Top of line corrosion (TLC) has been studied for several decades however, carry-over of hungry water (freshly condensed, devoid of dissolved corrosion products) from a Corrosion Resistant Alloy (CRA) or CRA clad section to a carbon steel (CS) section of a pipeline, which could produce additional corrosion downstream the CRA-CS transition, has not been thoroughly addressed. This has resulted in conservative assumptions of the “hungry water effects” on TLC. Thus, a bespoke experimental approach has been developed to study this “hungry water” phenomenon. Special specimen racks housing alternating CS and CRA tubular segments with minimal separation were adapted to a TLC flow loop to achieve the desired condensation rates. The TLC rates were evaluated from dissolved Fe2+ (collected condensed water) and trapped Fe2+ (precipitated FeCO3). Cutting the CS segments into several rings revealed the variation of the trapped-iron corrosion rate as a function of position relative to the CRA/CS transition and effects associated with such transitions.

The experimental approach and the computerized image analysis routine developed in this work are proven to be useful tools capable of producing valuable data both on pipeline design (on a case-by-case basis) and in support of model development.

Subject
Scanning electron microscopy, Water, Corrosion rate, Top of the line corrosion, Condensation, Pipelines, Iron, Condensation rates, Liquids, Corrosion products, Layer thickness, Glycol, Carbon steel
Keywords:
CO2 corrosion, Top of line corrosion, Hungry water carryover
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2025
Association for Materials Protection and Performance (AMPP)
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