scholarly journals Corrosion Failure Mechanism of Associated Gas Transmission Pipeline

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1935 ◽  
Author(s):  
Weimin Zhao ◽  
Timing Zhang ◽  
Yonglin Wang ◽  
Jianhua Qiao ◽  
Zerui Wang
Keyword(s):  
Corrosion Rate ◽  
Gas Pipeline ◽  
Corrosion Products ◽  
Oxygen Absorption ◽  
Co2 Corrosion ◽  
Uniform Corrosion ◽  
X Ray Diffraction ◽  
Corrosion Failure ◽  
Associated Gas ◽  
Transmission Pipeline

Corrosion has been responsible for several gas pipeline leakage accidents; thus, clarifying its failure mechanisms is a precondition to prevent such accidents. On the basis of failure analysis of corroded pipe sections, laboratory exposure tests were conducted by simulating three possible corrosion environments inside a gas pipeline. The corrosion rate indicated by depth change was adopted in this study. Scanning electron microscopy and X-ray diffraction were used to analyze corrosion products. Results showed that the specimens completely immersed in condensate water were generally corroded and that the specimens exposed to gas were locally corroded. However, the corrosion rate of the latter was slightly lower; hence, no autocatalysis of occluded corrosion cell occurred in the formation of corrosion pit, and uniform corrosion occurred in the precipitation location of condensate water. The areas in the range of 5 mm below the waterline indicated severe corrosion, and the rate could reach twice that of other areas. The corrosion products were mainly FeO(OH) and FeCO3, thereby proving that the corrosion failure of pipelines was caused by oxygen absorption corrosion and CO2 corrosion. Suggestions were presented to control corrosion failure of associated gas pipelines.

scholarly journals USING WIRE BEAM ELECTRODE (WBE) TO EVALUATE THE CORROSION BEHAVIOR OF ND STEEL IN ACID MEDIUM

2020 ◽  
Vol 1 (2) ◽  
pp. 27-30
Author(s):  
Bo Zhao ◽  
Yuxin Yu ◽  
Jing Guo ◽  
Tianyu Zhou ◽  
Shiwen Zou ◽  
...  
Keyword(s):  
Partial Pressure ◽  
Corrosion Behavior ◽  
Ring Structure ◽  
Corrosion Products ◽  
Dew Point ◽  
Co2 Corrosion ◽  
Uniform Corrosion ◽  
Corrosion Morphology ◽  
Co2 Partial Pressure ◽  
Wire Beam Electrode

In this article, wire beam electrode (WBE) was used to evaluate the corrosion behavior of ND steel in environmental acid atmosphere with different partial pressure of CO2. Meanwhile, corrosion products and surface morphology analysis also used to support this research. The results showed that the corrosion behavior began from the edge of droplet in dew point corrosion, and gradually spread to the center of it. The spread speed would be increasing with CO2 partial pressure enhance, which was 24h in 5% CO2 and 4h in 50% CO2. Corrosion current density in the edge of droplet can form the “cathode-anode-cathode ring” structure and disappears gradually as the corrosion time was going. Corrosion morphology observation results showed three ring shapes region and different elemental composition of different corrosion products, which is correspondence with the “cathode-anode We-cathode ring” structure measured in WBE experiments. The results showed that the reaction gradually transferred to the uniform corrosion on electrode surface when the dew point corrosion reaction reaching the late stage. It comes from the dissolution, diffusion and reaction of gaseous corrosion medium of CO2 and O2.

Microbiologically Influenced Corrosion Combined with Under-Deposit Corrosion Mechanism and Control Technology in Water Injection Wells of Middle East Carbonate Oilfield

2021 ◽  
Author(s):  
Zhengrong Ye ◽  
Huachang Chi ◽  
Xiang Zhou ◽  
Zhiwen Yang ◽  
Weidong Jiang ◽  
...  
Keyword(s):  
Middle East ◽  
Corrosion Rate ◽  
High Salinity ◽  
Water Injection ◽  
Corrosion Products ◽  
Microbiologically Influenced Corrosion ◽  
Corrosion Mechanism ◽  
Corrosion Prevention ◽  
High Hydrogen ◽  
Corrosion Failure

