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PublisherNACE InternationalLanguageEnglish
Document ID 00070757
Content TypeJournal Paper
TitleProperties of Rigid Polyurethane Foams Related to Their Use for Corrosion Control Inside Confined Spaces
AuthorsP.P. Trzaskoma-Paulette, S.G. Lambrakos, and H.N. Jones
JournalCorrosion
VolumeVolume 56, Number 07
DateJuly, 2000
Copyright2000. NACE International.
Keywordscavities, polymer foams, polyurethane foams, seawater, steel corrosion
PreviewABSTRACT
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.

The use of rigid, closed cell polyurethane foams as a method to inhibit corrosion of the interior surfaces of metal structural cavities exposed to seawater and moisture recently has been investigated.1-5 Unfilled metal cavities are a general feature of various structures or parts used in the building, automotive, heavy equipment, marine, and aerospace communities. Premature deterioration of the internal surfaces of these cavities is associated with the fact that they usually are poorly protected from corrosion and provide a region for the accumulation and stagnation of salt-laden debris and moisture during exposure to marine environments. Application of protective paints during parts manufacturing often is prohibited because welding or other joining operations could damage or destroy preexisting coatings. Postmanufactured protective treatment often is inconvenient or impossible because cavities are difficult to access for surface preparation and paint application. Remotely applied self-expanding polymer foams offer a possible solution to the protection of internal cavity surfaces either on a temporary or long-term basis. Rigid polymer foams have been used for insulation in the building industry for recreational boat hulls, flotation devices, and crack and void fillers in various maritime, automotive, and aircraft structures.6-7 While this methodology experiences wide
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