Corrosion Monitoring of Underwater Steel Structures

Author(s):  
A Birring
2010 ◽  
Vol 163-167 ◽  
pp. 2945-2948
Author(s):  
Li Juan Kong ◽  
Tong Zhang ◽  
Guang Pin Song

Corrosion of steel structures has been found to be a problem Corrosion can be managed but not eliminated, so detecting corrosion will remain an issue no matter how effective corrosion prevention programs become. Electrochemical reaction is the basically process of steel corrosion in civil engineering, so electrochemical method is the best way to monitor corrosion grade. Liquid state reference is often used in lab to study steel corrosion by triple electrode system, but it is very difficultly used in steel bar corrosion monitoring in civil engineering. Firstly, liquid reference’s life is, generally speaking, very short. The steel corrosion is a very slow process, corrosion monitoring should be tens of years, so the liquid reference’s life is not long enough for corrosion monitoring; Secondly, the reference electrode’s strength have to be very high. Obviously, liquid electrode reference can not meet the requirement. In this paper, a novel all solid state reference electrode (ASSRE) has been developed. There are three layers in the electrode. Four kinds of components have been included in first and second layer. Additional AgCl powder has been used to inhibit AgCl decrease which is on the surface of Ag wire by complexing effect. There is only one kind of component in third layer. There are four steps to prepare the reference electrode: electrolyze, pre-mixed components, modelling and sintering. Finally, the potential of ASSR has been measured by SCE.


2008 ◽  
Vol 130 (3) ◽  
Author(s):  
A. P. Shashikala ◽  
J. Ramasubramanian ◽  
G. Janakiraman

The random nature of sea waves and the aggressive corrosive environment of seawater make corrosion an important factor in deciding the safe operational life of offshore steel structures. The consistent rise in offshore oil exploration activities in the last 2 decades has compelled structural engineers and researchers to better understand, the process of corrosion in offshore steel structures. The various electrochemical methods available for corrosion monitoring are polarization, electrochemical impedance spectroscopy and electro chemical noise (ECN) techniques. In offshore industry, the reliable interpretation of electrochemical noise is particularly valuable since it promises new type of online monitoring device. This paper introduces ECN as an online corrosion-monitoring tool for marine structures. The paper discusses the laboratory experiments conducted on test specimens to collect data related to the electrochemical behavior of structural steel such as the polarization data, impedance measurements, electrochemical, potential, and current noise measurements. Investigations were carried out on MS coupons surface prepared and coated with anticorrosive and antifouling paints. An electrochemical workstation capable of collecting data from specimens coated with paint was used for noise data collection. Static corrosion tests have been done and the corrosion rate and corrosion resistance of the coatings were assessed using the statistical analysis. The electrochemical noise data were compared with that of polarization and impedance data and a good correlation between corrosion rates was obtained. The polarization and noise resistance were found to be similar in trend but with variation in numerical values. Statistical parameters like mean, standard deviation, skew, and kurtosis were generated from the obtained noise. These parameters were then processed to obtain noise resistance and corrosion rate. The results were compared with that of polarization and impedance values. The corrosion rate comparison showed a deviation of 10% from polarization with ECN giving the upper bound values. The damage prediction and expected life prediction of a steel jacket platform were also performed using the data collected. The experiments showed a good correlation between the noise resistances obtained from various electrochemical methods. The aim of introducing the ECN as an online monitoring tool for marine structures especially in on-life offshore structures gives valid data with good results and shows good sensitivity.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Siyi Yin ◽  
Haiyan Yang ◽  
Yinghao Dong ◽  
Chengju Qu ◽  
Jinghui Liu ◽  
...  

