Conducting HAZOPs in continuous chemical processes: Part I. Criteria, tools and guidelines for selecting nodes

The aim of the present paper is to provide new tools and criteria for conducting HAZOPs in continuous chemical processes (e.g., petroleum-refining processes). These are mainly based on five HAZOPs of different systems, conducted by different teams. Its scope covers the organizational step of the HAZOP study, which principally entails selecting the nodes to be analyzed and estimating the time required to examine them. These two aspects are focused on defining and planning the sessions that will be necessary to complete a HAZOP study. Part I of this paper focuses on developing tools, guidelines, and criteria for selecting and sizing nodes. A methodology for selecting nodes is illustrated and mathematical models for predicting the number of nodes to be selected and the time needed to select each node are presented. Part II focuses on developing a HAZOP time estimation model for predicting the time required to perform the whole HAZOP, from its preparation and organization up to the release of the first HAZOP draft report.

► The present paper provides tools and criteria for conducting HAZard & Operability studies (HAZOPs) in complex continuous chemical processes.
► We offer guidance on how to select nodes, and which node size is the optimum one for HAZOP brainstorming.
► We propose a Node Selection Methodology (NSM).
► A simple model was developed for predicting the number of nodes to be selected according to the process size and complexity.