Risk assessment of ships collision during installation of anode protection on subsea gas pipeline located in Surabaya West Access Channel

Subsea pipeline is one of alternatives to transport gas from offshore platform to onshore production facility. In Surabaya West Access Channel (APBS), there are some subsea gas pipelines lay on seabed. Maintenance of subsea pipeline should be carried out to ensure the sustainability of gas delivery, such as replacement of Sacrificial Anode Cathodic Protection. Since the replacement activity includes operation of Diving Support Vessel (DSV) along the subsea pipeline, it could potentially induce ship collision between DSV with other ships passing through the channel. This paper carried out a risk assessment of ship collision during replacement of anodes of subsea gas pipeline in APBS. The frequency of ship collision is analyzed by using Computerized Risk Assessment of Shipping Hazards (CRASH) and Traffic Based Models. The consequence is analyzed using Finite Element Method (FEM) which results the impact of collision on the hull of ship. Deformation of hull requires cost of repair which further becomes the outcome of consequences analysis. The risk is represented in the risk matrix which adopted from the Australian Standard Guidelines. The result shows that frequency of collision is 0.1342 per year while the consequences analysis results US$ 2,160,077 which required for repair. The risk representation shows that the anodes replacement has an extreme risk level based on the Australian Standard Guidelines. Further preventive measures are required to reduce the level of risk to be medium or low level of risk.