The use of composite to eliminate the effect of welding on the bending behavior of metallic pipes

In this study, the fiber-reinforced polymeric composite (FRP) overwrap system is proposed to eliminate the effect of the heat-affected zone on the pressure capacity and the deterioration property of the welded pipes. The proposed FRP overwrap system has many advantages. It is cost-effective, and it eliminates the external corrosion while increasing the pressure capacity of the welded pipes. In addition, it also prevents the unplanned shutdown of the pipelines. To evaluate the effectiveness of the proposed FRP overwrapped system, firstly, steel pipe specimens with welded regions were prepared. Secondly, the welded regions were overwrapped with composite material (glass fiber and epoxy resin) using filament winding machine. Finally, the fabricated specimens were tested using three-point and four-point bending tests using the Instron machine. All failure modes of the tested specimens were observed and analyzed using the scanning electron microscopy (SEM). It was proved that the use of the proposed FRP overwrap system had eliminated the effect of the heat-affected zone in welded/steel pipes. The results of three bending tests showed that the maximum flexural load for pipes with two and four welding lines has increased by 16.94 kN and 10.35 kN, respectively. On the other hand, for a four-point bending test, the maximum flexural load has increased by 26.8 kN.