Laminations are manufacturing defects that result because of presence of inclusions or air during pipeline plate making. They might present a challenge in identification during ILI inspection as magnetic flux does not identify lamination because it does not have metal loss. Ultrasonic on the other hand can detect lamination, but it does not differentiate from a metal loss.

It is well known in the hot rolled steel making business that nonmetallic inclusions play critical
role in defining steel performance. The objective of this paper is to study laminations that were
detected via Phased Array UT system in X60MS Class-C High Frequency Welded Pipe intended for
offshore application. The linear intermittent laminations appear along the pipe and adjacent to
the weld seam from both sides at a width of 30 to 40 mm with various depths. Technical review
was carried out on 5 available pipes, pertaining to the same heat of the original pipe identified
earlier with lamination, through model experiments; both on the laboratory and on the industrial
scale. At the beginning, depth and distribution of detected laminations were analyzed by manual
UT mapping using normal beam probe. Metallurgical analysis via Energy Dispersive X-ray (EDX)
was carried out on three samples to determine the chemical composition as well as the
morphology of the lamination. The type of inclusion which turned out to be type B (Alumina-
Al2O3) inclusion was identified by evaluating EDX results using Method A per ASTM E45. As it is
a pure material based incident, failure analysis was carried out by the steel maker to identify the
associated root causes from process control prospective and the appropriate preventive
measures to avoid reoccurrence. Eventually, the applied quality control measures during
manufacturing process of HFW pipes, represented in the deployment of UT systems, were
reviewed to identify the reason behind missing such important defect before pipes are being
shipped to the client.