Selection of Pipeline Flow and Internal Corrosion Models
|Publication Date:||1 January 2015|
Oil and gas pipelines suffer internal corrosion in locations where water is in contact with the internal surfaces of steel pipelines. NACE internal corrosion direct assessment (ICDA) standards SP02061, SP02082, SP01103 and SP01164 provide overall guidelines to assess internal corrosion. According to SP01135 the direct assessment (DA) methodology is one of the pipeline integrity assessment techniques for both internal and external corrosion. The DA methodology involves four basic steps: pre-assessment, indirect inspection, detailed examination, and post-assessment. In the ICDA standards, the indirect inspection step involves prediction of locations susceptible to internal corrosion using flow models and/or prioritization of overall corrosion severity at these locations using corrosion models. Most ICDA standards list several models for these purposes in their nonmandatory appendixes, and allow the user to select appropriate models at their discretion.
Flow and corrosion rate prediction models can also be used in conjunction with inline inspection (ILI) data to establish the frequency of ILI runs by predicting the anticipated metal loss. This is applicable to piggable pipelines, for which periodic inspections using ILI tools are typically implemented. The ILI tool travels along the pipeline to directly inspect the defects and imperfections. NACE Publication 351008 provides descriptions of ILI tools.
This report provides information for operators to assist in assessing the applicability of both proprietary and non-proprietary models, as well as the ability to assess the suitability of these models for a particular application