Pipeline Lamination Defect

A pressurized pipeline experiences so called hoop stress which creates an environment for axial cracking.

Pipeline lamination defect.

Manufacturing or construction defect lamination cracking dent gouge identified as metal loss other unknown. Lamination defects in base metal mostly parallel to the pipe surface of the pipe. 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. 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 one of the common defects in the manufacturing process of seamless pipes. 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. In this paper the quantitative detection of a lamination defect in thin walled metallic pipe using circumferential lamb waves is studied. Lamination defect in the seam weld.

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. Many miles of pipeline would have to be blocked. Known for example from an inline inspection or as the result of a pipeline. For instance in one case it was found that the defect in its deepest part was curved and broke the outer pipe surface.

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. Lamination defect is modeled by a zero volume crack created using demerging node method. Some of these defects had particular conditions. But pipeline cracks are always detected perpendicular to the main local stress direction of the pipe material.

Another issue is when the material with the lamination is in compression when the lamination lies parallel to the stress direction. The endpoints of the lamination defect are represented by m 101 π. Examples of pipeline defects are shown in figure 2 figure 3 and figure 4. Likewise an axial load on the pipeline supports the occurrence of circumferential cracking.

Only in severe circumstances are they cause for rejection and there are remelting processes that can significantly improve the cleanliness of the metal and reduce inclusions and laminations. The defect type may be.