Engineering Critical Assessment
Pipeline girth welds often contain “imperfections,” which are alternatively termed “flaws” or “defects.” Traditionally, the tolerable size of those imperfections is set by workmanship-based criteria, such as those in the main body of API Standard 1104. These criteria are empirically-based and historically proven safe in practice. In most cases, they are not quantitatively related to the severity of the defects for the safe operation of the pipelines.
ECA in the context of pipeline girth weld refers to the development of weld imperfection acceptance criteria for the purpose of field girth weld inspection and repair (if needed). The technical basis of ECA is fracture mechanics. When executed correctly, ECA provides a quantifiable level of safety for the project-specific welds and loading conditions. ECA is the preferred method for field girth weld inspection and quality control for long distance pipeline projects.