The evolution of risk identification and risk assessment practices lead to a situation where several methodologies are usually required to go through a complete process from a project management and engineering design point of view.
As well, the evolution of technology and tools, especially in relation with data mining, fuzzy data and model fitting, allows introducing new criteria and considerations in elements of risk assessment methodologies which were formerly determined in a rather simple way.
The paper will define, in first place, the common elements and underlying structure of the methodologies most commonly involved in risk assessment practices: HAZOP, ZHA, FTA, FMEA, Event Tree, LOPA, SIS-SIL. Understanding the application and aim of each methodology allows finding clear relations that help to integrate them in an effective and clear way.
Having a holistic view on the structures and relations of risk assessment methodologies is paramount to define risk assessment practices in a company and define an effective and reliable practices risk assessment. It has many times said that systems should help people to work and not determine the way people work. This is also applicable to risk assessment methodologies.
The paper will also define the principles and conditions that need to be considered to streamline the integration of methodologies. In this sense the boundary conditions of each methodology will be described and the characteristics of the interfaces between them defined.
Finally, considerations will be presented which may lead to risk acceptance by systematically underestimating the risk level. In view of the authors, these considerations should lead to a review of current common criteria and rules applied in some risk assessment methodologies.