Shear Bonding and Thermal Properties of Particle-Filled Polymer Grout for Pipe-in-Pipe Application

Pipe-in-Pipe (PIP) configurations are considered as a practical solution to deepwater oil production to prevent hydrate formation and paraffin deposition during the transportation of crude oil to production facilities. The optimal design of a PIP configuration requires a balance between the structural performance and the thermal insulation of the grout material used to fill the annular space. In this study, the effect of aggregates $(4–19.1\mathrm{mm})$ , sand $(0.4–5\mathrm{mm})$ , and microspheres $(<0.2\mathrm{mm})$ on the bonding shear strength and thermal conductivity of a polyurethane-based polymer grout was investigated. The shear bonding strength between grout material and steel was determined using single-lap configuration. Addition of aggregate and sand improved the bonding strength. Hot wire method was used to determine the transient thermal conductivity $\left(k\right)$ of polymer-based insulator with and without filler materials. The average maximum bonding shear strength of polymer–aggregate and polymer–sand composite was $1.79\mathrm{MPa}$ $\left(260\mathrm{psi}\right)$ and $1.97\mathrm{MPa}$ $\left(285\mathrm{psi}\right)$ , respectively, with 60% of fillers (by weight) in the polymer composite. The average transient thermal conductivity of polymer was $0.091\mathrm{W}∕\mathrm{mK}$ , which was reduced due to the addition of microspheres and increased due to the addition of aggregates and sand. Based on published data a relationship between thermal conductivity and density was developed and verified with data from the current study. Also, relationships between thermal conductivity, pulse velocity, and bonding shear strength were developed using the test data.