Mechanical Properties of a Mackinawite Corrosion Product Layer

To investigate the magnitude of stress required to damage iron sulfide layers up to the point of exposing the substrate, well-defined iron sulfide layers were developed in a 4-liter glass cell and the mechanical properties of the layers, such as hardness and adhesive strength, were investigated usin...

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Bibliographic Details
Published inNACE International Corrosion Conference Proceedings pp. 1 - 16
Main Authors Anyanwu, Ezechukwu, Prieto, Claudia, Brown, Bruce, Singer, Marc
Format Conference Proceeding
LanguageEnglish
Published Houston NACE International 01.01.2019
Subjects
Adhesion tests
Adhesive strength
Adhesives
Atomic force microscopy
Cavitation
Corrosion
Corrosion products
Glass
Hardness
Interfacial shear strength
Iron carbonate
Iron sulfides
Load
Mass transfer
Mechanical properties
Research methodology
Shear flow
Shear forces
Shear strength
Substrates
Wall shear stresses
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Summary:To investigate the magnitude of stress required to damage iron sulfide layers up to the point of exposing the substrate, well-defined iron sulfide layers were developed in a 4-liter glass cell and the mechanical properties of the layers, such as hardness and adhesive strength, were investigated using a mechanical tester. While the interfacial shear strength of this mackinawite layer was found to be 5 magnitudes higher than the maximum flow related shear stress typically encountered in oil and gas operations, the integrity may still be compromised if these layers are subjected to other mechanical impacts (cavitation, droplet impingement) that may occur during production. Another method used atomic force microscopy to apply a shear force of the order of nanonewtons on an individual iron carbonate crystal with the intent to cause full detachment.5 The reported shear stress required to remove iron carbonate layer in both cases was of the order of 106 Pa, which is 3 orders of magnitude higher than the maximum flow related wall shear stress typically encountered in a multiphase pipe flow6. Experimental Method Iron Sulfide Layer Development Iron sulfide layers were developed in a 4-liter glass cell, under controlled chemistry and mass transfer conditions and the mechanical properties of the layers, such as hardness and adhesive strength, were investigated using a mechanical tester.