Corrosion of steel piling in seawater harbours

Abstract

2Unexpectedly high levels of corrosion of sheet and other steel piling were observed in UK harbours during the 1980s, and a phenomenon termed 'accelerated low water corrosion' (ALWC) caused considerable concern about the structural safety of harbour quays and facilities. This paper shows that the severity of corrosion of steel piling both in the tidal zone and in the immersion zone is correlated with the concentration of dissolved inorganic nitrogen (DIN) in the local seawater. In the lower tidal zone this is consistent with the thinning of piles associated with ALWC. Previously it has been shown that in the horizontal direction the ALWC phenomenon is associated with material variability. Models are developed to allow the prediction of expected average corrosion loss both in the immersion zone and for the lower tidal zone (the ALWC effect) as a function of DIN, water temperature and exposure period. Data are presented to show the relatively low beneficial effect of changes in steel composition. It is concluded that for long-term protection against corrosion reliance must be placed on protective and preventive measures. NotationA corrosion loss in ALWC zone c s corrosion loss at time t a c s long-term corrosion loss parameter I mean corrosion loss in the immersion zone N annual mean dissolved inorganic nitrogen concentration P mean corrosion loss in the immersion zone in nutrient polluted waters R A ratio of corrosion loss in ALWC zone compared with corrosion loss in immersion zone 5 A / I R P ratio of corrosion loss in ALWC zone compared with corrosion loss in immersion zone for nutrient polluted waters 5 A / P r s corrosion rate T annual mean water temperature t time (years) t a time for transition from phase 2 to phase 3 t e net exposure period 5 actual exposure period -life of protective coating or cathodic protection

Long-term corrosion of abandoned offshore steel infrastructure

“…Estimates for the relationship between DIN and marine immersion corrosion including the effect of MIC are available [45]. Estimates also are available for marine corrosion losses in the tidal and the near-surface zones(so-called Accelerated Low Water Corrosion -ALWC) [50][51][52].…”

Profiling Corrosion Rates for Offshore Wind Turbines with Depth in the North Sea

“…Accelerated low water Energies 2020, 13, 2518 4 of 19 corrosion (ALWC) is usually experienced in those waters which is an aggressive form of microbial influenced corrosion (MIC) that may occur on steel in estuarine and marine structures [19,20]. ALWC has been observed to be enhanced with dissolved inorganic nitrogen (DIN) [21]. In general, coupons are suspended from fixed structure or the piles are removed after a number of years of service to capture the corrosion rate.…”