Abstract
Recent studies show that rigid, closed cell polymer foam blocks seawater penetration and provides corrosion protection to the internal surfaces of metal cavities exposed to aqueous salt environments. The present study explored properties of rigid polyurethane foam that would impact its durability and effectiveness as an agent for corrosion protection. In particular, the bonding strength and cure morphology of polyurethane foam prepared from single-part injectable and two-part pourable formulations applied to steel tubular structures were investigated. Water absorption and retention characteristics of the cured foam also are presented. Tests showed that upon curing, the foam provided excellent coverage and adhered well to as-manufactured and precorroded metal surfaces. For the one-part formulation, no significant water was retained after 8 weeks of total seawater immersion. In the same test, the greatest amount of moisture retained by the cured foam from the two-part formulation was ∼ 1 vol%. Results suggested that within a confined metal cavity, rigid polyurethane foam acts as a well-sealed barrier coating or as an entry plug to block the intrusion of detrimental solid or corrosive fluid material. Two distinct advantages to using self-expanding, rigid polyurethane foam for retrofit corrosion control are its excellent adherence to precorroded metal surfaces and convenient application by remote injection to regions that are difficult or impossible to access for surface preparation and the application of protective paints.
