Influence of hydrostatic pressure on the pitting corrosion behavior of API X80 steel

CORROSION ◽  
10.5006/3810 ◽  
2021 ◽  
Author(s):  
Chengcheng Xu ◽  
Yuxiang Zhu ◽  
Meng Yu ◽  
Ying Jin ◽  
Lei Wen ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Pitting Corrosion ◽  
Deep Sea ◽  
Cumulative Probability ◽  
Distribution Analysis ◽  
Kelvin Probe ◽  
Element Analysis ◽  
Test Steel ◽  
X80 Steel ◽  
Metastable Pitting

In this research, the effect of hydrostatic pressure on metastable and stable pitting corrosion of API X80 steel was investigated by using electrochemical method in simulated deep-sea environment. Cumulative probability distribution analysis of metastable pitting events revealed that hydrostatic pressure promoted the occurrence of metastable pitting corrosion and transformation trend of metastable pitting corrosion to stable pitting corrosion. Moreover, according to the results of scanning Kelvin probe force microscopy(SKPFM) tests, pitting corrosion of test steel can be confirmed to originate from the position of the interface between the inclusion and the substrate. Finally, combined with finite element analysis, the mechanism by which hydrostatic pressure promotes the occurrence and expansion of stable pitting corrosion of test steel in simulated deep -sea environment is explained.

scholarly journals A Statistical Study on the Effect of Hydrostatic Pressure on Metastable Pitting Corrosion of X70 Pipeline Steel

Materials ◽  
2017 ◽  
Vol 10 (11) ◽  
pp. 1307 ◽  
Author(s):  
Zixuan Yang ◽  
Bo Kan ◽  
Jinxu Li ◽  
Lijie Qiao ◽  
Alex A. Volinsky ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Pitting Corrosion ◽  
Statistical Study ◽  
Pipeline Steel ◽  
X70 Pipeline Steel ◽  
Metastable Pitting ◽  
Effect Of Hydrostatic Pressure

scholarly journals Failure Analysis on a Collapsed Flat Cover of an Adjustable Ballast Tank Used in Deep-Sea Submersibles

2019 ◽  
Vol 9 (23) ◽  
pp. 5258
Author(s):  
Fang Wang ◽  
Mian Wu ◽  
Genqi Tian ◽  
Zhe Jiang ◽  
Shun Zhang ◽  
...  
Keyword(s):  
Deep Sea ◽  
Material Selection ◽  
High Strength ◽  
External Pressure ◽  
Element Analysis ◽  
Ballast Tank ◽  
Material Inhomogeneity ◽  
Comprehensive Properties ◽  
Ultimate Cause ◽  
Flat Cover

A flat cover of an adjustable ballast tank made of high-strength maraging steel used in deep-sea submersibles collapsed during the loading process of external pressure in the high-pressure chamber. The pressure was high, which was the trigger of the collapse, but still considerably below the design limit of the adjustable ballast tank. The failure may have been caused by material properties that may be defective, the possible stress concentration resulting from design/processing, or inappropriate installation method. The present paper focuses on the visual inspections of the material inhomogeneity, ultimate cause of the collapse of the flat cover in pressure testing, and finite element analysis. Special attention is paid to the toughness characteristics of the material. The present study demonstrates the importance of material selection for engineering components based on the comprehensive properties of the materials.

A Study of the Sealing Performance of a New High-Pressure Cone Valve for Deep-Sea Gas-Tight Water Samplers

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Shi-Jun Wu ◽  
Can-Jun Yang ◽  
Ying Chen ◽  
Yan-Qing Xie
Keyword(s):  
Finite Element Analysis ◽  
High Pressure ◽  
Deep Sea ◽  
Hydrothermal Fluid ◽  
Contact Model ◽  
Element Analysis ◽  
Sea Trial ◽  
Sealing Performance ◽  
Pressure Cone ◽  
Gas Tight

The cone valve plays an important role in high-pressure sealing applications. In this paper, a new high-pressure cone valve, based on the titanium alloy poppet-to-polyetheretherketone seat sealing structure, is proposed for deep-sea gas-tight water samplers. In order to study the sealing performance of the new valve, both the conforming poppet-seat contact model and the nonconforming poppet-seat contact model were evaluated. Finite element analysis based on the two models was performed and validated by experiments. The results indicate that the nonconforming poppet-seat contact model has a better sealing performance than the conforming poppet-seat contact model. The new cone valve also was applied in a gas-tight hydrothermal fluid sampler and successfully tested in a sea trial during the KNOX18RR cruise from 9 July to 12 August 2008.

