Using calculations analogous to the design calculation, system parts are recalculated with their real geometric dimensions recorded by us. In this way, the service life consumption can be calculated theoretically.

The application of on-site measurements, such as creep strain transducers or additional temperature measurements, can provide valuable information about stress and lifetime of the system. The creep strain measurement, which we apply in particular to weld seams and pipe bends, has often enabled us to predict the service life more precisely and thus continue to operate components with creep damage in a controlled manner. This enables safe and at the same time economical operation of the plants.

Every operator knows the difference between theory and practice. For recording real lifetime consumption of your component, practical in-service inspections in the plant on site are still imperative. These periodic tests include, among other things, examination and evaluation of the microstructure by replica testing. In addition to evaluation of creep stress, this method often allows statements to be made about heat treatment condition of the material, especially in conjunction with mobile hardness testing.
Replica testing is always carried out strictly in line with the specifications of the VGB Standard VGB-S-517 “Guidelines for rating the microstructural composition and creep rupture damage of creep-resistant steel for high-pressure pipelines and boiler components and their weld connections”. This is important to exclude misinterpretations and to obtain a reliable statement about the condition of the component. In addition to replica tests, the inspection for internal flaws by means of ultrasonic inspection is becoming more and more important due to the more flexible operation of many plants. VGB is using both a conventional ultrasonic as well as a new phased-array testing device for such examinations.