Stochastic modelling of corroded surface features of structural steel under sulfate attack

CORROSION ◽  
10.5006/3842 ◽  
2021 ◽  
Author(s):  
Youde Wang ◽  
Xiaodong Zhou ◽  
Shanhua Xu
Keyword(s):  
Structural Steel ◽  
Steel Structures ◽  
Stochastic Modelling ◽  
Corrosion Damage ◽  
Sulfate Attack ◽  
General Corrosion ◽  
Accelerated Corrosion ◽  
Corrosion Depth ◽  
Average Value ◽  
Pit Depth

Steel structures exposed to the sulfate corrosive environment for a long time will inevitably suffer random corrosion damage, which will lead to uncertain degradation in the mechanical properties of materials and structures. The safety and reliability assessments of corroded steel structures largely depend on the quantification of corrosion characteristics. In order to investigate the corrosion features of structural steel under sulfate attack, six batches of accelerated corrosion experiments were conducted on 18 steel specimens. The surface morphologies of all corroded coupons were firstly measured by a 3D surface profilometer, and then the surface parameters were calculated/extracted and analyzed by a self-written analysis algorithm to clarify the distribution characteristics and evolution laws of corrosion depth, pit depth and pit shape. The results revealed that the corrosion form of structural steel under sulfate attack was a rather uneven general corrosion, which exhibited the intersection of general corrosion and pits. The corrosion depth obeyed a normal distribution, and its average value, standard deviation, and the power spectrum peak increased as the corrosion age increased. The depth and aspect ratio of corrosion pits were both in accord with the lognormal distribution and showed the increasing and decreasing trend with the corrosion time going on, respectively. Besides, the probabilities of different pit shapes in different depth ranges were obtained, in which cone pits accounted for the largest proportion, and the pits gradually changed from cylindrical and hemispherical to conical with the increase of pit depth. In the end, the random models for corrosion depth and pits were established based on the statistical results, which realized the reconstruction and random modelling of corrosion characteristics of structural steel under sulfate attack.

Reliability-based minimal sample factor formulation for a corrosion damage assessment in aluminium alloy plates

2005 ◽  
Vol 40 (8) ◽  
pp. 801-816 ◽  
Author(s):  
J. J Xiong ◽  
R. A Shenoi ◽  
H. Y Qiu
Keyword(s):  
Aluminium Alloy ◽  
Power Law ◽  
Corrosion Damage ◽  
Accelerated Corrosion ◽  
Corrosion Depth ◽  
Minimal Sample ◽  
Atmospheric Exposure ◽  
Power Law Function ◽  
Pit Depth ◽  
Corrosion Time

Accelerated corrosion tests and atmospheric exposure tests are conducted to investigate the corrosion performance of LY12CZ aluminium alloy. Based on the experimental data, the corrosion depth at different corrosion times is determined using a fuzzy discrimination method which follows a log-Gauss distribution. From the experimental observations, the minimal sample factor formulation and a power law function model with three parameters are presented to assess safe corrosion damage at different corrosion times and to describe the corrosion depth law with corrosion time. From the application examples of this model, it is shown that the data for corrosion depth are better defined by a three-parameter power law function shown in the figure. Statistical analysis shows a strong correlation between pit depth and observed corrosion time. Finally, the equivalent relationship between accelerated corrosion and atmospheric exposure corrosion is established.

scholarly journals Research of Supporting Ability and Prediction of Residual Life of Casing Pipes at General Corrosion Damage of Inner Surface

2021 ◽  
Vol 225 ◽  
pp. 02002
Author(s):  
Natalia Fedorova ◽  
Yulianna Dimitriadi ◽  
Nikita Ryapolov
Keyword(s):  
Residual Life ◽  
Corrosion Damage ◽  
General Corrosion ◽  
Corrosion Depth ◽  
Inner Pressure ◽  
Nominal Thickness ◽  
Inner Surface ◽  
To Receive

The detection and the measuring of the developing damages must be accompanied by evaluation of the supporting ability of the design in terms of the increasing size of a defect. If the type of damage is dominant one on the further period of the operation, so the received functional dependences can be used to predict a residual life of the designs. As illustrated by the casing pipes of 168.3 mm diameter, where the dominant damage is the general corrosion of the inner surface, the algorithm to receive the expression for the calculation of coefficients of the lowering of the supporting ability to the excessive inner pressure in the function of the nominal thickness of pipes wall and corrosion depth is shown. The algorithm of the application of the received expression to calculate the residual life of the damaged casing pipes is given.

