Ancor Pipeline Integrity

During the evaluation process, nine (9) cleaning were conducted with different tools configurations and performed an in-line inspection using an Ultrasonic (UT) tool. Based on the results from the In-Line inspection, the following was concluded:

The corrosion feature was assessed in terms of their axial and circumferential dimensions using Original B31.G Assessment and Kastner respectively and were considered acceptable for operation (PSafe > MAOP).

Geometry anomalies (dents) were reported, and the following was indicated:

The pipe wall deformations associated with seven (7) dents with distance less than minimum distance between adjacent dents allowed (distance < 2×Lmsd) confirm an interaction from each other and thus affect their fatigue lives. In addition, all of them were associated with possible mechanical damage and based on the ASME B31.8, ASME B31.8S, ASME B31.12 and API 1160, a dent containing mechanical damage (stress riser or stress concentrator) are not allowed and must be repaired.
Three (3) dents had a distance more than minimum distance between adjacent dents allowed (distance > 2×Lmsd) and there was no interaction with other dents. However, none of them were acceptable due to the strain levels exceed the ASME requirements (Strain levels > 6%) and they were associated with laminations, and could represent a risk to the pipeline integrity, that can promote propagation of possible crack-like defects and must be repaired.
The rest of the geometry anomalies were assessed as plain dents and was determined acceptable for operation (MAWP > MAOP).

Lamination features were reported, and the following was indicated:

a) A few laminations were associated with dents and were considered to pose a threat to the pipeline integrity due to stress concentration that can promote propagation of possible crack-like defects and thus must be repaired.

b) In addition, a few lamination features were located in the HAZ of welds. None of them meet the API 579 Level 2 Assessment requirements, based on the condition of the distance between the edge of the lamination and the nearest weld, and they were considered to pose a threat to the pipeline integrity due to stress concentration that can promote propagation of possible crack-like defects and thus must be repaired.

c) The rest of lamination features met all the Level 2 Assessment requirements, and they were acceptable for operation (MAWP > MAOP).

4. The corrosion growth rate was obtained considering this was the first in-line inspection after the last known inspection and it was used as baseline. A probabilistic assessment was performed, using Monte Carlo simulation with distribution of depth and corrosion starting time, according to indicated by API 1160 with an 80% confidence level, and the internal and external corrosion growth rates were identified. Normal Fitted Distribution of external corrosion growth rate:

5. An optimum re-inspection interval was developed, based on the remaining life of uninvestigated corrosion defects, provided that the operating conditions and mitigation activities against the corrosion growth are maintained.

Based on the above findings, ANCOR recommended repair activities as it's indicated below:

eliminate all anomalies to pose a threat to the pipeline integrity, using one of the methods below (based on each features condition):

- Replacement

- Install full encirclement sleeve Type B

Note: All recommendation included GPS Coordinates, begin distance of the repair activity (considering the upstream girth weld as reference) and total length of the recommendation.

Additional mitigation activities were recommended such as:

- keep the CP system condition on the pipeline and perform annual CP surveys to support the continuous operation of the cathodic protection system and establish historical records and compliance.

- Carry out internal cleaning at least once a year, to avoid sediments accumulation than can contribute with the formation and growth of internal corrosion processes and adjust the execution time based on the results obtained if necessary.

Finally, the re-inspection interval was recommended, considering the assessment developed.

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