FTA analysis for river-traversing oil pipeline

The particularity of river-traversing oil pipeline in the process of design, construction and maintenance is always ignored in the integrity assessment of the total pipeline. The pipeline tends to be wrecked, eroded or misoperated by the third party. Once the pipeline is naked or half-hanged, it can be easily dragged by anchors or impact by river current. While the whorl-aroused vibration caused by the over-permitted stride of the hanging pipeline can finally leads to the failure. The special FTA model is established, in which the failure probability, the probability and the danger importance degree of the basic event are calculated. Analyzing the failure model of the leaked or ruptured traversing pipeline in qualitative and quantitative pattern, 22 minimal cut sets of 1st rank, one of 2nd rank and 39 of 3rd rank are acquired The calculation shows that: the total failure probability of the traversing pipeline is 3.791 55 times 10^-3. The influence factors can be sorted with danger level from high to low as follow: bareness or hanging, wrecking by the third party, misoperation, erosion and defects. Since the FTA analyzing results of the traversing pipeline and common pipeline are sharply different, the traversing pipeline should be assessed individually in the integrity assessment of pipeline corporations.