Creep Assessment

Surface replication and microstructural studies are extensively used to detect creep cavitation and carbide morphology in service components These techniques are capable of providing early warning of creep exhaustion in high temperature components, well in advance of that achievable by conventional NDE methods.

Quantification of damage e.g. creep cavitation (Cane & Shammas, 1984, and Eggeler, 1991) and carbide morphology (Masuyama, 1993), has led to the increased confidence in the prediction of life fraction by these methods.

In boiler headers and steam pipes, creep is a major cause of cracking, with damage most likely to appear in localised brittle regions, such as those near welds.
Usually, the first sign of creep damage is the formation of microscopic cavities at grain boundaries of the heat-affected zone near a weld, which eventually coalesce and expand into cracks.

The evolution of such creep cavitation can be used to provide an estimate of service life already expended and of the actions required to prevent failure. Metserve field team has been involved with creep evaluation at many power station locally and abroad.