Cryogenic Performance of Adhesively Bonded Metal Joints for LNG Containment System

Abstract

The cryogenic performance of adhesively bonded joints composed of aluminum sandwich structures and stainless steel foils for LNG (Liquefied Natural Gas) containment system was studied. Surface treatment processes such as mechanical treatment, flame treatment, and sulfuric acid etching were applied to the stainless steel foil, whose morphology and chemical composition were determined by SEM (Scanning electron microscopy) and XPS (X-ray photoelectron spectroscopy) with respect to surface treatment methods. Also, the surface free energies of the stainless steel foils were determined with respect to surface treatment conditions. The bond strengths of the single lap joints composed of aluminum sandwich structures and stainless steel foils were measured using modified test specimens at cryogenic temperature with respect to adhesive thickness and repeated thermal shocks, considering real application conditions. Finally, the applicability of metal foil for the barrier tightness of LNG containment systems was validated and an optimum flame treatment condition was suggested for improving the cryogenic performance of adhesively bonded metal joints with thin stainless steel foils.