In Taiwan, the rapid development of the petrochemical industry over the past four decades has resulted in economic progress and technological advancement. However, this success has been accompanied by pollution and sporadic accidents. Numerous accidents related to crude oil and its derivatives have resulted in a loss of life, employee injuries, environmental and property damage, economic decay, social outcry, and even political turmoil. This study investigated a caprolactam storage tank accident through root cause analysis with a computational approach. The previously described approaches returned findings that indicated causes similar to the real cause of this caprolactam accident. The four summarized descriptions of false conditions of the caprolactam explosion can serve as a reference for other investigations into the causes of petrochemical accidents. Reason of the caprolactam storage tank accident was determined by root cause analysis accompanying with a computational approach. (C) 2017 Elsevier Ltd. All rights reserved.