Bulletin of the Society of Sea Water Science, Japan
Online ISSN : 2185-9213
Print ISSN : 0369-4550
ISSN-L : 0369-4550
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Volume 61, Issue 3
Displaying 1-7 of 7 articles from this issue
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  • Corrosion Resistance of Salt Production Apparatus and the Problem
    Fumihiko YAMADA, Michio HIDAKA, Taisuke KANEKO, Tateru FUKUMOTO
    2007 Volume 61 Issue 3 Pages 141-148
    Published: 2007
    Released on J-STAGE: February 19, 2013
    DOIhttps://doi.org/10.11457/swsj1965.61.141
    JOURNAL FREE ACCESS
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  • Instance of Defect Assessment and Corrosion Countermeasure in Salt Product Plant
    Takeo KAWABATA
    2007 Volume 61 Issue 3 Pages 149-154
    Published: 2007
    Released on J-STAGE: February 19, 2013
    DOIhttps://doi.org/10.11457/swsj1965.61.149
    JOURNAL FREE ACCESS
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  • Monitoring of Localized Corrosion Progression Utilizing Acoustic Emission (AE)
    Hideo CHO, Takuma MATSUO, Misako KONDO, Mikio TAKEMOTO
    2007 Volume 61 Issue 3 Pages 155-158
    Published: 2007
    Released on J-STAGE: February 19, 2013
    DOIhttps://doi.org/10.11457/swsj1965.61.155
    JOURNAL FREE ACCESS
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    Acoustic Emission (AE) technique becomes a useful tool to monitor local corrosions. It utilizes AEs produced by fracture of corrosion product (rust) and hydrogen gas evolution. In case of SCC associated with pitting corrosion of Type-304 stainless steel in concentrated chloride solution, AEs were produced by the oxide fracture in the pits prior to the SCC initiation. Detected AEs could be classified into two types (Type-I and-II) by their frequency characteristic. Type-II with low frequency components less than 0.2 MHz was found to be produced by the rust fracture while the Type-I by the mechanical fall-off of grains. Crevice corrosion test of flange-connected Type 304 steel pipe in 3 and 20 mass% NaCL solutions at controlled potentials produced frequent AEs. Generation rate of the AE was found to be proportional to the anodic current or the progression rate of the crevice corrosion. A new AE system utilizing telecommunication optical fiber was demonstrated to detect AEs from the rust fracture and expected to be a low-cost monitoring system applicable to large process equipments.
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  • Electrochemical Noise Analysis for Predicting the Initiation of Localized Corrosion
    Hiroyuki INOUE
    2007 Volume 61 Issue 3 Pages 159-161
    Published: 2007
    Released on J-STAGE: February 19, 2013
    DOIhttps://doi.org/10.11457/swsj1965.61.159
    JOURNAL FREE ACCESS
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    Recently, the electrochemical noise analysis is received attention as a corrosion monitoring technique for chemical plants, including salt production facilities. In this article, a concept of electrochemical noise analysis as an approach for predicting the generation of localized corrosion was briefly reviewed. The electrochemical noise is a transient current or a potential fluctuation generated by the current. The transient current is generated with an initiation-repassivation cycle of metastable pits or small cracks. A generation mechanisms of the transient current, a method for measuring the electrochemical noise, and a way to monitor the risk of developing pitting and stress corrosion cracking from the analytical results were described.
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  • Influencing Factors on Galvanic Corrosion
    Hitoshi YASHIRO
    2007 Volume 61 Issue 3 Pages 162-164
    Published: 2007
    Released on J-STAGE: February 19, 2013
    DOIhttps://doi.org/10.11457/swsj1965.61.162
    JOURNAL FREE ACCESS
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    The influencing factors on galvanic corrosion were reviewed briefly on the basis of an electrochemical equivalent circuit. Electrochemical circuit is formed when two different metals immersed in a common electrolyte come into electric contact. Anodic current density on a less noble metal (anode) is a function of potential difference, apparent anodic polarization resistance, apparent cathodic polarization resistance, solution resistance, contact resistance, anode area and its ratio to cathode area. Galvanic corrosion can be prevented by keeping at least one of these resistance values higher that 105Ωcm2, preferably of contact resistance. Smaller cathode area is recommended while smaller anode area should be avoided.
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  • Prevention of Crevice Corrosion by Infiltrating Pure Water
    Akio NAKAMURA, Hiroyuki INOUE
    2007 Volume 61 Issue 3 Pages 165-168
    Published: 2007
    Released on J-STAGE: February 19, 2013
    DOIhttps://doi.org/10.11457/swsj1965.61.165
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    Crevice corrosion occurs when the concentration of chloride or hydrogen ions in the solution inside the crevice exceeds the critical levels at which the passive metal begins to be depassivated. Therefore, if pure-water is injected into a crevice through a permeable gasket, their concentration might be kept below the critical levels. In this study, the applicability of this pure-water infiltration method to preventing crevice corrosion of flanges in salt production plants was investigated. The crevice-corrosion susceptibility of a type-316 specimen with about 10 mm of effective crevice length was evaluated from the repassivation potential for crevice corrosion (ER, CREV). A paper-filter disk was inserted as the permeable gasket in the crevice. A simulated concentrated brine at 70°C was used for the test solution-The ER, CREV when the pure-water was injected was 80 mV nobler than that measured without the infiltration. The 80 mV shift of the ER, CREV to the noble direction is the equivalent of making the solution's pH increase by 1.2, theoretically. This result suggests that crevice corrosion can be prevented effectively by applying the pure-water infiltration method.
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  • The Dependence to the Pitting Potential of Stainless Steel was Affected by a Solution's Chloride-ion Concentration, pH and Temperature in Concentrated Chloride Solution
    Akio NAKAMURA, Hiroyuki INOUE
    2007 Volume 61 Issue 3 Pages 169-174
    Published: 2007
    Released on J-STAGE: February 19, 2013
    DOIhttps://doi.org/10.11457/swsj1965.61.169
    JOURNAL FREE ACCESS
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    The pitting potentials of type 316 stainless steel (SUS316) were measured in solutions whose composition simulated typical brine, concentrated brine and mother liquor in salt production. By comparing the pitting potential measured under the various conditions, we assessed how the susceptibility of the stainless steel to pitting corrosion was affected by a solution's chloride-ion concentration, pH and temperature.
    Within the near-neutral pH region, the pitting potential scarcely depended on the solution's pH. However, in the higher pH region, the pitting potential markedly increased with pH when it exceeded a critical level that was determined by the combination of the environmental factors. The pitting potentials as measured by a potential scan method, V'C100 and the intensities of each environmental factor showed the following relation within the solution's composition used in this study;
    V'C100=-0.218log (Cl-) +535/T+0.0224pH-1.48
    Cl-, T and pH designate the chloride ion concentration in molality (mol/kg-H2O), the temperature (K) and the pH value of the solution, respectively.
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