The activity of maintenance, through its entire complexity of concepts and actions, ought to assume more than
what is currently understood by the activity of "maintenance and repair". The development of monitoring and
diagnostic techniques of maintenance and their implementation on the process equipment, ensure the lifetime
increase, their safety operation and performance, with positive effects on reliability and productivity. The lack of
a maintenance program or an improper maintenance activity can lead to large-scale disasters, with negative
consequences for humans and for environment [1].