Risk-Based Inspection Analysis for High-Pressure Hydrogenation Cracking Unit

The high-pressure hydrogenation cracking unit is the core equipment system in the aromatic hydrocarbon factory, which is subjected simultaneously to the action of hydrogen, high pressure, and high temperature. In this paper, quantitative analysis method of risk-based inspection (RBI) was carried out with a commercially available RBI software. In API 581, the risk situation for each type of equipment in the system was classified into four grades: low-risk grade, medium-risk grade, medium-high-risk grade, and high grade. This is expressed as a risk matrix. The entire risk distribution of 553 equipment and/or piping items of the systems that compose the unit was obtained. The hydrocracking reactors and the reactor effluent air coolers are in the “medium-high-risk” category. Based on the RBI results, an optimum inspection plan was developed by the author to reduce the risk level for the hydrogenation cracking unit. Upon validation of the inspection activity in 2004, it is concluded that the optimum inspection plan was in compliance with the engineering specification of the aromatic hydrocarbon factory.