Corrosion of steels and irons immersed in natural seawater for up to 600 years

CORROSION ◽  
10.5006/3967 ◽  
2021 ◽  
Author(s):  
Robert Melchers
Keyword(s):  
Power Law ◽  
Seawater Temperature ◽  
Bridge Piers ◽  
Natural Seawater ◽  
Outward Diffusion ◽  
Wrought Iron ◽  
Corrosion Loss ◽  
Immersion Corrosion ◽  
Anaerobic Corrosion

Marine immersion corrosion observations for archaeological and other data, including from shipwrecks, wrought iron anchors and cast iron bridge piers are used to estimate corrosion losses in natural unpolluted coastal and near-coastal seawaters for exposures up to about 600 years. Empirical functions for the development of corrosion loss with time were then developed, standardized to 20˚C mean seawater temperature. The resulting slightly non-linear corrosion loss trend, represented by a modified form of the power law, is consistent with Phase 4 of the previously proposed bi-modal corrosion model. These observations support the notion that the rate of long-term corrosion is controlled by outward diffusion, through the rust layers, of gaseous hydrogen generated by the cathodic hydrogen evolution reaction under predominantly anaerobic corrosion conditions. The power-law trend also provides good extrapolation from shorter- term data. For practical purposes for exposures < 100 years in seawaters with mean temperature around 20˚C, a linear model, with longer-term corrosion rate 0.06 mm/y at 20˚C, is sufficiently accurate.

Long-term immersion corrosion of irons and steel in seawaters with calcareous deposition

CORROSION ◽  
10.5006/3685 ◽  
2021 ◽  
Author(s):  
Robert Melchers
Keyword(s):  
Direct Evidence ◽  
Low Permeability ◽  
Microbiological Corrosion ◽  
Wrought Iron ◽  
Corrosion Rates ◽  
Immersion Corrosion ◽  
Moderate Power ◽  
Power Law Function ◽  
Ferrous Carbonate

The marine immersion corrosion of irons and steel under calcareous deposition (principally calcium carbonate) is known to be relatively low for shorter exposures (e.g. a few years). Herein the effect of calcareous deposition on corrosion is considered for exposures up to 1300 years. The data are derived from archaeological steel and iron shipwrecks, cast iron cannons and cannonballs, and wrought iron anchors in locations where there was direct evidence, in and on the corrosion products, of calcareous deposition. Such deposition promotes formation of calcium and ferrous carbonate layers of low permeability on and within rusts. These tend to inhibit both early and long-term corrosion rates. The data show that up to about 200y exposure corrosion losses as a function of time can be approximated closely by a linear function of time. Longer exposures follow a moderate power-law function, consistent with diffusion considerations. Comments are made about the likely interplay between calcareous deposition and microbiological corrosion.

Crevice Corrosion Studies on Corrosion Resistant Alloys in Stagnant Natural Seawater

2012 ◽  
Vol 610-613 ◽  
pp. 276-279
Author(s):  
Laura L. Machuca ◽  
Stuart I. Bailey ◽  
Rolf Gubner
Keyword(s):  
Crevice Corrosion ◽  
Corrosion Potential ◽  
Natural Seawater ◽  
Corrosion Resistant ◽  
Testing Procedures ◽  
Corrosion Studies ◽  
Long Term Performance ◽  
Term Performance ◽  
Positive Effect

Crevice corrosion (CC) was investigated for a number of selected corrosion resistant alloys in natural seawater containing microorganisms for up to 18 months under stagnant conditions. Experimental controls consisted of tests in natural seawater filtered in accordance with hydrostatic testing procedures. The corrosion potential of alloys was monitored throughout exposure and corrosion was evaluated by weight loss and 3D optical microscopy. CC was initiated on several alloys and corrosion rates in time indicated a positive effect of seawater filtration on the long-term performance of the alloys. Microbial adhesion, as indicated by fluorescence microscopy, occurred mainly outside the crevice and differed according to the nature of the substratum surface.

Three Dimensional Numerical Analyses of Bridge Piled-Raft Foundation under Riverbed Erosion

2012 ◽  
Vol 178-181 ◽  
pp. 2373-2377 ◽  
Author(s):  
Wen Tsung Liu ◽  
Yi Yi Li
Keyword(s):  
Bearing Capacity ◽  
Three Dimensional ◽  
Fem Analysis ◽  
Bridge Piers ◽  
Piled Raft Foundation ◽  
River Erosion ◽  
Dimensional Finite Element ◽  
The Face ◽  
Three Dimensional Finite Element

From the 921 earthquake to the major typhoons, including the Morakot typhoon, they damaged original landscape of rivers in Taiwan. In recent years, it alleged that abutment bridge exposed to the most serious security problems. Because of bridge piers in addition to the face of long-term river erosion, the flood on the pier will produce localized erosion near the bridge. The pier will be due to inadequate bearing capacity, resulting in subsidence, displacement, bridge version accompanied by tilting and even caving. The river erosion of soil around the piers deposits and production of contraction will often reduce the bearing capacity. Therefore, how to accurately estimate the scour depth, calculate piers to withstand water impact and analyses its stability for preventing injuries in the first place is the current pressing issues. In this study, three-dimensional finite element method (FEM) analysis program Plaxis 3D foundation is used. Polaris second bridge is selected for analysis. Based on local scouring of the model and various numerical variable conditions, the parameter of bridge pier is studied.

Power-law correlations, related models for long-range dependence and their simulation

2000 ◽  
Vol 37 (04) ◽  
pp. 1104-1109 ◽  
Author(s):  
Tilmann Gneiting
Keyword(s):  
Long Range ◽  
Power Law ◽  
Long Memory ◽  
Stationary Time Series ◽  
Long Range Dependence ◽  
Short Term ◽  
Permissible Range ◽  
Simultaneous Fitting ◽  
Straightforward Proof

Martin and Walker ((1997) J. Appl. Prob. 34, 657–670) proposed the power-law ρ(v) = c|v|-β, |v| ≥ 1, as a correlation model for stationary time series with long-memory dependence. A straightforward proof of their conjecture on the permissible range of c is given, and various other models for long-range dependence are discussed. In particular, the Cauchy family ρ(v) = (1 + |v/c|α)-β/α allows for the simultaneous fitting of both the long-term and short-term correlation structure within a simple analytical model. The note closes with hints at the fast and exact simulation of fractional Gaussian noise and related processes.

scholarly journals On The Critical Phenomena in The Dynamics of Asteroids

1999 ◽  
Vol 172 ◽  
pp. 383-386
Author(s):  
Ivan I. Shevchenko
Keyword(s):  
Phase Space ◽  
Critical Phenomena ◽  
Power Law ◽  
Anomalous Transport ◽  
Selection Effects ◽  
Recurrence Times ◽  
Statistical Selection ◽  
Power Law Decay ◽  
Statistical Effects

AbstractTwo statistical effects in the long-term chaotic asteroidal dynamics are considered, namely the power-law character of the dependence of recurrence times on local Lyapunov times and the power-law decay in the tails of the recurrence distributions. The dependences in both cases are shaped by effects of anomalous transport, due to the presence of the chaos border in phase space, and by statistical selection effects.

scholarly journals Long term immersion in natural seawater of Flax/PLA biocomposite

2014 ◽  
Vol 90 ◽  
pp. 140-148 ◽  
Author(s):  
A. Le Duigou ◽  
A. Bourmaud ◽  
P. Davies ◽  
C. Baley
Keyword(s):  
Natural Seawater
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