Gases and chemical materials have been transferred by underground pipelines in petrochemical complexes. In Ulsan petrochemical complex, the largest one in Korea, the underground pipelines are laid since 1962, thus the oldest ones are superannuated more than 50 years. Moreover, the pipes have been rusted by soil. These deterioration and corrosion increase the possibility of accidents. In Kaohsiung, Taiwan, 20 years old underground propylene pipeline exploded causing 32 deaths and 321 injuries, last year. To prevent these accidents, the effects of deterioration and corrosion in underground pipelines should be studied quantitatively.
In this study, quantitative risk of underground propylene pipeline is analyzed according to deterioration and corrosion. The actual Ulsan petrochemical complex‘s information, such as geometry, population and weather, are used to calculate the risk. First, indirect assessment, such as CIPS (Close Interval Potential Survey) and DCVG (Direct Current Voltage Survey), and direct assessment are carried out to find out actual state of the pipelines. Second, accident frequencies are computed reflecting direct and indirect assessment by referring to OGP (Oil and Gas Producer) data. Then, consequences of underground propylene release are simulated in Phast v6.7. Next, release cases of new pipeline and old one are compared. As a result, adequate replacement schedule of the pipeline to reduce the risk is suggested. This research would contribute to the risk reduction in the underground pipeline explosions.