Volume 12, Issue 43 (5-2022)
مهندسی خوردگی 2022, 12(43): 75-87 |
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Evaluation of Underground Gas
Pipeline External Corrosion Due to AC
and DC Interference Currents. مهندسی خوردگی 2022; 12 (43) :75-87
URL: http://journal.ica.ir/article-1-177-en.html
URL: http://journal.ica.ir/article-1-177-en.html
Abstract: (391 Views)
Adjunct to underground railway (which produce DC interference currents) and overhead power transmission lines
(which produce AC interference currents), underground gas pipelines have been affected severely which have
brought about corrosion costs namely direct and indirect costs. The effects of both types of stray currents on the
UG gas pipelines located in a street in Tehran are studied. On-site inspections were performed and then additional
laboratory studies were done to analyze and characterize the corrosion products. It is founded that the coating of
the pipe has been disbonded in two points which are in 10-meter distances from each other and the external pipe
wall were locally corroded which has led to gas leakage. According to the standard criteria and the results of AC
potential, AC interference current may not cause the corrosion in the points. However, the amounts of off-
potentials were out of range according to the relevant standards and therefore DC stray current produced by
Tehran underground railway has mainly led to the corrosion. Corrosion products were not uniformly covered the
metal surface and mainly contains Fe3O4 and FeOOH as well as FeCl2. Thus, it is recommended that additional
evaluations need to be done according to BS EN 50162 and afterwards, protective measures must be taken to
eliminate the side effects of the DC stray current.
(which produce AC interference currents), underground gas pipelines have been affected severely which have
brought about corrosion costs namely direct and indirect costs. The effects of both types of stray currents on the
UG gas pipelines located in a street in Tehran are studied. On-site inspections were performed and then additional
laboratory studies were done to analyze and characterize the corrosion products. It is founded that the coating of
the pipe has been disbonded in two points which are in 10-meter distances from each other and the external pipe
wall were locally corroded which has led to gas leakage. According to the standard criteria and the results of AC
potential, AC interference current may not cause the corrosion in the points. However, the amounts of off-
potentials were out of range according to the relevant standards and therefore DC stray current produced by
Tehran underground railway has mainly led to the corrosion. Corrosion products were not uniformly covered the
metal surface and mainly contains Fe3O4 and FeOOH as well as FeCl2. Thus, it is recommended that additional
evaluations need to be done according to BS EN 50162 and afterwards, protective measures must be taken to
eliminate the side effects of the DC stray current.
Keywords: Underground Gas Pipelines, Underground Railways, Overhead Power Transmission Power lines, AC
& DC Corrosion
Type of Study: Research |
Subject:
General
Received: 2023/01/28 | Accepted: 2023/01/30 | Published: 2023/01/30
Received: 2023/01/28 | Accepted: 2023/01/30 | Published: 2023/01/30
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