Tanks criticality assessment by the dependability method. Case study

• A dependability approach is applied to a “concrete tank” system in terms of functions to be fulfilled.
• The FMECA method considers systematically and successively each component of the tank and its failure modes analysis.
• These failure modes have been quantified according to different parameters, and prioritized by a causal graph.
• Finally it evaluates the criticality of the failure of each function component and the overall criticality of the tank.
• As case study, we illustrate the method in a water storage tank, placed on the ground, of a 2000 m3 capacity, in Algeria.

In industry, performing dependability evaluation along with other analyses allows anticipating and making trade-offs. This field has then gained its current distinguished standing, mainly during the last half-century, in areas such as defense, aeronautics, space, and nuclear. It is now absolutely crucial and critical for all sectors of industry, particularly in civil engineering. However, dependability is able to include, explicitly, the failures, uncertainties, hazards, etc. as far as their corresponding knowledge. It also highlights the absence of the dependability process as the awareness of the studied system does not exist. With this approach, “concrete tank” system study has been conducted in terms of functions to be fulfilled and designed to understand the way it works. The FMECA (Failure Modes their Effects and Criticality Analysis) method, to be discussed in the present work, consider systematically and successively each component of the tank and its failure modes analysis. Furthermore, a failure mode corresponds to the state in which the considered tank will not fulfill its major function: each unachieved, or badly achieved, function is matched up into a given a failure mode. These failure modes have been quantified according to different parameters, and prioritized by a causal graph. Finally this method will evaluate the criticality of the failure of each function component before proceeding to the evaluation of the overall criticality of the tank failure.As a practical application (case study), we illustrate the method of dependability in a water storage tank, placed on the ground of a 2000 m3 capacity and located in a coastal town in Algeria, in order to be investigated. This structure, we studied here, was built in 1987 and has been then examined and analyzed 20 years later.