scholarly journals Analysis of Temperature Variations, Types of Insulation and Coating on Corrosion Under Insulation on ASTM A53 Pipes

2021 ◽  
Vol 2 (1) ◽  
pp. 110-118
Author(s):  
Reza Putra ◽  
Muhammad Muhammad ◽  
T Hafli ◽  
Nurul Islami ◽  
Arpan Apandi S
Keyword(s):  
Corrosion Rate ◽  
Ph Value ◽  
Test Method ◽  
Localized Corrosion ◽  
Test Time ◽  
Pipe Material ◽  
Uniform Corrosion ◽  
Temperature Variations ◽  
C 50 ◽  
Corrosion Under Insulation

Corrosion Under Insulation (CUI) can be described as localized corrosion that forms as a result of the penetration of water or moisture through an insulating material. The pipe material used is of the ASTM A53 standard and the fluid used in seawater because almost all industries are located on the coast. This type of coating is carried out on the test pipe using Meiji Epoxy Filler. The test method is carried out by flowing seawater fluid in pipes with water temperature variations of 30°C, 50°C, and 70°C. This pipe varies the type of insulation by using glasswool and Rockwool (ASTM G 189-07). This insulation is conditioned in a wet state by giving 2 ml of seawater drops with a pH value of 4 per 6 hours. The test equipment is divided into 3 series according to temperature variations with 4 test specimens and 2 coating variations respectively. The test time was carried out for 336 hours to obtain the corrosion rate results using the ASTM G31-72 weight loss method. The results showed that the type of Glasswool insulation with specimens coated had the lowest corrosion rate value of 0.00483 mmpy at a temperature of 30°C when compared to the same type of treatment on Rockwool insulation of 0.00724 mmpy or an increase of 2.41 times. This study shows that the type of insulation, temperature variation, and coating greatly affect the rate of corrosion and the type of corrosion that occurs is uniform corrosion.

The Calculation of the Thickness for Uniform Corrosion and Localized Corrosion in Steel Corrosion

2011 ◽  
Vol 255-260 ◽  
pp. 514-518
Author(s):  
Zheng Yi Kong ◽  
Shan Hua Xu ◽  
Yu Sheng Chen
Keyword(s):  
Corrosion Rate ◽  
Constant Temperature ◽  
Safety Assessment ◽  
Steel Corrosion ◽  
Localized Corrosion ◽  
Power Relationship ◽  
Uniform Corrosion ◽  
Experiment Data ◽  
Temperature And Humidity ◽  
Corrosion Pits

Because of the complexity of corrosion, the law of uniform corrosion and localized corrosion is still not clear,so it is difficult to assess their impact on the structure safety. In order to differ them and find their own law, we obtain a lot of corrosion specimens by ways of constant temperature and humidity, and then detect the size of corrosion pits by roughness tester. After that, the method for calculating the thickness of uniform corrosion and localized corrosion is proposed. Then the method is used to analyze the experiment data. The result indicates the thickness of uniform corrosion and localized corrosion all increase with the rate of corrosion, and they all show a power relationship with corrosion rate, so it will provide a basis for distinguishing them in safety assessment.

Maintenance Practices to Manage Corrosion Under Insulation (CUI) of Outdoor Piping Systems in Power Plants

2015 ◽  
Author(s):  
Joseph M. Mazzeo ◽  
Jeromy New
Keyword(s):  
Corrosion Rate ◽  
Power Plants ◽  
Conventional Radiography ◽  
Probability Of Failure ◽  
Pipe Diameter ◽  
Piping System ◽  
Pipe Material ◽  
Number Of Factors ◽  
Piping Systems ◽  
Corrosion Under Insulation

The outer walls of insulated pipes are susceptible to corrosion if the insulation stays wet for long periods of time. Corroded pipes have the potential for bursting without warning, releasing steam or combustibles and insulation debris which may contain asbestos, requiring significant cleanup and repairs. Managing the associated risks requires the consideration of a number of factors such as corrosion rates, examination methods, prioritization of inspection locations, and fitness for service evaluation and repair methods. A number of factors affect the corrosion rate such as pipe material and geometry, proximity to saltwater environments, local weather, and prevailing wind directions, as well as insulation type and condition. Some locations on the piping system require additional scrutiny, such as at pipe supports where rain water can cascade down hanger rods and into openings in the insulation, and at the bottom of vertical pipe runs where moisture is prone to becoming trapped in the insulation cladding. To prioritize inspection locations, risk factors such as exposure of personnel, the potential amount of energy released, the postulated corrosion rate and failure potential based on pressure and temperature need to be taken into account. The most susceptible materials are carbon and low alloy steel. Pressurized dead leg small bore pipes are of concern due to the small wall thickness and low operating temperatures that do not provide an opportunity to dry out the insulation. Digital Radiography Testing (DRT) through insulation provides excellent results for most 6” or less diameter piping systems. Highly sensitive digital exposure plates require less radiation compared to conventional Radiography, resulting in small radiation safety zones that allow work in surrounding areas to continue during inspection. The technique is effective for the evaluation of corroding fillet welds and threaded connections, and provides a digitized image that is database friendly. It provides information on pipe diameter and schedule, which aids in the preparation of repair sketches and bill of materials before an outage occurs. Repair options include replacement and operational changes which allow abandonment as well as improvements or elimination of insulation. Corrosion Under Insulation (CUI) damage is a significant issue at some plant sites where limited run time doesn’t allow the insulation to dry. In the near future, older, less economic base loaded plants that will run less frequently may fall into this category. To evaluate risk, the probability of failure needs to be considered with its potential consequence. For a pipe with CUI damage, probability of failure is dependent on the corrosion rate, pressure, pipe diameter, and thickness. The consequences are a potential injury and lost production.

