Experimental and numerical determination of critical osmotic blister size affecting the strength of aged FRP seawater pipe

Abstract

Glass fiber-reinforced polymer (GFRP) composite pipelines are used by many industries for fluids transport including seawater for cooling. The durability of these pipes can be affected where the loss of their strength is due to the occurrence of several internal irreversible micro-damages. One of the challenges facing the integrity of these pipelines is the presence of surface defects. The present research aims to determine the critical size of osmotic blister affecting a 30- year-old seawater handling GFRP pipe. Osmotic blisters were simulated through surface notches with two different geometries and sizes. Longitudinal pipe mechanical strength was studied through tensile tests to study the effect of the surface notch size. At a certain surface notch depth, the strength of the pipe wall decreased with increasing the notch surface depth. This represents the critical value of the damage size called maximum undamaged defect size and noted d max. Damage with size below d max does not affect the strength of the pipe wall. To simulate the progressive failure of this aged composite, a 3-D finite element model was employed based on Hashin’s failure criteria.

Investigation on the Durability of E-Glass/Epoxy Composite Exposed to Seawater at Elevated Temperature

“…The durability of the structures also affected by the presence of defects on the surface of the polymer matrix composite before immersion. It can be regulated by determining the effect of the critical size of the osmotic blister [ 25 ]. Furthermore, the strength of the structure can be improved by repairing the structures with glass fiber-reinforced polymer [ 26 , 27 ].…”

Laboratory tests and analysis of CIPP epoxy-resin internal liners used in pipelines – part I: comparison of tests and engineering calculations

“…One of the similar material is glass fibrereinforced polymer (GFRP) composite, which is used by many industries. The subject of the research and simulations were, for example, damage such as osmotic blisters [1]. Under investigation were also failure analysis of cracked steel pipe repaired by GFRP.…”