Pipeline Lamination Defect

Examples of pipeline defects are shown in figure 2 figure 3 and figure 4.

Pipeline lamination defect. Additionally the repair was on a 5 field bend and therefore a type b welded sleeve was not an acceptable repair solution. Lamination defect is modeled by a zero volume crack created using demerging node method. For instance in one case it was found that the defect in its deepest part was curved and broke the outer pipe surface. A major refined products pipeline operator discovered laminations in the seam weld of a 12 pipe.

In this paper the quantitative detection of a lamination defect in thin walled metallic pipe using circumferential lamb waves is studied. Most people hear the words inclusion or lamination and think defect but one should not fear these words and automatically think of defect or rejection. A pressurized pipeline experiences so called hoop stress which creates an environment for axial cracking. Likewise an axial load on the pipeline supports the occurrence of circumferential cracking.

Another issue is when the material with the lamination is in compression when the lamination lies parallel to the stress direction. Lamination defect of a significant area will impair the structural performance of welded objects to the plate surface and may result in a local buckling failure. The endpoints of the lamination defect are represented by m 101 π. The defect type may be.

Inspection method for pipe with lamination defects we have a low temp cs pipeline carrying liquid ammonia at minus 33 deg these pipes were found with lamination defects during construction stage which were later considered to be acceptable after thorough analysis from design view point. Manufacturing or construction defect lamination cracking dent gouge identified as metal loss other unknown. Some of these defects had particular conditions. Many miles of pipeline would have to be blocked.

But pipeline cracks are always detected perpendicular to the main local stress direction of the pipe material. Lamination defect in the seam weld. As shown in figure 3 the lamination defect mn is near the inner surface and parallels to the pipe which divides the pipe into two sub pipes the outer sub pipe and the inner sub pipe. Known for example from an inline inspection or as the result of a pipeline.

Lamination defect is one of the common defects in the manufacturing process of seamless pipes. If the lamination direction is perpendicular to the stress direction in other words the lamination is reducing the load carrying cross section then it is a problem and needs to be sized and most probably removed.