Physical, Corrosion and Microstructural Analysis of A356/SiC Nanocomposites Fabricated through Stir Casting Process

2021 ◽  
Vol 1034 ◽  
pp. 73-86
Author(s):  
Md Tanwir Alam
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Microstructural Analysis ◽  
Casting Process ◽  
Stir Casting ◽  
Passive Layer ◽  
Test Method ◽  
Localized Corrosion ◽  
Aluminium Matrix ◽  
Sic Nanoparticles

Porosity is one of the main difficulty to fabricate the superior quality of aluminium matrix composites (AMCs) because it effects the surface finish of the casting, mechanical properties and corrosion resistance. Therefore, porosity must be minimum as possible so that better casting can be produced with optimal properties of the composites. In this study, aluminium matrix nanocomposites (A356/SiC or AMNCs) were fabricated through two-step stir casting via mechanical alloying using ball mill. The matrix alloy (A356) was reinforced with SiC nanoparticles of 40-55 nm avarage particle size (APS). The corrosion was performed by simple immersion corrosion test method for a predefined environment (3.5% NaCl solution) and for the specified duration. The results showed that density and porosity increase with the addition of reinforcement. The corrosion resistance get reduced with the incorporation of SiC due to the increase in porosity and number of nucleation sites. The substantial correlation between the corrosion rate and the amount of SiC are depicted. Moreover, the corrosion rate decreased with the increase in exposure time which is due to the formation of passive layer. The EDS spectrum shows the presence of different constituents in the composites. The formation of the cracks, oxides, pitting corrosion, and localized corrosion are found by the SEM results. Further, SEM of the corroded surface verifies the presence and good distribution of the SiC nanoparticles in the fabricated nanocomposites.

scholarly journals Corrosion Characteristics of Anchor Cables in Electrolytic Corrosion Test and the Applicability of the Test Method in Study of Anchor Cable Corrosion

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Tao Yin ◽  
Xingsong Sun ◽  
Yujie Wang ◽  
Yufei Zhao ◽  
Shuangjing Wang ◽  
...  
Keyword(s):  
Sodium Chloride ◽  
Corrosion Test ◽  
Chloride Concentration ◽  
Test Method ◽  
Test Time ◽  
Uniform Corrosion ◽  
Corrosion Study ◽  
Anchor Cable ◽  
Electrolytic Corrosion ◽  
The Difference

The selection of corrosion test method in the corrosion study of the prestressed anchors is an important issue. In this paper, the corrosion test of anchors was conducted with electrolytic corrosion test method. The corrosion characteristics of the anchor cables were examined. The effects of sodium chloride solution concentration, current, test time, and prestress level on corrosion were studied. The applicability of electrolytic corrosion method in anchor cable corrosion study is discussed subsequently. The results show that the corrosion of the anchor appears to be uniform corrosion. With the corrosion of the anchor, the central wire of the cable was basically not corroded, and the cross-sectional shape of the outer wire changes from a round to fan shape. The sodium chloride concentration and prestress level have no obvious effects on the corrosion of the anchor. The variation of test time does not affect the difference between the measured and theoretical calculated results, while a proper current in the electrolysis test may help reduce the difference. The measured corrosion rate fluctuates from −4% to 10% and tends to be higher compared with calculated results based on Faraday’s law. The study indicates that the electrolytic corrosion test is applicable in the anchor corrosion study.

scholarly journals Electrochemical metrics for corrosion resistant alloys

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Clara Nyby ◽  
Xiaolei Guo ◽  
James E. Saal ◽  
Szu-Chia Chien ◽  
Angela Y. Gerard ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Current Density ◽  
Crevice Corrosion ◽  
Corrosion Potential ◽  
Corrosion Current ◽  
Localized Corrosion ◽  
Uniform Corrosion ◽  
Pitting Potential ◽  
Corrosion Resistant ◽  
High Entropy

