Risk Assessment in Dropped and Drag Anchor in Offshore Pipeline Based on DNV RP F107 and DNV RP F111

This research conducts risk assessment towards the offshore pipeline against one of the potential hazards which can occur, namely the incident of dropped and dragged anchors. The method applied in this study involves assessment using the standard code DNV RP F107 and DNV RP F111. The main parameters involve in the study to generate the level of risk include the frequency of occurrence and the amount of energy from the dropped and dragged anchor. The output of the assessment is reflected in the risk matrix. Two types of pipelines were used, namely pipeline A with outer diameter of 150 mm wall thickness of 12.5 mm, and pipeline B with outer diameter of 219 mm and wall thickness of 7.95 mm, are studied against two different anchors’ weight. The weight of the anchor is 1,590 kg and 2,870 kg, respectively. The analysis towards the frequency of dropped and dragged anchor and the amount of energy from dropped and dragged anchored has been performed for both types of pipeline. This research showed that both pipelines possessed a medium risk level for dropped and dragged anchors. The recommendation for the risk mitigation plan would be to provide concrete coating with thickness of 50 mm and 60 mm for 1,590 kg anchor and to provide 80 mm concrete coating for 2,870 kg anchor, resulting in the decrease of risk level to lower risk category.