Risk assessments of machinery

This Part reviews different risk-analysis methods. Risk analysis is a planned activity involving an identification and evaluation of accident risks in the workplace. We will start in Chapter 21 by establishing some common principles of the different risk-analysis methods. We will then in Chapters 22 to 25 go through four different methods that primarily are used in the analysis of the risk of occupational accidents energy analysis, job-safety analysis and comparison analysis. One chapter is dedicated to the risk assessment of machinery. Finally, we will in Chapter 26 review the CRIOP method, where the interaction between the operators and the technical system are analysed when the system is in a disturbed state. The aim is here to prevent major accidents. 

The vendors are responsible for the Risk assessments of machinery. The reports from these assessments are part of the required documentation to issue a declaration of conformity with the machinery regulations. The contractor defines the documentation on risk assessments to be delivered by the vendors for review and verification. This includes the risk assessments for machinery and assemblies of machinery that are critical from a safety point of view (cf. NORSOK S-005 in Norsk Standard, 1999). 

The other relevant main A standard is BS EN 1050 Safety of machinery -Risk assessment, which provides advice on how to carry out a risk assessment on machinery. 

Hani Raafat is a lecturer in Health and Safety at the Department of Chemical Engineering, Aston University. Dr Raafat has produced over 20 publications, and 3 books on reliability, risk assessment and machinery safety. He is a member of the British and European Standards Committees on Fluid Power Machinery Safety, and his main research interests are machinery risk assessment and human reliability analysis. 

Elecric shock as a result of direct contact, means that a person makes contact with part of the circuit which is intended to be live. The only form of protection against direct contact is to prevent such contact in the first place. This can be achieved by following the same principles of risk assessment and machinery safeguarding discussed earlier, namely to provide fixed guards, enclosures or insulation. However, if access is foreseeable, then permit-to-work systems should be operated. It should be remembered that intrinsic safety is an absolute priority in removing the risk of shock injury. This can be achieved by reducing the system voltage in areas of likely contact to such an extent that it cannot result in an electric shock. 

In Norway, the offshore industry has developed guidelines for follow-up of the documentation of machines in project work (NORSOK S-005, see Norsk Standard, 1999). The guidelines are also applicable to land-based industry. We will here present an application of the method and illustrate it with an example from the purchase of a new wire-rolling mill at an aluminium plant. There are also other guidelines on applications of risk assessments to machinery, for example, those developed by the United Kingdom Health and Safety Executive (HSE, 1997b). 

In the Coarse risk assessment, the machinery mannfacturer or the party responsible for the assembly of machinery identifies the main hazards and necessary risk-reducing measures. The purpose is also to identify the need for detailed risk assessments. This activity has to be performed at an early design stage before layout freeze and placement of major purchase orders of subdeliveries. A team similar to the Coarse analysis team is responsible for the analysis, see Chapter 22. The procedure shown in Figure 24.2 is applied and the results are documented in a record sheet according to Table 24.1. 

HSE, 1997b. The Application of Risk Assessment to Machinery. Report SME/484/ 9AI95, Health and Safety Laboratory, Health and Safety Executive, Sheffield. 

The scope of the directive covers the design, manufacture and conformity assessment of pressure equipment and assemblies with a maximum allowable pressure greater than 0,5 bar. A pressure equipment in the sense of the directive is any vessel, piping, safety accessory or pressure accessory. An assembly means several pieces of pressure equipment assembled by a manufacturer to constitute an integrated and functional whole. It is important to be aware that the directive relates exclusively to the pressure risk and that therefore other directives, such as for machinery, low voltage may be applicable to the equipment concerned. 

Safety of machinery—Human physical performance—Part 5 Risk assessment for repetitive handling at high frequency ISO/DIS 11226 1999-02-00 Ergonomics—Evaluation of working postures ISO/DIS 11228-1 1998-08-00... 

For example, the hazard analysis and risk assessment requirements of the European Standard ISO 14121, Safety of Machinery—Principles for risk assessment (formerly EN 1050), have been adequately met in some companies in the design or redesign stages by applying an adaptation of the preliminary hazard analysis technique. 

Safety of Machinery—Principles for risk assessment. International Standard ISO 14121 (formerly EN 1050). Geneva, Switzerland International Organization for Standardization, 1999. 

But EN 292 does not include a methodology to identify hazards and assess risks. To clarity the intent of EN 292 and to provide a framework manufacturers could consider, standard EN1050 was developed and published in 1997. Its title is Safety of machinery—Principles for risk assessment. In 1999, EN 1050 was adopted by the International Committee for Standardization as International Standard ISO 14121, without change. ISO 14121 does what it purports to do It sets forth a hazard identification and risk assessment methodology. 

International Standard ISO 14121 titled Safety of machinery — Principles of risk assessment, 1999. ... 

A workplace hazard identification and risk assessment should be carried out before any modification or introduction of new work methods, materials, processes or machinery. Such assessment should be done in consultation with and involving workers and their representatives, and the safety and health committee, where appropriate. 

In Part 1, one of the provisions is that hazards are to be identified and risks are to be assessed. To assist machinery designers in fulfilling that requirement, a standard known as EN 1050 was written. As stated in the Scope, This International Standard gives guidance on the information required to allow risk assessments to be carried out. In 1999, the ISO issued 14121, which is a verbatim copy of EN 1050. 

Based on this risk assessment, managanent lists and schedules the work needed to be done to create a safe and healthy work environment and eliminate high-risk acts of people. This would mean the introduction of a suitable structured SMS based on world s best practice. All safety management systems should be based on the nature of the business and be risk based, management led, and audit driven. This could include having to guard machinery, demarcate walkways and work areas, purchase correct tools and equipment, and set up maintenance systems for equipment, etc. 

Basic standards (type A). These fundamental standards contain general principles for safe design or measurement techniques/levels for EMC and may be applied to products when appropriate. The A and B standards are especially important for EMC and machinery. Some examples of basic safety standards for machinery are EN 292-1/-2 (Design Concepts), and EN 1050 (Risk Assessment). The EN 61000-4-X series (lEC 801-X) for immunity levels is an example of basic standards for EMC. 

In 2005 and 2006, the risk assessment report was carefully scrutinized and the reasons of occupational accidents discussed in-depth together with management of the company. It was concluded, that the accidents occurred in 2000-2003 were often caused by the lack of safety measures or ignorance of measures by workers while in 2004-2005 the accidents occurred due to the construction principles of certain older machines or worker s inattentiveness of the worker. It is clear, that workers operating with some specific older machine types are easier subjects to work accident and therefore, workers need to be specifically cautious and follow all the safety rules accurately until the company has been able to allocate financial funds to renew the machinery. 

Since no International standard for Mine Hoist exists, this paper reviews the safety management and technical activities, according a selected Safety of machinery standard, in the lifecycle perspective from risk assessment to modification phases during development of a SIL3-capable Hoist protecting system. 

The preliminary risk assessment is made by a risk graph qualitative method described in lEC 61508-5 Annex E according Figure E.l (Figure 3) and Table E.l. This method has been used extensively within the machinery sector, see ISO 14121-2 and Annex A of ISO 13849-1, and enables the safety integrity level to be determined from knowledge of risk factors associated with the hoist machinery and it control system. 

ISO 12100 2010. Safety of machinery—General principles for design—Risk assessment and risk reduction, a type-A (basic) standard. 

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