Investigation on Material under Accelerated Simulator Environment in Laboratory and Tropical Marine Environment of Aircraft Structure

2011 ◽  
Vol 236-238 ◽  
pp. 2619-2625
Author(s):  
Yue Liang Chen ◽  
Jian Jun Hu ◽  
Gui Xue Bian ◽  
Yong Zhang ◽  
Hao Luo
Keyword(s):  
Mass Loss ◽  
Marine Environment ◽  
Base Material ◽  
Corrosion Damage ◽  
Aircraft Structure ◽  
Corrosion Characteristic ◽  
Accelerated Corrosion ◽  
Corrosion Depth ◽  
Ocean Environment ◽  
Damage Characteristic

The important factors induced corrosion damage of aircraft are analyzed. Based on airport ground environment spectrum, the LY12CZ specimens are tested in laboratory using the accelerated corrosion spectrum. Some specimens are exposed on deck in tropical marine environment. The corrosion characteristic of the coating and base material is inspected and corrosion damage size is measured after the specimens have been accelerated corrosion tested for 5,10,15,20 and 30 years respectively and the specimens have been exposed on deck. The corrosion characteristic of specimens are analyzed and compared using several evaluating indicator. The results show that the corrosion damage characteristic of the specimen in the test is consistent with which in service situations. And the corrosion of material exposed in ocean environment is obviously accelerated. The corrosion depth is measured and the mass loss by corrosion is weighed. The distribution function of the corrosion depth and the characteristic of the mass loss by corrosion are given. The corrosion equivalent relationship under these two environments is determined by contrasting the corrosion depth and the corrosion characteristic.

Pitting Degradation Modeling of Ocean Steel Structures Using Bayesian Network

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Jyoti Bhandari ◽  
Faisal Khan ◽  
Rouzbeh Abbassi ◽  
Vikram Garaniya ◽  
Roberto Ojeda
Keyword(s):  
Bayesian Network ◽  
Structural Steel ◽  
Marine Environment ◽  
Pitting Corrosion ◽  
Steel Structures ◽  
Poor Quality ◽  
Real World Data ◽  
Corrosion Depth ◽  
Operational Conditions

Modeling depth of long-term pitting corrosion is of interest for engineers in predicting the structural longevity of ocean infrastructures. Conventional models demonstrate poor quality in predicting the long-term pitting corrosion depth. Recently developed phenomenological models provide a strong understanding of the pitting process; however, they have limited engineering applications. In this study, a novel probabilistic model is developed for predicting the long-term pitting corrosion depth of steel structures in marine environment using Bayesian network (BN). The proposed BN model combines an understanding of corrosion phenomenological model and empirical model calibrated using real-world data. A case study, which exemplifies the application of methodology to predict the pit depth of structural steel in long-term marine environment, is presented. The result shows that the proposed methodology succeeds in predicting the time-dependent, long-term anaerobic pitting corrosion depth of structural steel in different environmental and operational conditions.

