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Bis(2-ethylhexyl) phosphate (BEHP) was exposed to carbon steel surfaces from dry and water-saturated dodecane. The resulting changes to the surfaces were characterised using spectroscopic techniques (energy dispersive X-ray (EDX), X-ray photoelectron (XPS), and far-infrared reflection absorption (RAIRS) spectroscopies) and polarised neutron reflectometry (PNR). Although there was no observable affinity of BEHP to the steel surface in dry solvent, a layer of rough iron (III) phosphate formed in water-saturated dodecane. The phosphate-reacted steel surface showed some resistance to corrosion by seawater, suggesting the formation of a cohesive barrier against corrosive species. The results support the use of BEHP as an anti-corrosion additive and a viable phosphating agent for steel surfaces.

This work investigates the corrosion of offshore structural steel surfaces over particularly short timescales. The focus is on the short-term effects between surface treatment and coating application (typically several hours). Offshore structures are exposed to an aggressive marine environment, where substrates will be contaminated by aerosols containing salts within hours, even under mild weather conditions. Localised corrosion studies of the anodic and cathodic regions of S355 steel surfaces undergoing salt drop corrosion are characterised. Significantly, the corrosion products are found to grow rapidly and are inhomogeneous, porous, and amorphous. They evolve to higher oxidation state oxides quickly with corrosion time. Therefore, microscopic corrosion products will form on newly exposed substrates in marine environments, even before the protective paint is applied.