Welding-induced residual stress distributions are required as a priori in performing fracture mechanics based fitness-for-service (FFS) assessment of structures that contain welded components. Unfortunately, residuals stress prescriptions in current Codes and Standards are not only very limited and overly conservative, but are highly inconsistent from one Code to another. Nearly all FFS procedures in current Codes and Standards fail to consider how to properly treat residual stresses from welding operations in fracture mechanics parameter calculations, resulting in a gross over-estimation of residuals stress effects on structural integrity. To obtain a reasonable residual stress estimate, the required computational and experimental analysis procedures can be viewed as cost-prohibitive for use in performing day-to-day FFS assessments.

OUR APPROACH

Over the past several decades, Battelle has developed a suite of unique, highly advanced computational simulation tools.  These tools have been used to develop comprehensive residual stress distributions for FFS applications for many joint geometries (see the illustration at the right) and component types that have been validated against a large amount of detailed measurement data.  With the comprehensive knowledge base on residual stresses, a unified residual stress description has been developed by capturing the most critical parameters that govern the through-thickness residual stress distributions for FFS purposes.

Battelle’s unified residual stress description for pressure vessel and piping components has been adopted by the new API 579/ASME FFS-1 which issued in 2007.