Finite Element Analysis of the Hydro-Mechanical Punching Process

2006 ◽  
Vol 505-507 ◽  
pp. 871-876
Author(s):  
Jong Hun Yoon ◽  
Hoon Huh ◽  
Yong Sin Lee ◽  
Seung Soo Kim ◽  
E.J. Kim ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Ductile Fracture ◽  
Sheet Material ◽  
Middle Surface ◽  
Initial Crack ◽  
Fracture Criteria ◽  
Element Analysis ◽  
Final Fracture ◽  
Ductile Fracture Criteria ◽  
Punching Process

This paper investigates the characteristics of a hydro-mechanical punching process. The hydro-mechanical punching process is divided into two stages: the first stage is the mechanical half piercing in which an upper punch goes down before the initial crack is occurred; the second stage is the hydro punching in which a lower punch goes up until the final fracture is occurred. Ductile fracture criteria such as the Cockcroft et al., Brozzo et al. and Oyane et al. are adopted to predict the fracture of a sheet material. The index value of ductile fracture criteria is calculated with a user material subroutine, VUMAT in the ABAQUS Explicit. The hydrostatic pressure retards the initiation of a crack in the upper region of the blank and induces another crack in the lower region of the blank during the punching process. The final fracture zone is placed at the middle surface of the blank to the thickness direction. The result demonstrates that the hydro-mechanical punching process makes a finer shearing surface than the conventional one as hydrostatic pressure increases.

scholarly journals Enhanced Hydrocarbons Biodegradation at Deep-Sea Hydrostatic Pressure with Microbial Electrochemical Snorkels

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 263
Author(s):  
Federico Aulenta ◽  
Enza Palma ◽  
Ugo Marzocchi ◽  
Carolina Cruz Viggi ◽  
Simona Rossetti ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Deep Sea ◽  
Sulfide Oxidation ◽  
Contaminated Sediments ◽  
Sulfide Concentration ◽  
Deep Sea Sediments ◽  
Toxicity Factor ◽  
Remote Environment ◽  
Additional Limitation ◽  
Oxide Sulfate

In anaerobic sediments, microbial degradation of petroleum hydrocarbons is limited by the rapid depletion of electron acceptors (e.g., ferric oxide, sulfate) and accumulation of toxic metabolites (e.g., sulfide, following sulfate reduction). Deep-sea sediments are increasingly impacted by oil contamination, and the elevated hydrostatic pressure (HP) they are subjected to represents an additional limitation for microbial metabolism. While the use of electrodes to support electrobioremediation in oil-contaminated sediments has been described, there is no evidence on their applicability for deep-sea sediments. Here, we tested a passive bioelectrochemical system named ”oil-spill snorkel” with two crude oils carrying different alkane contents (4 vs. 15%), at increased or ambient HP (10 vs. 0.1 MPa). Snorkels enhanced alkanes biodegradation at both 10 and 0.1 MPa within only seven weeks, as compared to nonconductive glass controls. Microprofiles in anaerobic, contaminated sediments indicated that snorkels kept sulfide concentration to low titers. Bulk-sediment analysis confirmed that sulfide oxidation by snorkels largely regenerated sulfate. Hence, the sole application of snorkels could eliminate a toxicity factor and replenish a spent electron acceptor at increased HP. Both aspects are crucial for petroleum decontamination of the deep sea, a remote environment featured by low metabolic activity.

