MachineBuilding
px

Fixings for fixed machine guards - further clarification

Procter Machine Safetyvisit website

 

Jeremy Procter provides further clarification of the requirements relating to fixings for fixed machine guards (the author is the Managing Director of Procter Machine Guarding, a Member of BSI's MCE/3 committee, and the former Convenor of the European Standards Committee CEN TC114 WG11 responsible for Machine Guards).

Fixings for fixed machine guards - further clarificationMachine guards can only provide protection if they are properly designed, manufactured, installed and, most importantly actually remain in place on the machine. For example, a guard cannot provide the intended level of protection if it is not replaced or not properly fixed in position after it has been removed to provide access for maintenance. For that reason, the Machinery Directive 2006/42/EC contains, within the Essential Health and Safety Requirements, three points relating to fixings:

  • fixed guards must be fixed by systems that can be opened or removed only with tools;
  • their fixing systems must remain attached to the guards or to the machinery when the guards are removed;
  • where possible, guards must be incapable of remaining in place without their fixings

However, there is still a degree of confusion surrounding these points, and some machinery safety consultants appear to have misinterpreted the requirements. Before looking in detail at these, a most important point to note is that the machine instructions should make it clear that only trained persons should be authorised to remove machine guards - and the instructions must be backed up by a safety culture in the workplace that does not 'turn a blind eye' to dangerous working practices.

What is a tool?

Regarding the use of a tool, it is well understood that fasteners with a straight slot are inappropriate for machine guards because they can be removed using improvised tools such as coins and rulers. Fasteners requiring spanners, cross-head screwdrivers or hexagonal (Allen) keys are generally acceptable. Some consultants are making the point that such tools are readily accessible to operatives and maintenance technicians, and these fasteners should therefore not be used for guards. However, this is not what is stated in the European Commission's Guide to application of the Machinery Directive 2006/42/EC and, in several decades' involvement in machine guarding, the author has never been given this advice from the UK health and safety authorities. Indeed, the EC guide states, in relation to Section 1.4.2.1 of the Essential Health and Safety Requirements: "Fixed guards may thus be fixed, for example, by means of bolts, screws or other fasteners that can only be removed by using tools such as keys or wrenches." The EC guide explains the underlying reasoning as: "This requirement aims to restrict the removal of fixed guards to competent or authorised persons." As with all aspects of machinery safety, however, the EC guide emphasises the need for a risk assessment: "The choice of fixing system and tools must be considered in light of the risk assessment."

Captive fasteners

Regarding the need for fixings to remain attached to the guard or machine when the guards are removed, the EC guide states: "The requirement applies to any fixed guards that are liable to be removed by the user with a risk of loss of the fixings, for example, to fixed guards that are liable to be removed during routine cleaning, setting or maintenance operations carried out at the place of use. The requirement does not necessarily apply to fixed guards that are only liable to be removed, for example, when the machinery is completely overhauled, is subject to major repairs or is dismantled for transfer to another site. For the same reason, it may not be necessary to apply the requirement to the casings of machinery intended for use by consumers, where the manufacturer's instructions specify that the repairs requiring removal of these casings are only to be carried out in a specialist repair workshop. In that case, fixing systems should be used that are not easy to remove." As with the issues relating to the use of tools, however, the guide makes it clear that the application of this requirement depends on the manufacturer's risk assessment.

Guards incapable of remaining in place

The requirement for guards to be incapable of remaining in place without fixings is intended to prevent a situation arising in which operatives are unaware that a fixed guard has not been properly fastened or replaced correctly, as such guards might not provide adequate protection when needed.

Guidance and standards

While the EC guide is not legally binding, it is the closest that machine builders have to an authoritative interpretation of the Machinery Directive. At the time of writing, the British Standard corresponding to the appropriate Harmonised Standard is BS EN 953:1997 +A1:2009, Safety of machinery. Guards. General requirements for the design and construction of fixed and movable guards. This will soon be superseded and replaced by an International Standard ISO 14120, the current draft of which contains statements about fixings for fixed guards that are almost identical to those in the EC guide. Once ISO 14120 has been approved and Harmonised to the Machinery Directive as EN ISO 14120, compliance with its requirements will be sufficient for machine builders (and guard manufacturers CE marking guards) to claim that the relevant EHSRs of the Machinery Directive have been met (known as a presumption of conformity).

Definition of 'guard'

So far we have considered the detailed question of fixings for fixed guards but there is sometimes a degree of confusion over what constitutes a 'guard' – for example, it would be easy to adopt the narrow definition from BS EN 953 of a "physical barrier, designed as part of a machine, to provide protection" but to do so would be unwise. A pragmatic approach would be to consider whether hazardous parts of the machinery could be accessed if a component were removed. For this it is necessary to consult EN ISO 13857:2008, Safety of machinery - Safety distances to prevent hazard zones being reached by upper and lower limbs. If the analysis indicates that, say, removing a roof panel would not provide access to hazardous parts, then there is no need to use retained fasteners on that panel or ensure that it cannot remain in place without its fixings. But be aware that EN ISO 13857:2008 only considers hazards associated with reaching over, under, around and through guards; if there are potential hazards from other sources, such as ejected parts or hazardous substances, then those panels will still be classed as guards and will need to be fixed accordingly. In addition, the risk assessment should consider the likelihood of someone extending their reach by standing on a tote bin, chair or other readily available object.

Machine guarding expertise

Procter Machine Guarding is the UK's leading machinery guarding specialist, offering a comprehensive service to survey, design, manufacture and install machine guards nationwide. All guards are designed to comply with EC and HSE requirements and are CE marked or issued with a Declaration of Conformity as appropriate on completion. When necessary, Procter works closely with other suppliers to ensure that interlocking, light curtains and safety-related control systems function correctly in conjunction with the physical guarding. All of this can help machine builders to ensure that guards are cost-effective, ergonomic and standards-compliant so that the complete machine can be CE marked to the Machinery Directive.

To help machine builders and people responsible for the safety of existing machinery, Procter Machine Guarding has published a free White Paper, Fixings for Fixed Guards, which explains the requirements relating to fixings and also provides information to assist designers in selecting fasteners for particular guarding applications. Follow the link to download copies of the White Paper Fixings for Fixed Guards or contact Procter Machine Guarding to request a copy or to discuss specific guarding projects.

04 November 2013

Procter Machine Safetyvisit website
See all stories for this company
 
© Copyright 2006-14 Damte Ltd.