AbstractCorrosion is an electrochemical phenomenon. It can occur via different modes of attack, each having its own mechanisms, and therefore there are multiple metrics for evaluating corrosion resistance. In corrosion resistant alloys (CRAs), the rate of localized corrosion can exceed that of uniform corrosion by orders of magnitude. Therefore, instead of uniform corrosion rate, more complex electrochemical parameters are required to capture the salient features of corrosion phenomena. Here, we collect a database with an emphasis on metrics related to localized corrosion. The six sections of the database include data on various metal alloys with measurements of (1) pitting potential, Epit, (2) repassivation potential, Erp, (3) crevice corrosion potential, Ecrev, (4) pitting temperature, Tpit, (5) crevice corrosion temperature, Tcrev, and (6) corrosion potential, Ecorr, corrosion current density, icorr, passivation current density, ipass, and corrosion rate. The experimental data were collected from 85 publications and include Al- and Fe-based alloys, high entropy alloys (HEAs), and a Ni-Cr-Mo ternary system. This dataset could be used in the design of highly corrosion resistant alloys.

scholarly journals Investigation of Corrosion Rate and Rust Expansion Form of Segment Reinforcement for Shield Tunnel by Combined Action of Soil Loading, Chloride Ion and Stray Current

2021 ◽  
Vol 13 (6) ◽  
pp. 3444
Author(s):  
Zheng Li ◽  
Hao Jin ◽  
Shuo Yu
Keyword(s):  
Corrosion Rate ◽  
Steel Corrosion ◽  
Chloride Ion ◽  
Shield Tunnel ◽  
Uniform Corrosion ◽  
Stray Current ◽  
Soil Loading ◽  
Capacity Degradation ◽  
Expansion Form ◽  
Combined Action

Segment reinforcement corrosion can cause bearing-capacity degradation of shield tunnel, which is unsafe for the metro operation. Therefore, a three-dimensional computational model was proposed in this paper to study the corrosion rate and rust expansion form of segment reinforcement by the combined action of soil loading, chloride ion and stray current. The results show that the arch waist segment steel corrosion rate in the middle is larger than the ends. The rust expansion form of segment reinforcement appears be an eccentric circle. The radius size and circular center are related to the non-uniform corrosion coefficient and the maximum corrosion current density.

scholarly journals Corrosion Behavior of LENS Deposited CoCrMo Alloy Using Bayesian Regularization-Based Artificial Neural Network (BRANN)

2021 ◽  
Vol 7 (3) ◽  
Author(s):  
Nagoor Basha Shaik ◽  
Kedar Mallik Mantrala ◽  
Balaji Bakthavatchalam ◽  
Qandeel Fatima Gillani ◽  
M. Faisal Rehman ◽  
...  
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Corrosion Rate ◽  
Prediction Models ◽  
Test Time ◽  
Bayesian Regularization ◽  
Cobalt Chromium ◽  
Corrosion Properties ◽  
Cocrmo Alloy ◽  
Artificial Neural

AbstractThe well-known fact of metallurgy is that the lifetime of a metal structure depends on the material's corrosion rate. Therefore, applying an appropriate prediction of corrosion process for the manufactured metals or alloys trigger an extended life of the product. At present, the current prediction models for additive manufactured alloys are either complicated or built on a restricted basis towards corrosion depletion. This paper presents a novel approach to estimate the corrosion rate and corrosion potential prediction by considering significant major parameters such as solution time, aging time, aging temperature, and corrosion test time. The Laser Engineered Net Shaping (LENS), which is an additive manufacturing process used in the manufacturing of health care equipment, was investigated in the present research. All the accumulated information used to manufacture the LENS-based Cobalt-Chromium-Molybdenum (CoCrMo) alloy was considered from previous literature. They enabled to create a robust Bayesian Regularization (BR)-based Artificial Neural Network (ANN) in order to predict with accuracy the material best corrosion properties. The achieved data were validated by investigating its experimental behavior. It was found a very good agreement between the predicted values generated with the BRANN model and experimental values. The robustness of the proposed approach allows to implement the manufactured materials successfully in the biomedical implants.

scholarly journals Wear and Corrosion of Wrought A6061 Aluminium Alloy in DOT3 Brake Fluid

2018 ◽  
Vol 7 (2.14) ◽  
pp. 512 ◽  
Author(s):  
Olawale Ajibola ◽  
Oladeji Ige ◽  
Peter Olubambi
Keyword(s):  
Corrosion Rate ◽  
Test Method ◽  
Alloy Sample ◽  
Corrosive Media ◽  
Chemical Corrosion ◽  
Brake Fluid ◽  
Wear And Corrosion ◽  
Cast Specimen ◽  
Fluid Environment ◽  
A6061 Alloy

