Development of methodology for the inspection of welds in lined pipes using array ultrasonic techniques

In recent years, the need for new technologies in the oil and gas industry has increased substantially due to the discovery of new oil and gas fields that are hard to access. One specific concern in this industry is the need to increase the reliability of mechanically-lined pipes employed offshore. This kind of pipeline contains a complex girth weld joint, which experiences fatigue during its operation and plastic deformation during its assembly and deployment, ie reeling and unreeling. This paper presents the early-stage development of a non-destructive inspection technique aiming to assess flaws in lined pipe joints. The proposed technique utilises a finite element model to apply the time reversal principle in the total focusing method. This preliminary stage will be conducted by computational modelling and experimental testing in an Alloy 182 dissimilar weld block, which mimics some aspects of lined pipe girth welds. Previous studies of the same sample investigated its metallurgical structure and grain texture, allowing the inherent anisotropic and inhomogeneity effects of such coarse-grained material to be accounted for. The present analysis is expected to provide useful insight into the liner-weld overlay interface inspection problem.