ANALYSIS OF REMAINING FATIGUE LIFE IN CORRODED AND SPANNING OFFSHORE PIPELINE CASE STUDY: EPRO - NGL JUNCTION 14 INCH 3 PHASE PIPELINE
Pipelines that are spread across Indonesia, especially offshore pipelines, are more vulnerable than onshore pipelines due to continuous exposure to current loads and extreme environmental conditions. This vulnerability increases when the pipe is spanned, as it can cause Vortex Induced Vibration (VIV...
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| Format: | Final Project |
| Language: | Indonesia |
| Online Access: | https://digilib.itb.ac.id/gdl/view/76999 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | Pipelines that are spread across Indonesia, especially offshore pipelines, are more vulnerable than onshore pipelines due to continuous exposure to current loads and extreme environmental conditions. This vulnerability increases when the pipe is spanned, as it can cause Vortex Induced Vibration (VIV), ultimately leading to fatigue failure. Over time, the pipelines typically experience surface corrosion due to high humidity and the corrosive nature of seawater. Hence, it is crucial to study the effect of corrosion on the fatigue life of offshore pipelines.
This research was conducted to analyze pipelines experiencing spanning based on DNVGL-RP-F105. Pipelines that don’t meet the screening criteria will be modelled and analyzed to determine the remaining fatigue life. To assess the impact of corrosion on the remaining fatigue life, the S-N curve based on the Heywood Model was utilized.
From the results of the study conducted on 16 spans based on inspection of the 14-inch EPRO – NGL Junction pipeline, 1 span did not meet the screening criteria, necessitating the calculation of fatigue life. Corrosion on the pipelines causes Stress Concentration Factor of 2.838. As a result, the limit on the number of permissible stress cycles for the pipelines to operate within its design life (10 years) dropped from 1100 cycles to 400 cycles. The parametric study findings indicate a significant decrease in the pipeline’s fatigue life up to a depth of corrosion, ????????, of approximately 40%, but it tends to stabilize thereafter. Additionally, the pipe is considered unsafe, and it is recommended to implement mitigation measures when the relative span length has reached 150% of the span length recorded during the 2009 inspection.
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