Misapplication of Pressure Vessel Codes in Forensic Applications

Abstract

Engineering codes are a key method to guide designs to safe and reliable outcomes. Many such codes have prescribed calculations where the user provides specific inputs in a series of calculations, often using charts or tables, to get specific outputs. The design margins, units, and underlying theory are not always apparent. Engineering codes may not be suitable for reverse engineering an incident or providing a failure prediction. This article examines a criminal negligence case in which an initial forensic analysis incorrectly applied the ASME Pressure Vessel Code to use Finite Element Analysis (FEA) of a failed pressure vessel section. The flaws in the original analysis were revealed by applying reverse engineering using conventional stress calculations and understanding basic material science. This emphasizes the need to understand the underlying theories with both engineering codes and numerical modeling. Subsequent FEA provided an accurate analysis report that was successfully used in court. These same methods can be applied to many other engineering codes and standards.