Lamination Defect In Pipe

These fractures are related to the low ductility of a lamination defect when the remaining ligament in the area of the defect reaches general yielding.

Lamination defect in pipe. Many laminations were detected in this pipeline by means of an in line internal inspection tool ili based on transversal magnetic flow tfi. It is a common occurrence where plates are involved for example in the construction of storage tanks. Laminations are sub surface defects that are mostly parallel to the pipe surface 3. Carbon steel plate lamination defect reasons.

Plate lamination defect can be defined as flat and thin subsurface separations present inside metal plate parallel to the surface of the plates. The sources of this defect are inherent discontinuities present in metal such as inclusion and porosity which are flattened during the rolling process. Lamination defect is the most common defect in the manufacturing process of seamless pipe seriously affecting the product quality. It is a type of sheet like internal defect which is mainly caused by the internal cracks bubbles non metallic inclusions in the billet and usually occurs in parallel with the surface of the pipe 1 2.

It is a t ype of sheet like internal defect which is mainly. 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. Lamination is a rolling defect. Laminations air bubbles cavities are one of the common defects in the pipes or shell which may occur during the rolling process of sheets or any other discontinuity in the metals these laminations increase the chances of stress concentrations at such locations which may lead to cause of failure in the form of bursts or leakage such defects in process industries are hazardous hence validations of these defects for their fitness for service is very important.

If the lamination is parallel to the direction of stress and it is in tension then you do not have a major problem. However for large diameter pipes which are made from plates lamination is an issue. The existence of laminations directly reduces the bearing capacity of pipe and may lead to massive explosions. 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.

You can find out lamination by ultrasonic testing.