Conformity assessment and damage analysis: competence in practice

2. May 2012

22_Konformitätsbewertungen_Schadenanalyse 1

Damage analyses examine products, their operating conditions, and the requirements and processes relating to them. This raises the question of how damage analyses fit into the conformity assessments described so far. A guideline issued by the Association of German Engineers (VDI), which describes the fundamentals, terminology and procedure for damage analyses, is helpful here. VDI 3822 defines damage as “changes to a product that substantially impair or prevent one or more of its intended functions”.

Steps in a systematic damage analysis

The guideline recommends the following procedure for a damage analysis:

Description of the damage: documenting its appearance, positions and dimensions, recording relevant operating data and, where appropriate, placing the damaged component in the context of the complete functional system in which it is intended to operate.
Taking stock: recording the conditions to which the damaged product was exposed. Recording the component’s history (manufacture, testing, service, etc.), assessing its design and material, and analysing manufacturing and operational use.
Formulating damage hypotheses as a working basis for subsequent investigations, assessing their likelihood and whether they can be substantiated, and involving additional experts for specific questions where necessary.
Performing tests (following an investigation plan, selecting suitable inspection methods and taking appropriate samples) to determine material and service properties, processing-related properties and loads,
Evaluating the test results and analysing whether they confirm conformity with standards and specifications and substantiate the damage hypotheses, and deciding whether steps 2 to 4 need to be reviewed, supplemented or amended,
Identifying and prioritising the causes of damage and the factors contributing to it,
Deriving recommendations for remedial action, which may relate to the materials used, the design, manufacture or operating conditions,
Preparing a report that should include the problem, the investigations performed and their evaluation, the causes of damage and recommendations for preventing damage.

Although VDI guideline 3822 draws on DIN EN ISO 9001 and DIN EN ISO/IEC 17025 as its normative basis, damage analysis goes well beyond simple testing, that is, determining characteristics of an object of conformity assessment using a procedure. The VDI guideline itself classifies damage analysis as expert work.

Damage analysis as “reverse inspection”

Comparing damage analysis with other conformity assessments reveals its close relationship to inspection. It differs from conventional testing primarily in the complexity of the assessment process and in assessment against general requirements, which calls for expert judgement.

A typical question is: “Why did this component fail in service, and how can this be prevented in future?” This is comparable to the question put to an accredited inspection body: “Is this component’s strength sufficient for it to function reliably under typical operating conditions?”

Damage analysis can therefore be interpreted as an “expert reverse inspection” that considers not only the product but also the processes, use and surrounding conditions.