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NIST SP 951
Risk AssessmentMost New Approach Directives require a risk evaluation of the products they govern. Assessing risks in the design phase of a product is an established practice. A good designer examines all possible risks related to a design, and does everything possible to remove them. A designer must be able to (legally) defend the safety aspects of his design decisions for a period of at least ten years (five years for medical devices) after placing the product on the European Union market. A systematic risk assessment on the one hand, and good documentation of the design decisions concerning safety on the other, are essential components of a viable legal defense. A systematic risk assessment also forms the basis of self-certification and is the essence of the Technical File. Two Harmonized Standards have been developed to assist the manufacturer in the risk assessment of Machinery (EN 1050) and Medical Devices (EN 1441).
A good example is found in Annex I of the Machinery Directive titled "Essential Health and Safety Requirements Relating to the Design and Construction of Machinery." This Annex provides both a description of a safety-conscious design approach, and a list of desirable safety characteristics. The principles elucidated are sound principles that, when followed, will substantially support a legally defensible design. The list of safety characteristics is a reasonably thorough list that facilitates the critical design review process. This design review is often referred to as a Risk Assessment. By using the contents of Annex I, a manufacturer is more likely to prepare a complete Risk Assessment. The self-declaring manufacturer is required to list the Essential Health and Safety Characteristics of the Machinery Directive (these are contained in Annex I), and describe the measures taken to minimize the hazards that are described therein. Basically, this aspect of the directive describes an obligation to engage in a critical design review, focused on product safety, with the results documented in writing. This is the step that many manufacturers have not undertaken, prior to exporting to the European Union. The precise form of this exercise is left to the discretion of the manufacturer, and may be in the form of a Failure Modes and Effects Analysis, or a HAZOP (Hazard of Operations) analysis, or some other form that serves to direct the safety related aspects of designing a safe machine, and teaching people how to use it safely. Return to the Table of Contents
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Some manufacturers approach risk assessment by using a design standard. Conformity to a standard, however, does not necessarily mean that the manufacturer will escape liability for a faulty design. Conformity to a standard may only provide a rebuttable presumption of conformity with the safety requirements of the directive. The strongest defense against liability is the combination of the use of standards where reasonable, and a documented design review that shows how the manufacturer effectively minimized risk.
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