Damage analysis of fiber–metal laminate patches as a repair system for surface defects of steel pipelines

Abstract

In this paper, the failure behavior of fiber–metal laminate patches as a repair system for steel transmission lines has been investigated and the results are compared with those of the other materials commonly used for repairing pipelines such as composite patches. The laboratory test is also employed to experimentally estimate the pipe burst pressure for the tubes made of API A106 Grade B steel. A comparison of the results using different fiber–metal laminates patches and composite is made. As fillers, putties with two different elastic constants are introduced. Also, taking the cohesive behavior of the patch into account in the numerical model, the effect of the patch on the failure pressures is evaluated. The failure parameter in different patch layers for various types of fiber–metal laminates made of GLARE and CARRALL has been investigated. For significant improvement in the failure behavior of fiber–metal laminate patches, carbon fiber layers are used. Also, to prevent corrosion effects between aluminum and carbon fibers, a combination of aluminum, glass fiber reinforced polymer, and carbon fiber reinforced polymer is utilized. Moreover, the damage behavior of steel pipe and aluminum layers in the fiber–metal laminate patch has been numerically described. The results obtained in the present work clearly show the superior advantage of fiber–metal laminate patches over the conventional composite ones. Experimental results lead to the fact that internal pressure corresponding to final layer failure in composite patches and first layer failure in fiber–metal laminate patches should be considered as a reliable estimation to predict the final burst pressure.