Owners, operators, regulatory entities and non-governmental agencies focus their attention on pipeline Integrity Management Plans (IMP) to address the safety and reliability of hydrocarbon pipelines as they cross environmentally sensitive areas as well as densely populated areas. IMP includes a base line assessment prioritizing the inspection and remediation of expected sensitive areas. Direct Assessment (DA) along with internal inspection, hydro-test and other equivalent methods to ascertain the condition of the pipeline are used as IMP assessment methodologies.

The topic to be covered in this article is Internal Direct Assessment which includes Erosional Velocity (EV) in addition to Internal Corrosion Direct Assessment (ICDA). This article utilizes the analysis of an onshore gas pipeline in the Gulf of Mexico to identify possible areas susceptible to corrosion.

Multiphase flow analysis simulates the characteristics and specific fluid behavior to determine erosional velocity and internal corrosion in pipelines. A multiphase flow simulator will be used to obtain the specific flow characteristics to evaluate EV and ICDA for the above mentioned pipeline system. Internal corrosion is analyzed both as top of the line corrosion and corrosion at the bottom of the line. In addition multiphase flow simulation provides accurate information related to fluids velocity and residence time.

The internal corrosion rate can be related to residence time of water and other electrolytes to formulate effective mitigation processes. This could serve as the basis for a mitigation program and significantly increase the useful life of a pipeline system.

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