AbstractPolymer coatings are commonly used to protect carbon steels from corrosion but they are susceptible to weathering and many of them have environmental concerns. Therefore, we studied the possibility of an environmentally favorable inorganic magnesium phosphate cement (MPC) coating for protecting mild steel. A formulation suitable for coating steel was developed by compositional modification [i.e., incremental replacement of dead-burned magnesia (MgO) with magnesium hydroxide (Mg(OH)2)] to a road-repair MPC. This modification yielded an acceptable working time and prevented pore formation at the coating-steel interface. Corrosion monitoring by linear polarization and electrochemical impedance spectroscopy for 14 days found that, the MPC coating substantially increased the linear polarization resistance (Rp) [e.g., day 1: (8.2 ± 1.7) × 103 (nadir value) vs. 495 ± 55 Ω cm−2] and charge transfer resistance (Rct) (e.g., day 1: 9.3 × 103 vs. 3.8 × 102 Ω cm−2). The coated steel underwent neutral sodium chloride (NaCl) salt spray for 2400 h without visible rusting. Immersion for 24 h in liquids simulating the pore fluid indicated that, passivation by the excess MgO in the coating was a major contributor to its anti-corrosive property. Tafel polarization in the liquids found that, corrosion current density (Icorr) followed the rank: 3.5% NaCl solution (6.0 µA cm−2) > 3.5% NaCl solution containing MgO (3.6 µA cm−2) > 3.5% NaCl solution containing fragmented MPC (1.7 µA cm−2), suggesting that a physical barrier effect and dissolved phosphate ions improved its protection. This study shows that, MPC coating is a promising durable and environmentally favorable anti-corrosive material for protecting steel structures in some applications.


1996 ◽  
Vol 8 (1) ◽  
pp. 189-197
Author(s):  
J. Pei ◽  
M. I. Yousuf ◽  
F. L. Degertekin ◽  
B. V. Honein ◽  
B. T. Khuri-Yakub

TAPPI Journal ◽  
2016 ◽  
Vol 15 (7) ◽  
pp. 467-477
Author(s):  
PASI NIEMELAINEN ◽  
MARTTI PULLIAINEN ◽  
JARMO KAHALA ◽  
SAMPO LUUKKAINEN

Black liquor high solids (about 80%) concentrators have often been found to suffer from aggressive corrosion. In particular, the first and second effect bodies are susceptible to corrosion attacks resulting in tube leaks and wall thinning, which limit the availability and lifetime of evaporator lines. Corrosion dynamics and construction materials have been studied extensively within the pulp and paper industry to understand the corrosion process. However, it has been challenging to identify root causes for corrosion, which has limited proactive measures to minimize corrosion damage. Corrosion of the first phase concentrator was studied by defining the potential regions for passive area, stress corrosion cracking, pitting corrosion, and general corrosion. This was achieved by using a technique called polarization scan that reveals ranges for the passive area in which the equipment is naturally protected against corrosion. The open circuit potential, also known as corrosion potential, and linear polarization resistance of the metal were monitored online, which allowed for definition of corrosion risks for stainless steel 304L and duplex stainless steels 2205 and SAF 2906. An online temperature measurement added insight to the analysis. A process diagnostics tool was used to identify root causes of the corrosion attacks. Many of the root causes were related to process conditions triggering corrosion. Once the metal surface was activated, it was difficult to repassivate the metal naturally unless a sufficient potential range was reached.


The choice of cost-effective method of anticorrosive protection of steel structures is an urgent and time consuming task, considering the significant number of protection ways, differing from each other in the complex of technological, physical, chemical and economic characteristics. To reduce the complexity of solving this problem, the author proposes a computational tool that can be considered as a subsystem of computer-aided design and used at the stage of variant and detailed design of steel structures. As a criterion of the effectiveness of the anti-corrosion protection method, the cost of the protective coating during the service life is accepted. The analysis of existing methods of steel protection against corrosion is performed, the possibility of their use for the protection of the most common steel structures is established, as well as the estimated period of effective operation of the coating. The developed computational tool makes it possible to choose the best method of protection of steel structures against corrosion, taking into account the operating conditions of the protected structure and the possibility of using a protective coating.


2016 ◽  
Vol 12 (1) ◽  
pp. 28-35
Author(s):  
H.M. Nykyforchyn ◽  
◽  
V.A. Chervatyuk ◽  
V.I. Marukha ◽  
Z.V. Slobodyan ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document