Premature Failure of Ni-coated Carbon Steel Fittings in Water Injection Service Due to Microbiologically Induced Corrosion
Bibliographic record
Abstract
Abstract This paper presents the findings of an investigation that was carried out to determine the root cause of the premature failure of Ni-coated carbon steel fittings on the water injection composite piping system installed at an oil production facility in Western Canada. The facility had been in operation since 2011 without major corrosion issues. Many of the Ni-coated fittings, which are expected to have a service life of 20 years, started to fail (developed leaks) unexpectedly after about 4 years. The core structure of composite pipe is a high-density polyethylene (HDPE) inner pipe, a middle layer of high-strength dry fiberglass, and a protective thermoplastic outer jacket. The interconnecting fittings are made of carbon steel coated with a thin, ~40 micron (1.5 mil) layer of Nickel. The failure investigation results (bacteria, water, and corrosion product analyses as well as photographic documentation of the corrosion damage morphology) provided quite convincing evidence that the premature failures observed in the fittings occurred as a result of MIC (microbiologically influenced corrosion) due to the presence of high counts of SRB (sulfate reducing bacteria) and APB (acid producing bacteria) in the system. Of course, under-deposit corrosion, crevice type corrosion, and galvanic corrosion may also have occurred in conjunction with MIC. It is also to be noted that if the integrity of the thin Ni coating is compromised in any way, such as pitting damage due to MIC, or manufacturing flaws, accelerated galvanic corrosion attack of the carbon steel substrate would be expected at that location, since Ni is cathodic to carbon steel.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 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".