He’ll share his thoughts about mapping systems resilience at a REBOK lunchtime webinar on Tuesday 15 December 2020. Register here. What is systems resilience and how is it different to reliability and redundancy? Resilience is the ability of a system to give you a desired outcome in abnormal circumstances. This is different to redundancy and reliability. A reliable system will give you a consistent output within the parameters of its design. A resilient system goes beyond this by providing an acceptable output even in circumstances that weren’t considered in the design. Redundancy makes a system more reliable by duplicating system components. For example, the Boeing 747 has four engines even though it can fly on one. This means it has one chance in a billion of critical systems failure. It doesn’t necessarily make it a resilient system, though. Why is systems resilience important for engineers? Engineers need to consider what they want their systems to do in abnormal circumstances. Many designs, particularly those for electrical and mechanical systems, include a failsafe mechanism. This causes the system to shut down in unexpected conditions which could cause an accident. But this isn’t resilience. Resilient systems continue to work safely when things don’t go as predicted. This includes situations where people do unpredictable or dangerous things. Can you give an example of a resilient system? One current example is the ability of small businesses such as coffee shops to pivot from the way their usual practices and continue to trade under COVID-19 restrictions. Another example is the process medical practitioners go through when deciding to prescribe medication to patients. Medical practitioners base their systems and thinking on the probability that the medication will have the desired effect on the patient’s condition. However, they allow for variables such as dosages and patients’ physiology, and try to make sure the treatment will still have an acceptable result if these variations come into play. On the other hand, medical equipment is usually designed for reliability rather than resilience. How can we get better at designing resilient systems? In a perfect world, systems would never fail, but our world is not perfect. Just think of the number of systems which need to work together and absorb variations to have a successful mobile phone conversation. Nassim Nicholas Taleb wrote about a concept called the ‘Black Swan’. This is an event that you can’t forecast, which has catastrophic outcomes. If your system is sufficiently resilient, Black Swans can’t occur. This is because the system is capable of absorbing all of the variations of all of its parts. Erik Hollnagel’s work in functional resonance analysis is also useful. It allows for complexity, because we live in a very complex system. Who do you think would benefit from your webinar? My webinar will focus on ways to measure systems resilience. The secret is measuring over specific time intervals. The method I’ll discuss is establishing a grid of functional system components. Managers will benefit, as it will help them understand how best to allocate resources to make sure their systems can cope with the shock of the unexpected. It will also help them think about how much resilience they want to build into their systems and why. Engineers will also benefit, as it will help them understand how to design and monitor resilient systems.

Dr Tristan Casey is a Lecturer at Griffith University’s Safety Science Innovation Lab. He’ll share his thoughts about the social psychology of risk at a REBOK lunchtime webinar on Tuesday 17 November 2020. Register here. Why is it important for risk engineers and managers to consider how social and organisational psychology affects risk? Safety and risk are socially constructed ideas. There are tools that we can use to calculate risk with some certainty. But the knowledge, experience, beliefs and biases of the person using the tool will affect the results. I see my role as helping technical people to bring their expertise to the fore and making sure they think deeply about their assumptions and anything they may have overlooked. This helps them make better quality decisions around risk. Can you give some examples of how social and organisational psychology might affect workplace safety? Things can go quite dramatically wrong if we’re not familiar with how social psychology can influence technical decisions. I’m sure a lot of people are familiar with the NASA Challenger and Columbia space shuttle disasters. What we’ve found by unpacking those incidents is that engineers were trying to raise concerns about safety and risk to their senior managers, but organisational factors such as priorities, constraints and pressures shaped the managers’ response to those risks and led to the warnings going unheeded. Could you tell me about the concept of psychological safety? This has been getting lots of attention. It refers to a climate or atmosphere that makes it safe to engage in controversial discussions, disagree with the majority, or voice an unpopular opinion. A top-down leadership style is not so conducive to creating the right atmosphere. If managers are more consultative and ask for feedback from their teams, they can support them to be successful in communicating and mitigating hazards and frustrations in the workplace. It’s about flipping our idea of what makes an effective leader in a modern organisation. How can engineers and managers use social psychology to improve the quality of their decision-making around risk? In the last five or 10 years, we’ve been moving towards building capacity to make organisations safer and more successful, rather than focusing on what can go wrong. Engineers and managers can learn how to take advantage of social psychology to make their communication clearer and more influential. For example, they can use their knowledge of cognitive biases such as ‘groupthink’ to facilitate more equal information sharing and participation during risk workshops and meetings. Who do you think would benefit from your webinar? Risk engineers and safety practitioners. It would also benefit practitioners partnering with frontline workers to understand how they are implementing planned work and managing risk. This will be a very practical, hands on webinar with practices that people can take back to their workplaces. I’ll be aiming to improve the audience’s understanding of social phenomena such as team climate, personal biases, and our need to fit in with a group. These factors can be helpful when forming new or high performing teams with strong identities. If we have something to say that doesn’t fit in with the group, these factors can be counterproductive. I’ll also look at the history of social psychology, how it fits in with safety management, and where it’s at today – including current challenges such as COVID-19.

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