An internal corrosion assessment methodology for gas transmission systems was developed and is termed "Internal Corrosion Direct Assessment" (ICDA). The basis behind ICDA is that detailed examination of locations along a pipeline where an electrolyte such as water would first accumulate provides information about the remaining length of pipe. The primary goal of the approach is to determine if internal corrosion is likely or unlikely to exist in a chosen length of pipe. Locations most likely to accumulate electrolyte are predicted using the results of pipeline multi-phase flow modeling. If the locations along a length of pipe most likely to accumulate electrolyte have not corroded, then other locations less likely to accumulate electrolyte may be considered free from corrosion and not require further examination. The ICDA method as described in this report can be used to focus the assessment of internal corrosion in pipelines and help ensure pipeline integrity. The method is applicable for gas transmission lines that normally carry dry gas but may suffer from short term upsets of wet gas or liquid water (or other electrolyte). Includes spreadsheet model to assist in calculating the critical angle for water holdup in multiphase flow modeling
Spreadsheet model is compatible with Excel 2013 on Windows 7 64-bit machines. May work on other Windows operating systems and older versions of Excel, but has not been tested.