Catodic Shielding In Gas Pipelines

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Asadi Moshizi, Reza | 2012

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Type of Document: M.Sc. Thesis
Language: English
Document No: 43066 (57)
University: Sharif University of Technology, International Campus, Kish Island
Department: Science and Engineering
Advisor(s): Allahkaram, Saeed Reza
Abstract:
It is very important to determine why there is still external corrosion on pipelines even though NACE RP0169 criteria are satisfied. The cathodic shielding problem is the most relevant finding to this kind of situation. In this research, the shielding behavior of three types of coatings (FBE, 3LPE and Polyurethane) used in Iranian gas industries are evaluated under laboratory condition by four major procedures. It has been found out that the FBE coating has no shielding effect and instead 3LPE coating has a shielding effect by not allowing electrical conductivity through the coating. Finally, the Polyurethane coating presented a mid-behavior effect but almost near to non-shielding behavior. On the other hand, cathodic disbondment tests showed the high tendency of Polyurethane to water uptake and as a result more amounts of disbondment occurred as compared to FBE and 3LPE coatings and it was understood that there was no defined correlation between the amount of water uptake and shielding behavior
Keywords:
Cathodic Disbonding ; Gas Pipelines ; Electrical Impedance ; Cathodic Shielding

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