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Predictive aging study – the Apase method

For its own needs, AER has developed a methodology for carrying out predictive aging studies to define equipment’s aging capacities without the need for any experience feedbacks. This methodology has been extended to systems that have not been designed by AER and, as a result, the company carries out aging studies on parts, equipment or systems on behalf of its customers.

To analyze the service life of an item of equipment, a study is made of all the aging phenomena that are liable to occur. These phenomena lead to a deterioration of the equipment and its reliability level drops to a minimum level. The moment this minimum level is crossed defines the limit to the equipment’s service life.

The APASE® method developed by AER enables:

  • aging modes to be identified;
  • their classification to be made in order of importance;
  • their impact to be recognized;
  • ways of reducing this impact to be proposed;
  • a global aging model to be built;
  • help to be given in drawing up a maintenance strategy.


Aging phenomena must be systematically identified on each organ in the system, by considering:

  • the components present;
  • the energy sources present (accumulated during manufacture such as a residual stress, present in design such as kinetic energy in a rotating body);
  • environments;
  • relations between different parts.

The TIPPCE, a tool developed by AER, enables a systematic list to be made of the different modes of interaction liable to be encountered between components, the energies present and the environments.

Every aging mode is studied for determining its severity level and only major aging modes are retained for detailed studies.

A synthesis is then drawn up, in which an iterative redesign process is implemented with a choice of solutions aimed at improving systems’ service life whilst complying with specifications at the same time.