Products tagged with 'zinc sulfide'

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Picture for Corrosion Behavior of Zinc Cold Spray Coatings (ZnCr & ZnNb) in a Simulated Natural Gas Environment Containing H2O, CO2, and H2S
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Corrosion Behavior of Zinc Cold Spray Coatings (ZnCr & ZnNb) in a Simulated Natural Gas Environment Containing H2O, CO2, and H2S

Product Number: 51324-20451-SG
Author: Zineb Belarbi; Richard E. Chinn; Ömer N. Doğan
Publication Date: 2024
Internal corrosion and sulfide stress cracking (SSC) are problems for steel pipelines transporting natural gas or CO2 containing partial pressures of H2S higher than 0.3 kPa (0.05 psi). The objective of this work is to mitigate internal corrosion and SSC in steel pipelines transporting natural gas containing H2S using cold spray coatings. Two types of the cold spray binary metallic coatings (zinc chromium (ZnCr), zinc niobium (ZnNb)) were studied using electrochemical techniques: potentiodynamic polarization (PDP), linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS). The evaluation of the corrosion resistance of cold spray coatings (ZnCr, ZnNb) was carried out in an environment containing 4 bar CO2 pressure, simulating the partial pressures that are found in gas transmission lines over a solution of 3.5 wt.% NaCl heated to 40 °C. To simulate sour conditions, a concentration of 0.003 M Na2S2O3.5H2O, which corresponds to H2S partial pressures around 0.079 bar (1.146 psi), was used. Post-corrosion surface characterization was performed using a scanning electron microscope (SEM) equipped with energy-dispersive X-ray spectroscope (EDS) and X-ray diffraction analysis (XRD). The data showed that the presence of 0.003 M Na2S2O3.5H2O shifted the corrosion potential to more anodic values and decreased the corrosion current density. Bothcoatings showed similar behavior after 1 hour of exposure in CO2/H2S environment, which indicated that similar electrochemical reactions were taking place on ZnNb and ZnCr. SEM images and EDS surface analyses for specimens showed a significant change in surface chemical composition of carbon steel coated with ZnNb and ZnCr, after 24 hours of immersion. No localized attack was observed. The EDS analysis and XRD results revealed the presence of zinc sulfide (ZnS).
Picture for Critical Review on Sulphide Scale Formation, Removal and Inhibition
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Critical Review on Sulphide Scale Formation, Removal and Inhibition

Product Number: 51320-14731-SG
Author: Bader Al-Harbi, Norah Aljeaban, Alexander Graham, Ken Sorbie
Publication Date: 2020

Sulphide scales, namely iron sulphide (FeS), zinc sulphide (ZnS) and lead sulphide (PbS), are increasingly being encountered in gas/oil wells. These scales can present serious safety concerns, impair well productivity and limit access to downhole tools. There are many published research studies addressing sulphide scale removal and inhibition. However, there is an incomplete understanding of the governing processes of sulphide scale formation and prevention. Furthermore, there are contradictory results in the literature on issues such as the removal procedures and inhibition tests for sulphide scales. Therefore, the main objective of this paper is to critically review the published work on sulphide scale formation, removal and inhibition, to address the factors that control them and to discuss some of the apparent discrepancies in published experimental studies.
The review discusses the formation mechanisms of different sulphide scales in relation to the sources and levels of Fe, Zn, Pb and the sulphide species. The experimental procedures used by different researchers to evaluate sulphide scale dissolvers and inhibitors are described, along with the performance results for the chemistries tested to remove or prevent sulphide scales.
Hydrochloric acid has been shown to outperform rival chemistries for dissolving sulphide scales, however the associated high corrosion rate and H2S generation has necessitated the development of other dissolvers to overcome such drawbacks. Several dissolvers based on chelating agent chemistries combined with catalysts provided high dissolution rates, and the dissolution results and the reaction mechanisms will be discussed in some detail.

Multiple factors have been shown to play a significant role in the inhibition efficiency of sulphide scale inhibitors including pH, salinity, temperature, scale formation sequence and mechanism, and the initial concentrations of sulphide species and scaling metals. In addition, there is a developing understanding of the significance of scale inhibitor consumption in these systems.
Understanding the formation mechanism is essential for accurate interpretation of scale-related issues in the field and for providing the correct treatment strategy. A more complete knowledge of these issues will lead to the further development of reliable procedures for generating dissolution and inhibition results and consequently improving the scale dissolver and inhibitor chemistries themselves.

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Metal Sulfide Scale Inhibitors

Product Number: 51320-14459-SG
Author: Konstantinos D. Demadis, Argyro Spinthaki, George Petratos, Juergen Matheis, Duygu Disci-Zayed, Wolfgang Hater
Publication Date: 2020