Under water glued stud bonding fasteners for offshore structures

Abstract

The installation of offshore wind turbines has achieved rapid and substantial progress worldwide and further increase is predicted by enhanced technologies that will reduce costs and increase service time. Secondary structures applied to the primary structure, as the transition piece of a monopole, can be e.g. cable support, boat landing or anode systems. These structures are often welded, which leads to problematic notch effects and hydrogen embrittlement, especially for underwater applications. Also the handling of technical equipment as power current or artificial housings for scuba divers for underwater welding is challenging. Adhesive bonding will lead to cost reduction as the mentioned negative aspects can be avoided. The corrosion protection coating and the primary structure will no longer be damaged and therefore do not need a subsequent coating. This article focuses on the area which is permanently exposed to water. A critical point is how the capability to form adhesion and cohesion, will be influenced by the application process under water. Therefore, stud bonding fasteners are designed that enable the injection of adhesive to the bonding area under water. The load capacities for different adhesives, surface pre-treatments and the degradation by exposure to artificial sea water were investigated. Adhesion was achieved with two different adhesives, which were able to cure and realize reasonable strength under water. Furthermore, two selected coating systems were able to improve the perfor-mance of the adhesive bond.

Nachträgliches klebtechnisches Fügen von Haltern auf bereits beschichtete Stahloberflächen

“…Der Quotient im linken Teil der Gleichung entspricht Gl. (3). Der Sicherheitsfaktor für geklebte Verbindungen für maritime Bauwerke ist in [19] definiert:…”

“…Zu den Herausforderungen zählen insbesondere: Diffusion von Feuchtigkeit in Klebeverbindungen, Verformungs‐ und Abbauverhalten von Klebstoffen und Klebeverbindungen unter Feuchtigkeitseinfluss sowie Korrosion metallischer Substrate. Kürzlich wurde in [3] über das nachträgliche Kleben im Unterwasserbereich mit einem hochfesten, steifen Polyurethan‐Klebstoff berichtet, wobei auch einige Versuche an Epoxidbeschichtungen im atmosphärischen Bereich vorgenommen worden waren. Es wurde insbesondere die Haftfestigkeit des Klebstoffs auf dem Epoxidsubstrat gemessen; systematische Untersuchungen zum Festigkeitsverhalten einer geklebten Gesamtkonfiguration unter atmosphärischen Alterungseinflüssen wurden nicht durchgeführt.…”

Predicting the Macroscopic Shear Strength of Tightened-Bonded Joints from the Intrinsic High-Pressure Properties of Anaerobic Adhesives

“…Regarding marine applications, environmental attacks, due to different factors (i.e., water, temperature), can degrade structural adhesive joints. As reported by Myslick et al, underwater joining by adhesive bonding represents an innovative approach and underwater glued stud bonding fasteners for offshore structures were investigated [6]. Adhesive joints are increasingly being used in shipbuilding, but their application requires better knowledge of their mechanical properties and durability within a hostile environment, such as those faced by ships.…”

Rapid Underwater Adhesive Utilizing Crosslinker and Amine Catalyst-Filled Microcapsules

“…Though rapid underwater adhesives have a wide range of applications from maritime uses to the biomedical field, , few options exist as interstitial water hinders intermolecular interactions between substrates. , Desirable properties for underwater adhesives include high bond strengths, low cure times, and the ability to function on untreated surfaces. , Polyurethanes are excellent candidates for underwater or wet applications because they are not water soluble and retain their high tensile strength when exposed to water for extended periods of time. , Containing both hydrogen bond acceptors and donors (N–H and CO, respectively), polyurethanes have been a popular adhesive as their functional groups allow for intermolecular interactions with numerous substrates . The cure rate of polyurethane adhesives has historically limited their adoption for time-sensitive applications.…”

“…2,5 Polyurethanes are excellent candidates for underwater or wet applications because they are not water soluble and retain their high tensile strength when exposed to water for extended periods of time. 6,7 Containing both hydrogen bond acceptors and donors (N−H and CO, respectively), polyurethanes have been a popular adhesive as their functional groups allow for intermolecular interactions with numerous substrates. 8 The cure rate of polyurethane adhesives has historically limited their adoption for time-sensitive applications.…”