The new EN ISO 13849-1 machinery safety standard places the onus on machine builders to demonstrate that all necessary risk assessments have been completed and documented. Andrew Ryder, an expert in machinery safety at Bosch Rexroth, follows the audit trail.
The new EN ISO 13849-1 machinery safety standard may well have passed many machine builders in the UK by, but it would be misguided for them to assume that all responsibility for safety continues to rest with the end-user.
EN ISO 13849-1 is a significantly more complex and time consuming standard to administer in comparison to the earlier EN 954-1, particularly in terms of the risk assessment procedures and technical file documentation that machine builders will be required to store and provide to customers on the relevant authorities, when necessary.
EN ISO 13849-1 uses a risk graph to accurately assess the Performance Level required (PLr) by the new standards. It also requires the machine builder to identify the Performance Level achieved by designing, assessing, modelling, calculating and then evaluating the machine in line with the standard.
The danger for machine builders is the temptation to take short-cuts with the new standards and award themselves the CE mark, in the knowledge that it is the end user who is usually the focus of any investigation into a workplace accident.
This would be a mistake as, in the event of an accident, the end user or the Health and Safety Executive (HSE) is likely to ask for evidence that the machinery operates in line with the new directive. This should detail all potential risks and the steps taken to mitigate them.
The key to compliance with the new directive is to design out any risk before the machine is built. Completing a risk assessment once a machine is in service is likely to prove too late and very costly. This will be a cultural and mindset change for engineers which will prove uncomfortable for many, but the benefits of this approach will become clear over time.
So what practical steps do machine builders need to take to ensure compliance with EN ISO 13849-1?
At the heart of EN ISO 13849-1 lies risk assessment. Depending on the machinery this can range from mechanical hazards, through to working at height issues, the risk of electrical shock, through to the potential for a platform to cause serious injury.
The scale of the risk assessment and technical file that needs to be produced to satisfy any potential inspection by the HSE can be demonstrated by using the example of an electrically controlled height adjustable platform, of the type used widely across industry.
Fortunately, there are a number of software packages available, including the Bosch Risk Assessment Tool, which can help machine builders collate and store the relevant information.
The first stage of the risk assessment is to determine when the potential risk event is likely to occur. This could be during the manufacture of the machine, its transportation, assembly, commissioning, maintenance, de-commissioning, disassembly and end-of-life disposal.
Danger zones during all of these life-cycle phases need to be identified. These could be doors, chains, lifts, electric and electrical cabinets. All the different areas which could cause danger need to be assessed by the relevant experts in design, manufacture and engineering.
Next we must determine the type of hazard that the machine could potentially pose. This could be mechanical, electrical, noise related, vibration, up to and including an ergonomic hazard for the operator. For a height adjustable platform this could range from an employee being run over by the platform through to crushing, shearing, slipping, tripping or falling; through to sharp angles, edges or spikes and even suffocation.
Once potential risks have been assessed, each individual risk has to be examined separately and documented in line with any relevant standards. With crushing for example, the hazard description is that the platform could be lowered onto an employee, bystander or technical staff during operation. The root cause can be defined as personnel inadvertently entering the area below a platform, perhaps to retrieve some dropped hand tools or during maintenance of the drivetrain.
A risk score is then awarded which identifies the severity of the risk, potential exposure, the probability of the risk occurring and the potential for avoidance. Using the platform example, a fall would be given a high score given that any injury has the potential to be fatal.
Exposure of an operator to the risk needs to be assessed along with the potential frequency, designated on an hourly, daily, weekly or annual basis.
The individual measures implemented to avoid any risk event then need to be documented. For example, with a platform, measures such as bump strips applied to all edges and the centre of the platform, an audible siren to indicate platform movement and warning signs can all be designed into the final machine.
In terms of technical protection, the measures taken could include isolation of the platform during maintenance of the drivetrain and warning signs indicating the area of a hazard. The speed of the platform could also be limited to 25mm/second.
Finally, user information needs to be provided detailing the steps that must be taken by operators. On a height adjustable platform these could include the use of personal protective equipment and restrictions on personnel allowed underneath the platform.
My advice to any machine builders concerned at the prospect of assessing their machines in line with the new standard is to seek out expert advice. The depth of information required in the technical file means that compliance with the new standard is neither an easy matter nor a quick one. However, ensuring compliance from the design stage is likely to save machine builders significant time and cost in the long run compared to retrospective attempts to comply once a machine is in service and being marketed to customers.
For further information on Rexroth log on to www.boschrexroth.co.uk.
