A METHOD FOR THE EVALUATION OF THE DIRECT FAILURE CAUSES AND LINES OF DEFENSE OF INSTALLATIONS WITH DANGEROUS SUBSTANCES

摘要

According to the Hazards of Major Accidents Decree, the operator of an establishment should demonstrate in a safety report the risks of an operation and that these risks are adequately reduced. For each installation the most important failure causes should be described together with the effectiveness of the lines of defense installed. For this, a method is developed where in the first step a default is defined for each type of installation together with the default lines of defense related to this installation. A default system is defined as a system containing an inert substance and situated in surroundings not leading to any external causes of failure. The most important failure causes for a default installation are determined using historical data for the different parts of an installation, where also the stage of an installation (design, construction, operation and maintenance) is taken into account. Also a method is used that identifies failure causes based on the process phenomena. After this step it is investigated whether the substances used in the installation or the surroundings of an installation give rise to additional failure causes to be taken into account and subsequent the need for additional lines of defense. Guidelines are given to estimate the effectiveness of additional lines of defense.