The twofold impact of wear and corrosion on wrought A6061 alloy in hydraulic DOT3 brake fluid environment was studied. The wear studies were performed on the samples using a developed wear-jig. Weight loss corrosion test method was used to determine the corrosion rate of the wrought A6061 alloy samples immersed in the brake fluid for a total of 1680 hours. From the results of wear tests carried out on the A6061 alloy sample with brake oil, the highest wear value of 5.24x10-7 mg/mm2/cycle (approx.) was obtained from 6 N (approx) force after 130 minutes. The wrought A6061 alloy material demonstrated the highest corrosion rates nearly 3.0 x10-2 mg/mm2/yr within the early 168 hours of immersion in brake fluid. The result is practically lower than the corrosion rate of cast specimen in DOT3 brake oil or some other alloys immersed in other corrosive media that were previously reported in the literature. The results show that small amount of chemical corrosion is sufficient to cause and accelerate mechanical wear of the material in usage.

scholarly journals ASESMEN KOROSI & ANALISIS RISIKO KUALITATIF PADA VERTIKAL BEJANA TEKAN

2021 ◽  
Vol 8 (2) ◽  
pp. 63-72
Author(s):  
Amam Fachrur Rozie ◽  
D.N Adnyana
Keyword(s):  
Risk Analysis ◽  
Corrosion Rate ◽  
Pressure Vessel ◽  
Atmospheric Corrosion ◽  
Uniform Corrosion ◽  
Vertical Pressure ◽  
Qualitative Risk Analysis ◽  
Non Destructive ◽  
Design Pressure

Keselamatan dan keamanan dalam penggunaan bejana tekan sangat penting dan hal utama dalam penggunaan bejana tekan, terlebih lagi jika bejana tekan tersebut sudah melewati umur desain nya. Penelitian ini bertujuan untuk menilai kelayakan kondisi terkini dari suatu bejana tekan vertikal (vertical pressure vessel) yang telah beroperasi sejak tahun 1970 tetapi berhenti beroperasi pada tahun 2011. Pendekatan penilaian pada bejana tekan vertikal ini berbasis pada metode penilaian korosi dan risiko secara kualitatif. Selain itu juga dipergunakan metode-metode lain dalam aspek penilaian nya seperti visual inspeksi, laju korosi (corrosion rate), Non-Destructive Examination (NDE), software calculation dan analisa risiko kualitatif (qualitative risk analysis). Dari hasil observasi dan inspeksi di dapat tekanan desain (design pressure) adalah 7 kg/cm2, Temperatur desain (design temperature) adalah 61°C dengan material konstruksi adalah SA-283 Gr. C dan standard & code yang dipergunakan adalah ASME Sect. VIII Div. 1 dan API 510 serta beberapa standard & code lainnya. Dari hasil kajian dan kalkulasi di lapangan, maka didapat faktor penyebab kerusakan yang kemungkinan terjadi adalah atmospheric corrosion & uniform corrosion dengan nilai laju korosi adalah sebesar 0,127mm/yr dan tingkat risiko dari bejana tekan vertikal ini masuk dalam kategori 2D yang artinya adalah medium-high dengan maksimal umur pakai sampai usia 27 tahun untuk top head dan 24 tahun dan bottom head serta 23 tahun untuk shell. Sehingga dapat disimpulkan bahwa bejana tekan ini masih aman dan layak dipergunakan dengan batasan-batasan di atas.

scholarly journals Corrosion of Mechanically Alloyed Nanostructured FeAl Intermetallic Powders

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
A. Torres-Islas ◽  
C. Carachure ◽  
S. Serna ◽  
B. Campillo ◽  
G. Rosas
Keyword(s):  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Corrosion Current ◽  
Test Time ◽  
Uniform Corrosion ◽  
Mechanically Alloyed ◽  
Solution Ph ◽  
Surface Corrosion ◽  
Electrochemical Testing

The corrosion behavior of the Fe40Al60nanostructured intermetallic composition was studied using electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LPR) techniques with an innovative electrochemical cell arrangement. The Fe40Al60(% at) intermetallic composition was obtained by mechanical alloying using elemental powders of Fe (99.99%) and Al (99.99%). All electrochemical testing was carried out in Fe40Al60particles that were in water with different pH values. Temperature and test time were also varied. The experimental data was analyzed as an indicator of the monitoring of the particle corrosion current densityicorr. Different oxide types that were formed at surface particle were found. These oxides promote two types of surface corrosion mechanisms: (i) diffusion and (ii) charge transfer mechanisms, which are a function oficorrbehavior of the solution, pH, temperature, and test time. The intermetallic was characterized before and after each test by transmission electron microscopy. Furthermore, the results show that at the surface particles uniform corrosion takes place. These results confirm that it is possible to sense the nanoparticle corrosion behavior by EIS and LPR conventional electrochemical techniques.

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