Damage Mechanism Study of Severe Corrosion of Carbon Steel Pipe in SAGD Brackish Water Service
Bibliographic record
Abstract
Abstract The carbon steel lines carrying brackish water associated with a heavy oil SAGD (Steam Assisted Gravity Drainage) operation in Northern Alberta experienced severe localized corrosion attack specific to bends, welds, and other locations containing a gas phase. Pinhole leaks occurred after only seven years of service. A comprehensive study was conducted which included consideration of possible damage mechanisms based on flow regime, water chemistry, gas composition, piping elevation changes, and various corrosion product/material analysis. This paper is a continuation of a previous study3 which was based on similar failures which occurred at similar facility. New findings are discussed regarding how the pipes are damaged. It is concluded that CO2 breakout is the major cause of severe pitting on the bends and preferential weld attack despite a low CO2 concentration of < 30 mg/L in the water. The CO2 breakout under turbulent flow and/or piping elevation changes resulted in corrosion rates up to 1.125 mm/y (45 mpy) at 10 °C. In comparison, the De Waard-Milliams model predicted a corrosion rate of only 0.0425 mm/y (1.7 mpy)! Turbulent flow (Reynolds number is 1.7x105) and depressurization contributed to the CO2 breakout from the water which caused severe corrosion with the protective siderite readily removed. Corrosion occurring at CO2 gas/water/metal boundaries resulted in high pitting rates and corrosion was aggravated with the increase in mass transfer when gas bubbles collapse. Oxygen corrosion and microbial induced corrosion as secondary damage mechanisms are also discussed in this paper. The corrosion damage mechanism study provides guidance for BW piping/pipeline designs and material selection.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".