‘Mind the gap’ in fitness-for-service assessment procedures-review and summary of a recent workshop

Abstract

'Mind the gap' in Fitness-for-Service (FFS) assessment procedures was a workshop held at The University of Manchester in June 2015. The goal of the workshop was firstly to identify 'knowledge gaps' or areas for improvement in FFS assessment procedures and, secondly, to present methodologies that have been developed to narrow these gaps. It was intended that identification of these 'gaps' would allow an understanding of the current development needs for defect tolerance arguments in the FFS assessment procedures. The following questions were addressed: 1) What are the main 'knowledge gaps' in current FFS assessment procedures and methodologies? 2) What are the main barriers that need to be overcome in order to narrow these 'gaps'? 3) What are the current procedures (if any) and why are these not useful, over-or under-conservative and what needs to be improved? 4) What research is currently ongoing in order to narrow the gaps? This paper summarises the presentations and discussions at the workshop on subjects such as environmentally assisted cracking mechanisms, creep, welding residual stresses and fracture mechanics.

Pit to crack transition and corrosion fatigue lifetime reduction estimations by means of a short crack microstructural model

“…To name a few, BS EN ISO 19902 [10] and DNVGL-RP-C203 [11] are used in Oil and Gas (O&G) and Wind Offshore industries, EN13103 [12], EN13104 [13] or BS EN13261 [14] in the design of axles in railway industry and NUREG/CR-6909 [15] or ASME BPVC Section 3.2 [16] are used for designing in light water nuclear reactor and power generation environments. There remain uncertainty however on the origins of the penalty factors in relation to whether all factors contributing to the damaging mechanism (localised corrosion, pit-to-crack transition and propagation) have been fully considered [17]. Evidence shows that we as a community have not yet addressed corrosion fatigue properly.…”

A review of thermal, microstructural and constitutive modelling of 9Cr steel for power plant applications: Towards a through-process model for structural integrity of welded connections

“…Larrosa et al [14] identified several challenges to accurate assessment of fitness-for-service of pipe components, e.g. development of methods to address load-history effects, definition of reference strain for strain-based methods, the treatment of complicated geometries and loadings, measuring creep-crack initiation times, etc.…”