Abstract A carbonate oilfield in the Middle East carries out the mixed water injection of produced water and fresh water, after 1 year of its rapid exploration. The injected water is highly corrosive, with high salinity, high chloride concentration and high hydrogen sulfide. Recently, there are dozens of corrosion perforations on L80 tubing in injectors within 2 years in the field and the corrosion rate reaches 3.6 mm/a. After the tubing leaks, the injected water enters into the annulus between the tubing and casing, which causes casing corrosion, damages the well integrity, and greatly influences the field production. In this paper, the causes for such rapid tubing corrosion failure are investigated by using optical metallographic microscopy, scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) X-ray diffraction (XRD), and combined with the weight loss and bacteria testing. Firstly, test the element composition of the L80 tubing to verify the tubing quality. Secondly, conduct the corrosion experiments of H2S and dissolved oxygen. Thirdly, analyze the morphology and corrosion product composition of failure tubing. The results indicate that the failed L80 tubing material meets the requirements of API SPEC 5CT-2011 standard. The localized corrosion rate of L80 is 0.293~0.697 mm/a at whole well depth in the simulated injection water. Bacteria were detected in both the injected water and the corrosion products of the failed tubing. In addition, the corrosion products of failed tubing are mainly FeS, CaCO3 and Fe3O4, which indicates that the synergistic effect of microbiologically influenced corrosion and under-deposited corrosion promote the perforation of tubing. Then the corrosion prevention strategy of UHMWPE lined tubing was proposed. UHMWPE lined tubing has been applied in nine water injectors. After one year and a half, one of the water injector’s UHMWPE lined tubing has been detected, no corrosion perforations observed, and the scale deposition became slightly. This case provides useful practical experience for corrosion prevention of high salinity and high acid injection well in carbonate oilfields.

Corrosion Inhibition Mechanism of Magnetic Field on Carbon Steel

2010 ◽  
Vol 152-153 ◽  
pp. 353-356
Author(s):  
Peng Zhang ◽  
Gang Chen ◽  
Bin Guo ◽  
Shu Kang Cheng
Keyword(s):  
Magnetic Field ◽  
Corrosion Rate ◽  
Sea Water ◽  
Electrochemical Corrosion ◽  
Water Relation ◽  
Corrosion Products ◽  
Alternating Magnetic Field ◽  
Inhibition Mechanism ◽  
X Ray Diffraction ◽  
Corrosion Morphology

The current research explores the effect of alternating magnetic field on corrosion rate and products compositions of 45 steel, by use of electrochemical test, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The calculated inhibition efficiency of the alternating magnetic field based on electrochemical corrosion rate is up to 16.66%. Electrochemical corrosion morphology and surface products were also discussed. The surface of specimen is uniform and compact in magnetized sea water relation to that in 3.5% NaCl solution and sea water. The corrosion products of 45 steel in sea water are FeCl2•4H2O, Fe(OH)3 and FeOOH. However, the corrosion products of 45 steel in magnetized sea water are FeOOH, Fe3O4 and FeCl3•6H2O chiefly.

Effect of Temperature on H2S/CO2 Corrosion Behaviors of P110-3Cr Steel

2013 ◽  
Vol 816-817 ◽  
pp. 54-59 ◽  
Author(s):  
Xin Su ◽  
Jian Bo Sun ◽  
Chong Sun ◽  
Bin Han
Keyword(s):  
Corrosion Rate ◽  
Corrosion Product ◽  
Iron Sulfide ◽  
Energy Dispersive Spectrometer ◽  
Corrosion Products ◽  
Effect Of Temperature ◽  
General Corrosion ◽  
X Ray Diffraction ◽  
X Ray ◽  
Corrosion Behaviors

Flowing solution environment containing H2S/CO2was simulated by high temperature and high pressure autoclave. Corrosion behaviors of P110-3Cr pipeline steels were investigated by Weight loss, Scanning electron microscopy (SEM), X-Ray diffraction (XRD) and Energy dispersive spectrometer (EDS). Effect of temperature on corrosion rate and corrosion product was discussed. The results showed that corrosion rate of P110-3Cr steel decrease at the beginning and then increased with rising temperature. The corrosion types are general corrosion. P110-3Cr has resistance to local corrosion. Mackinawite (FeS0.9) is formed as corrosion product in low-temperature condition. With temperature increasing the corrosion products are dominated by mackinawite (FeS0.9) and Cubic iron sulfide (Fe3S4). When temperature increased to 150 ¡æ, the corrosion products are made up of Hexagonal iron sulfide (Fe0.96S) and Orthorhombic Marcasite (FeS2). No siderite (FeCO3) is detected, the corrosion is controlled by H2S; Cr is rich in the corrosion scale.

