Single Lap Joint Testing With Analytical and FEM Verification for Pipe-in-Pipe Application

In the Pipe-in-pipe (PIP) system, stress transfer takes place through the annular space, so that the material used as insulator in the annular space should posses good bonding strength to keep both pipes in position during installation in deep-water. One way to quantify this bonding shear strength is by the single lap shear tests. In this study, the effect of coarse aggregates [<19.1 mm (0.752 inch)], sand [<5 mm (0.2 inch)] and microspheres [<0.2 mm (0.008 inch)] on the bonding shear strength of a polyurethane based polymer grout was investigated. The shear bonding strength between the grout material and steel was determined using the single lap configuration. The maximum bonding shear strength of polymer-aggregate and polymer-sand composite were 1.8 MPa (260 psi) and 2 MPa (285 psi) respectively, with 60% of fillers (by weight) in the polymer composite. Addition of aggregate and sand improved the bonding strength. A finite element analysis was used to investigate the parameters that influence the shear stress distribution in the test configuration and the results were compared to the Volkersen's analytical solution. Effect of modulus, lap length and lap thickness on the shear stress distribution was investigated.