The Combined Effect of Chemical and Structural Factors on Pitting Corrosion Induced by MnS-(Cr, Mn, Al)O Duplex Inclusions

CORROSION ◽  
10.5006/2581 ◽  
2017 ◽  
Vol 74 (3) ◽  
pp. 312-325 ◽  
Author(s):  
Cheng Man ◽  
Chaofang Dong ◽  
Kui Xiao ◽  
Qiang Yu ◽  
Xiaogang Li
Keyword(s):  
Pitting Corrosion ◽  
Selective Dissolution ◽  
Dissolution Mechanism ◽  
Structural Factors ◽  
Metal Interface ◽  
Kelvin Probe ◽  
Force Microscopy ◽  
Atomic Force ◽  
The Individual

In situ atomic force microscopy, scanning Kelvin probe force microscopy, and potential pulse technology were used to study the pitting behavior induced by inclusions in AM355 martensitic stainless steel. The MnS-(Cr, Mn, Al)O duplex inclusion exhibited the highest sensitivity to the pitting corrosion with respect to the individual MnS and (Cr, Mn, Al)O inclusions. When exposed to a solution containing Cl−, the selective dissolution occurred on the sulfide segment of the duplex inclusion, leading to trenching along the oxide part. The dissolution mechanism of MnS segment in the duplex inclusion is similar to the individual MnS inclusion. The Cr depletion in the boundary layer at the inclusion/metal interface promoted the transition from metastable to stable pitting corrosion in the duplex inclusion.

Solutions for Non-Newtonian Flow Into Elliptical Openings

1991 ◽  
Vol 58 (3) ◽  
pp. 820-824 ◽  
Author(s):  
A. Bogobowicz ◽  
L. Rothenburg ◽  
M. B. Dusseault
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Steady State ◽  
Hydrostatic Pressure ◽  
Velocity Field ◽  
Velocity Fields ◽  
Newtonian Flow ◽  
Element Analysis ◽  
Elliptical Opening ◽  
Elliptical Coordinates

A semi-analytical solution for plane velocity fields describing steady-state incompressible flow of nonlinearly viscous fluid into an elliptical opening is presented. The flow is driven by hydrostatic pressure applied at infinity. The solution is obtained by minimizing the rate of energy dissipation on a sufficiently flexible incompressible velocity field in elliptical coordinates. The medium is described by a power creep law and solutions are obtained for a range of exponents and ellipse eccentricites. The obtained solutions compare favorably with results of finite element analysis.

scholarly journals FabF Is Required for Piezoregulation ofcis-Vaccenic Acid Levels and Piezophilic Growth of the Deep-Sea Bacterium Photobacterium profundum Strain SS9

2000 ◽  
Vol 182 (5) ◽  
pp. 1264-1271 ◽  
Author(s):  
Eric E. Allen ◽  
Douglas H. Bartlett
Keyword(s):  
High Pressure ◽  
Hydrostatic Pressure ◽  
Deep Sea ◽  
Unsaturated Fatty Acids ◽  
Acyl Carrier Protein ◽  
Vaccenic Acid ◽  
Bacterial Species ◽  
Elevated Pressure ◽  
Wild Type ◽  
Photobacterium Profundum

ABSTRACT To more fully explore the role of unsaturated fatty acids in high-pressure, low-temperature growth, the fabF gene from the psychrotolerant, piezophilic deep-sea bacteriumPhotobacterium profundum strain SS9 was characterized and its role and regulation were examined. An SS9 strain harboring a disruption in the fabF gene (strain EA40) displayed growth impairment at elevated hydrostatic pressure concomitant with diminishedcis-vaccenic acid (18:1) production. However, growth ability at elevated pressure could be restored to wild-type levels by the addition of exogenous 18:1 to the growth medium. Transcript analysis did not indicate that the SS9 fabF gene is transcriptionally regulated, suggesting that the elevated 18:1 levels produced in response to pressure increase result from posttranscriptional changes. Unlike many pressure-adapted bacterial species such as SS9, the mesophile Escherichia coli did not regulate its fatty acid composition in an adaptive manner in response to changes in hydrostatic pressure. Moreover, an E. coli fabF strain was as susceptible to elevated pressure as wild-type cells. It is proposed that the SS9 fabF product, β-ketoacyl–acyl carrier protein synthase II has evolved novel pressure-responsive characteristics which facilitate SS9 growth at high pressure.

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