Influence of Mechanical and Chemical Factors on Transition Between Severe and Mild Wear in Saline Solution

1997 ◽  
Vol 119 (4) ◽  
pp. 619-625 ◽  
Author(s):  
H. Goto
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Content ◽  
Cathodic Protection ◽  
Saline Solution ◽  
Concentration Level ◽  
Applied Potential ◽  
Severe Wear ◽  
Saturated Condition ◽  
Mild Wear ◽  
Chemical Factors

Pin-on-disk wear tests of carbon steels in saline solution were carried out at high loads to study the effects of mechanical and chemical factors on the transition between severe and mild wear. The factors were load, presliding time, concentration of saline solution, dissolved oxygen content, and applied potential for cathodic protection. Severe wear and seizure appear at low concentration levels of saline solution and the transition takes place at a certain concentration level of saline solution. The concentration level for the transition is higher under argon-saturated condition than under air-saturated condition. Mild wear is predominant over the whole range of dissolved oxygen content from 0.5 to 18 ppm in 0.5 wt percent saline solution and the wear rate decreases with decreasing dissolved oxygen content. The mild wear occurs in the range from 2 to 18 ppm in 0.01 wt percent saline solution, whereas the wear mode moves to severe wear below 2 ppm. Mild wear predominates under incomplete cathodic protection between −0.50 and −0.80 V (versus Ag/AgCl in 0.5 wt percent saline solution. The applied potential for the transition from initial to steady wear is more negative under higher dissolved oxygen content condition. Complete severe wear occurs below −0.90 V (versus Ag/AgCl) with a risk of seizure.

A hybrid model for short-term dissolved oxygen content prediction

2021 ◽  
Vol 186 ◽  
pp. 106216
Author(s):  
Jiande Huang ◽  
Shuangyin Liu ◽  
Shahbaz Gul Hassan ◽  
Longqin Xu ◽  
Cifeng Huang
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Content ◽  
Hybrid Model ◽  
Short Term

Effect of Dissolved Oxygen Content on Gelling Strength of Chromium Gel in Block Hai 1

2014 ◽  
Vol 1008-1009 ◽  
pp. 243-246
Author(s):  
Peng Fei Yuan ◽  
Guang Sheng Cao ◽  
Xiao Ma ◽  
Xiao Ping Wang ◽  
Xin Tian
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Content ◽  
Good Effect ◽  
Factors Affecting ◽  
Profile Control ◽  
Liaohe Oilfield ◽  
Weak Gel ◽  
Main Factors ◽  
Implementation Effect ◽  
Gelling Time

Jinma company of Liaohe oilfield has carried out weak gel flooding in-depth in block Hai1 and achieved good effect. But in the process of profile and flooding, problems of gelation fluctuating and gelling rate declining seriously affected the implementation effect of the profile control and flooding project. It is researched that one of main factors affecting gelling effect of profile and flooding system is the dissolved oxygen. Aiming at this problem, this paper studies critical value affecting gelling in combination with the actual situation of polymer displacement in block Hai 1. The experimental results show that, content of dissolved oxygen affects both gelling strength and gelling time of weak gel in the way that when dissolved oxygen content is between 0mg/L and 3mg/L, low gelling strength and long gelling time are obtained, while in the range of 4mg/L-10mg/L, gelling effect is good. Two critical values are respective 1.5mg/L and 7mg/L.

Corrosion Risk and Repassivation of Duplex Stainless Steel UNS S82551 in Treated Seawater Injection Service

CORROSION ◽  
10.5006/3697 ◽  
2021 ◽  
Author(s):  
Nicolas Larche ◽  
Perry Nice ◽  
Hisashi Amaya ◽  
Lucrezia Scoppio ◽  
Charles Leballeur ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Dissolved Oxygen ◽  
Duplex Stainless Steel ◽  
Oxygen Content ◽  
Alloy Steel ◽  
Stainless Steels ◽  
Crevice Corrosion ◽  
Low Alloy Steel ◽  
Corrosion Risk ◽  
Service Conditions

