HRL uses well proven methodologies to assess the residual life of materials from knowledge of creep properties, degradation processes, material condition, thermal history and operating stress.
For more precise prediction on critical components, accelerated creep tests can be carried out either on miniature samples removed non-destructively from the operating component, or on full size samples.
HRL has been involved in life assessment investigations and research studies for over thirty years. Techniques for assessing life degradation have been developed and evaluated in laboratory test programs. This has established the reliability of microstructural changes, carbide transition and development of cavitation as an indicator of the creep condition of various alloy steels. Creep testing techniques utilising miniature samples (that can be taken from operating plant non-intrusively) tested under argon have greatly improved the reliability of assessments.
Plant studies have been carried out involving the detailed collection and analysis of data on the thermal histories of components, and various data reduction methodologies have been developed to assist in the process. Plant instrumentation and other indirect techniques such as using the measured bore oxide thickness have also been used to understand the thermal history and thus determine the remaining life of creep-damaged materials. Studies into the creep behavior of weldments, and the weld repair of creep damaged steels are also keeping our engineers at the forefront of knowledge of creep and life assessment.