Corrosion analysis of copper T2 exposed to polluted atmospheres and study on prediction model

2017 ◽  
Vol 35 (1) ◽  
pp. 35-46 ◽  
Author(s):  
Zhiping Zhu ◽  
Xiandi Zuo ◽  
Zhaohui Ying
Keyword(s):  
Corrosion Rate ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Corrosion Products ◽  
Good Prediction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Early Stages ◽  
Metal Materials ◽  
The Mathematical Model

AbstractThe power supply accident caused by the corrosion of metal materials in the substation has become an important issue that affects the safe operation of the power grid. The corrosion of copper T2 was the most serious. The corrosion behaviour of copper T2 in SO2- and H2S-containing atmospheric environments was investigated using electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD), and the nonequidistant grey GM(1,1) model was established of which the precision and forecast dependability were evaluated. Results indicated that the corrosion rate of copper in the SO2 environment increased in the early stages of corrosion and then gradually decreased at the later stages. In contrast, the corrosion rate of copper in the H2S environment slowly increased in the early stages of corrosion and then sharply increased at the later stages. The corrosion products in the SO2 environment consisted of cuprite (Cu2O) and brochantite [Cu4(OH)6SO4], whereas the corrosion products in the H2S environment were Cu2O and chalcocite (Cu2S). The mathematical model has good prediction dependability and higher forecast reliability.

Corrosion Failure Analysis of a New L360 Pipeline

2016 ◽  
Vol 850 ◽  
pp. 930-936
Author(s):  
Xin Su ◽  
Feng Wang ◽  
Yu Ran Fan ◽  
Yan Chun Zhang ◽  
Qing Lai Chen
Keyword(s):  
Chemical Constituents ◽  
Optical Microscope ◽  
Corrosion Products ◽  
Combined Effects ◽  
X Ray Diffraction ◽  
Simulation Test ◽  
Corrosion Failure ◽  
X Ray ◽  
Inner Surface ◽  
Corrosion Pits

In this paper, the optical microscope, scanning electron microscope (SEM), X-ray Diffraction (XRD) and simulation test were utilized to study the corrosion failure of L360 pipeline. The results show that the corrosion pits distributed around the pipe inner surface. The pipe mechanical properties, chemical constituents and inclusions grade satisfied the requirements of the technical conditions. Inclusions were composed of Ca, S, Al and O. Corrosion products consisted of the Fe3O4, Fe2O3 and FeO (OH). The compositions of corrosion products within and around the pits were similar to the inclusions. Due to the combined effects of water and high pressure air sealed in the pipeline, the pits formed around inclusions, and developed into occluded cells which accelerating the corrosion and leading to the failure finally.

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.

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.

Alloy Design of New Ni-Based Structural Materials for Electrolytic Reduction and its Corrosion Behavior in Lithium Molten Salt

2014 ◽  
Vol 886 ◽  
pp. 41-44 ◽  
Author(s):  
Sang Kyu Park ◽  
Tae Hyuk Lee ◽  
Moon Soo Sim ◽  
Jae Soo Noh ◽  
Soo Haeng Cho ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Molten Salt ◽  
Corrosion Behavior ◽  
Structural Materials ◽  
Solute Concentration ◽  
Inert Atmosphere ◽  
Electrolytic Reduction ◽  
Corrosion Products ◽  
Alloy Formation ◽  
Lithium Molten Salt

In this study, the corrosion behavior of new Ni-based structural materials was studied for electrolytic reduction after exposure to LiCl-Li2O molten salt at 650°C for 24-216h under an oxidizing atmosphere. The new alloys with Ni, Cr, Al, Si, and Nb as the major components were melted at 1700°C under inert atmosphere. The corrosion products and fine structures of the corroded specimens were characterized by SEM, EDS, and XRD. The corrosion rate of 12wt% Cr-2wt% Si alloys and 12wt% Cr-5wt% Si alloys are below 0.3mm/year. However, the corrosion rate of 20wt% Cr-5wt% Si is 0.6mm/year. Also, the corrosion products of 12wt% Cr alloys were Cr2O3, NiCr2O4, Ni, and NiO; those of 20wt% Cr alloys were Cr2O3, LiAl2Cr3O8, and NiO. The higher corrosion rate of 20wt% Cr-5wt% Si could be the higher solute concentration which leads to an unstable alloy formation. As confirmed by the pseudo binary phase diagram of (Ni-Cr-Al-Nb)-Si, the solubility of the silicon with 20 wt% of Cr decreased to 4 wt% from 5 wt% with 12 wt% of Cr.

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