In seawater injection wells, the available well tubing materials are generally Low alloy steel, Glass Reinforced Epoxy lined low alloy steel or Corrosion Resistant Alloy’s (CRA) such as super duplex stainless steel. However, in treated seawater the corrosion risk can be controlled and lower grade alloys (low alloy steel) can be considered. But for long well lifetime designs (20 years plus), then low alloy steel tubing can be challenged. In this respect recent efforts have focused attention on better dissolved oxygen control which permits the investigation and on the possible use of more cost-effective materials such as the duplex stainless steels UNS S82551, and UNS S82541 (the latter is a higher strength version, but same PRENw). Full scale testing of tubes joined together with a proprietary premium threaded connection (PCPC couplings) was performed in controlled seawater loops simulating service conditions at 30°C. The flow rate and dissolved oxygen were controlled at 5 m/s and <20ppb, respectively. Weekly dissolved oxygen excursions corresponding to 24h at 100ppb followed by 1 hour at 300ppb were performed during the 5 months exposure. Corrosion results of UNS S82551/S82541 tubing were compared to UNS S31803 and UNS S39274. In parallel, laboratory exposures of creviced coupons for parametric study were performed in dissolved oxygen-controlled cells, allowing the measurement of electrochemical potentials as function of dissolved oxygen content and the related corrosion resistance. The results showed that dissolved oxygen content should be properly controlled below critical values to avoid crevice corrosion of the lesser alloyed duplex stainless steels. The ability of UNS S82541 to recover or re-passivate after prolonged exposures to high dissolved oxygen concentrations (DOC) was also determined with both the use of full sized pipe-coupling premium connection (PCPC) test cells, and electrochemical testing involving a Remote Crevice Assembly (RCA). The re-passivation potential was investigated after different active crevice corrosion durations. The results of the study allowed to precisely define the limits of use of UNS S82541 in treated seawater, i. e. the critical DOC conditions for corrosion initiation and for re-passivation of UNS S82541. For all tested conditions, the UNS S82551/S82541 showed a rather good ability to re-passivation when normal service conditions (i. e. low dissolved oxygen) are recovered.

scholarly journals Morphofunctional changes of phytoplankton community during pluvial anomaly in a tropical reservoir

2015 ◽  
Vol 75 (3) ◽  
pp. 628-637 ◽  
Author(s):  
FRA Câmara ◽  
O Rocha ◽  
EKR Pessoa ◽  
S Chellappa ◽  
NT Chellappa
Keyword(s):  
Species Diversity ◽  
Dissolved Oxygen ◽  
Oxygen Content ◽  
Phytoplankton Community ◽  
Diversity Index ◽  
Hydrodynamic Instability ◽  
Electrical Conductance ◽  
Northeastern Brazil ◽  
Tropical Reservoir ◽  
Cyanobacterial Species

AbstractThe present study focuses on the structure and function of phytoplankton community during periods of marked changes in hydrological traits, influenced by an atypical climatic event (La Niña) and its impact on Armando Ribeiro Gonçalves Reservoir of Rio Grande do Norte, situated in the Caatinga biome of northeastern Brazil. The main questions addressed were: What are the effects of environmental factors on the temporal variation of Morphologically Based Functional Group (MBFG) of phytoplankton community? How does the composition of cyanobacterial species shift in relation to high and low trends of phytoplankton diversity? The samples were collected monthly during 2008-2009 and analyzed for pH, temperature, electrical conductivity, dissolved oxygen content and the nutrients, such as, nitrate-nitrogen, ammoniacal nitrogen, total nitrogen and orthophosphate. Phytoplankton samples were collected for both qualitative and quantitative analyses to evaluate species richness index and species diversity index. The data was divided into two distinct hydrodynamic periods of instability and stability. The results demonstrate considerable changes in dissolved oxygen content, water transparency and nitrogen nutrients, which directly influenced the MBFG of phytoplankton community in space and time. The instability of reservoir water was caused by heavy rainfall, which exerts atypical external disturbances. The seasonal variation of MBFG demonstrates a change in cyanobacterial composition and their diversity during instability and stability periods. MBFG VII, composed by colonial cyanobacteria with mucilage, was associated with reduced values of electrical conductance and alterations in pH. The predominance of filamentous species with heterocyst (MBFG III) occurs only during the hydrodynamic stability period and did not show significant association with analyzed parameters. The co-dominance of MBGFs III, V and VII along with high species diversity of phytoplankton community occurred during the second hydrodynamic instability period which was associated with the reduction in water temperature. It is concluded that the decrease in cyanobacterial species dominance and the general increase in the diversity of phytoplankton community are influenced by pluvial anomaly. The higher water level during the period of pluvial anomaly resulted in nutrient pulse and the mixing of water column in the reservoir, which determined the MBPG phytoplankton community distribution.