The Corrosion Evaluation Methodology of the Lock Gate

2014 ◽  
Vol 937 ◽  
pp. 105-108
Author(s):  
Chao Hua Jiang ◽  
Ke Fan ◽  
Xiang Yun Luo ◽  
Liang Qian
Keyword(s):  
Coating Thickness ◽  
Evaluation Methodology ◽  
Corrosion Depth ◽  
Corrosion Detection ◽  
Surrounding Environment ◽  
Corrosion Evaluation ◽  
Rating Method ◽  
Pit Depth ◽  
Environment Performance ◽  
Lock Gate

Influenced by surrounding environment, performance load and eroded by all kinds of media, the structure of lock gate prone to corrosion phenomena. Therefore, aimed at the situation of gate corrosion, to carry out the appraisal method for gate, a gate corrosion detection rating method is established. Based on the environment characteristics, taking corrosion appearance, coating thickness, the residue corrosion depth and corrosion pit depth as the index to evaluate,provides the judgment and evaluation basis for the lock gate is in need of repair.

Study on Corrosion Damage Rule for Two Type of Aluminum Alloy

2014 ◽  
Vol 599-601 ◽  
pp. 111-113
Author(s):  
Dan Feng Zhang ◽  
Xiao Ming Tan ◽  
Dan Gui Zhang ◽  
Fang Zhang ◽  
Wei Zhang
Keyword(s):  
Aluminum Alloy ◽  
Statistical Analysis ◽  
Marine Environment ◽  
Corrosion Test ◽  
Corrosion Damage ◽  
Aircraft Structure ◽  
Accelerated Corrosion ◽  
Damage Repair ◽  
Accelerated Corrosion Test ◽  
Damage Rule

Corrosion exists everywhere. It’s very widespread that the aluminum alloy aircraft structure suffers the corrosion damage under the marine environment particularly. The equivalent accelerated corrosion test of the new aluminum alloy 2B06 and 7B04 was carried out.Corrosion damage was inspected and measured through microscope. The rule of the corrosion damage can be obtained by statistical analysis. And which can supply the reference basis for the corrosion damage repair and evaluating the calendar life.

Effect on buckling behavior and seismic performance of steel piers corrosion-damaged near ground

2021 ◽  
Author(s):  
Takuma Rokutani ◽  
Kazutoshi Nagata ◽  
Takeshi Kitahara
Keyword(s):  
Seismic Performance ◽  
Rectangular Cross Section ◽  
Steel Structures ◽  
Corrosion Damage ◽  
Bridge Piers ◽  
Response Analysis ◽  
Steel Bridge ◽  
Seismic Response Analysis ◽  
Economic Miracle ◽  
Buckling Behavior

<p>In Japan, many steel structures were constructed during the period of the high economic miracle, and they are now more than 50 years old and are aging. Corrosion has been confirmed at corners and the boundary of concrete-wrapped concrete in steel piers. It was found that corrosion damage at the corner of steel piers causes a decrease of seismic performance in our previous investigations that carried out seismic response analysis. Subsequently, in this study, the effect of corrosion damage at the near ground edge of steel bridge piers with a rectangular cross-section was investigated in detail on the buckling behaviour and seismic performance of structures. As a result, it is found that the buckling at the base causes a decrease in load bearing performance compared to the buckling in the entire panel. It is necessary to properly maintain to prevent buckling at the base caused by corrosion.</p>

External Weld Overlays for Repair of Pressure Components

2003 ◽  
Author(s):  
Shane J. Findlan
Keyword(s):  
Weld Metal ◽  
Corrosion Damage ◽  
Microbiologically Influenced Corrosion ◽  
General Corrosion ◽  
Degradation Mechanisms ◽  
Weld Overlay ◽  
Metal Deposit ◽  
Wall Thinning ◽  
Erosion Corrosion ◽  
Weld Overlays

External weld metal deposit overlays have been successfully implemented in industry as both temporary and permanent repair for the restoration of thinning or degraded steel piping. Pressure components systems suffer from numerous degradation mechanisms, including microbiologically influenced corrosion (MIC), erosion-corrosion damage (EC), fatigue, and general corrosion. The magnitude of the damage induced in the component determines whether a weld overlay repair can be successfully applied to restore the component’s integrity. This paper addresses the use of weld overlays for repair of pressure components degraded by wall thinning due to corrosion, erosion-corrosion, MIC and other mechanisms.

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