Loading...
3 results
Search Results
Now showing 1 - 3 of 3
- Establishment of optimal physical assets inspection frequency based on risk principlesPublication . Sobral, José; Ferreira, LuísRisk Based Inspection (RBI) is a risk methodology used as the basis for prioritizing and managing the efforts for an inspection program allowing the allocation of resources to provide a higher level of coverage on physical assets with higher risk. The main goal of RBI is to increase equipment availability while improving or maintaining the accepted level of risk. This paper presents the concept of risk, risk analysis and RBI methodology and shows an approach to determine the optimal inspection frequency for physical assets based on the potential risk and mainly on the quantification of the probability of failure. It makes use of some assumptions in a structured decision making process. The proposed methodology allows an optimization of inspection intervals deciding when the first inspection must be performed as well as the subsequent intervals of inspection. A demonstrative example is also presented to illustrate the application of the proposed methodology.
- Maintenance of fire sprinkler systems based on the dynamic assessment of its conditionPublication . Sobral, José; Ferreira, LuísSafety is one of the major concerns of process safety engineers in most industrial facilities all over the world. To this scope, some events play an important role once the effect of their consequences can be assumed as totally undesirable. One of these events refers to the occurrence of a fire. Such event can result in catastrophic consequences for life, equipment, and continuity of activities or even leading to environmental damage. A fire protection equipment with low reliability means that this equipment are often unavailable and thus the risk of a fire increases. Maintenance of fire protection equipment is very important because this kind of systems is mostly in a dormant mode, which gives uncertainty about their operability when demanded in a real situation of fire. This article outlines the importance of tests, inspection, and maintenance operations in the context of a fire sprinkler system and proposes a methodology based on international standards and supported by test/inspection reports to correct the frequency of these actions according to the level of degradation of the components and regarding safety purposes. © 2015 American Institute of Chemical Engineers.
- Establishment of an initial maintenance program for UAVs based on reliability principlesPublication . Gonçalves, Paula; Sobral, José; Ferreira, LuísPurpose - The purpose of this paper is to illustrate how to develop a methodology to set up an initial maintenance program for unmanned aerial vehicles (UAVs) following the well-known Steering Maintenance Group logic method (MSG-3) and taking into account safety concerns based on items probabilities of failure. That is why it is stated that maintenance program is based on reliability principles. Design/methodology/approach - The proposed methodology follows the MSG-3 framework applied to civil aircraft but where the determination of each probability of failure is achieved applying a morphological analysis. These probabilities are then affected by some factors to calculate the adjusted values to the specific conditions (design, operation and environment) under which the system is expected to operate. Findings - Main findings are related to the applicability of the morphological analysis on the developing of an initial maintenance program when there is a lack of data that disable the establishment of a coherent maintenance program. Research limitations/implications - Limitations are related to the absence of a legislative framework consensual in Europe for certification of UAVs and the lack of data concerning UAVs failure modes, causes and their probability of failure. Practical implications - The developed work and the methodology proposed may be useful for UAVs maintenance program engineers and technicians when developing new systems. Originality/value - The originality is based on the use of morphological analysis for UAVs to determine the items probabilities of failure when there is a no-data problem. Based on the referred analysis, it is possible to create an initial maintenance program for UAVs.