Transition of Mild Wear to Severe Wear in Oxidative Wear of H21 Steel

2008 ◽  
Vol 32 (2) ◽  
pp. 67-72 ◽  
Author(s):  
S. Q. Wang ◽  
M. X. Wei ◽  
F. Wang ◽  
X. H. Cui ◽  
C. Dong
Keyword(s):  
Oxidative Wear ◽  
Severe Wear ◽  
Mild Wear

scholarly journals Abundance and diversity of black flies (Diptera: Simuliidae) in rivers of the Andean Eastern Hills of Bogotá (Colombia),

2018 ◽  
Vol 23 (2) ◽  
pp. 291-317 ◽  
Author(s):  
Alexandra Buitrago-Guacaneme ◽  
Aura Sotelo-Londoño ◽  
Gabriel A. Pinilla-Agudelo ◽  
Alexander García-García ◽  
Ligia I Moncada ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Small Rivers ◽  
Black Flies ◽  
Benthic Organisms ◽  
Running Water ◽  
Dca Ordination ◽  
Chemical Factors ◽  
Abundance And Diversity ◽  
Three Rivers ◽  
Physical And Chemical

Black flies are abundant benthic organisms in well-oxygenated running water and are considered effective bioindicators of water quality. Information on the ecology of these organisms at the species level is important, since up to now information has mainly been available on a family level. The aim of this study was to evaluate the composition of black flies and their relationships to a group of physical and chemical factors in four small rivers of the Eastern Hills around Bogotá, Colombia. These headwaters are protected by the Empresa de Acueducto y Alcantarillado de Bogotá. Black fly larvae and pupae were collected during four sampling periods during the dry season to the early rainy season of 2012. Multivariate methods were used to determine the presence of each species in relation to dissolved oxygen, nitrates, pH, temperature, and water velocity. PCA ordination revealed a physicochemical environment with a tendency towards a certain homogeneity in the fourrivers studied. The DCA ordination confirmed that in La Vieja River the G. ortizi complex dominated while S. muiscorum was dominant in the other three rivers. Similarly, according to the NMDS, the composition of black flies in Arzobispo and Chorro de Padilla rivers was similar, while that of El Delirio and La Vieja rivers were different, especially in this last river. The rivers hadlow species richness (four species and one species complex). Simulium muiscorum was negatively correlated with dissolved oxygen, temperature and current velocity while S. ignescens was associated with slightly more oxygenated waters and S. furcilatum with fastercurrents.The low species diversity and richness for the four rivers is consistent with previous report sof low Neotropical diversity of black flies. Results showed that simuliid species could possibly be good indicators of the environmental conditions of Eastern Hills rivers around Bogotá.

Modelling of dissolved oxygen content using artificial neural networks: Danube River, North Serbia, case study

2013 ◽  
Vol 20 (12) ◽  
pp. 9006-9013 ◽  
Author(s):  
Davor Antanasijević ◽  
Viktor Pocajt ◽  
Dragan Povrenović ◽  
Aleksandra Perić-Grujić ◽  
Mirjana Ristić
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Dissolved Oxygen ◽  
Oxygen Content ◽  
Danube River ◽  
Artificial Neural
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