Reliability engineering

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Maintenance engineering

For years the risk analysis activities of TECSA S.r.l. have been supported by RAMS type studies for the investigation of issues closely connected with the systems being analysed but not limited to safety aspects Conducting RAMS (Reliability, Availability, Maintainability and Safety) type studies on systems, as well as on subsystems, modules and equipment has several purposes including:

  • setting an availability/objective value;
  • to reveal and correct aspects of design involving a risk that is not tolerable in terms of safety, environment, exposure to operational and economic damage and non-operational economic damage (within the bounds of acceptability defined in the business continuity study);
  • to predict the ability of a system to reach an availability objective value during a particular time frame;
  • evaluating the performance level of a system that is already operational in terms of availability;
  • supporting evaluations of technical and economic opportunities related to alternative solutions of process and design (not exclusively redundancies of components and systems), supplies, operating modes, maintenance modes and spare parts, based on the different impact on the availability of a given system.

Availability is defined as the probability that a system can be functional at a given time. Therefore availability is a function of the number of faults that have occurred in the system in the given time and the time required to restore the system to the functional state after each failure. The reliability of a system is the probability that the system remains functional for a given time. Maintainability of a system is a function of the time required to bring a faulty system to functionality. System availability is, therefore, a function both of reliability and of maintainability.

Tecsa S.r.l. is available to perform full RAMS studies that include:

  • System Functional Block Diagrams (FBD);
  • FMECA analysis (“Failure Mode Effects and Criticality Analysis) of components FMEDA / FMEA , systems and plants;
  • System Reliability Blocks Diagram (RBD);
  • A log of critical equipment and items (tools, parameters, etc.);
  • Equipment and Components MTTF/MTTR list;
  • Equipment and Components Fault Characteristics List;
  • The definition of maintenance requirements, of maintenance policies, of the list of spare parts, etc.
  • Modelling of the degradation of a component over time for the purpose of estimating the availability thereof, considering operating conditions, external and stress events and emergency conditions;
  • Availability modelling of an industrial system (manufacturing, process chemical, mining) also for the purposes of the importance and sensitivity measurement of the equipment involved;
  • Analysis (also with tools for business intelligence and data mining) of field data for the estimation of failure rates and enhancement of “proven in use”;
  • Optimisation of inspections, testing and maintenance;
  • Analysis of criticality and ranking within a complex system;
  • Risk analysis of business interruption in relation to the requirements of a business continuity management system and of a corporate risk management system according to the reference standards (ISO 22313 and ISO 31000).

With regard to the activities of specialist support for maintenance purposes TECSA S.r.l. has created for numerous clients the guidelines for completing the necessary work permits, work permits management practices (within the context of SGS for the Prevention of Relevant Accidents) and has prepared the appropriate forms. This is also to identify any specific needs arising from associated regulatory requirements (e.g. the management of operations in confined spaces, the management of activities of the maintenance of critical elements and systems such as fire apparatus, etc.).

It should be noted that studies relating to verification of availability and reliability are supported by simulation, a field in which  TECSA S.r.l. has become highly specialised over the years; in particular, for RAMS analysis both computational codes that are self-produced with specialised platforms (Mathematica, Matlab, Simulink e Mathematica SystemModeler) and specialised trade computational codes are used, both in the verification of  availability of a system and in the definition of the strategy of maintenance and the management of spare parts that are more appropriate such as Reliass RAMP. These codes allow, given the model of a system or process, rapid verification, often visually, of the behaviour of the same with respect to use cases and different scenarios in order to also highlight the limits in the stress conditions caused by limit situations possibly identified through specific methods (e.g. “What if?” analysis).