STAMP-STPA based forward model construction of typical LNG repository accidents

Abstract:

In the absence of relevant accident probability statistics, in order to improve the overall safety of the Liquefied  
Natural Gas (LNG) system, we need to solve the problems that traditional safety analysis methods cannot consider. These are the  
internal correlation of complex systems, component interaction and macro control. The analysis ideas are scattered and we need  
to ensure the accuracy of the forward results of stratification, rollover and fire accident of LNG repositories, A STAMP-STPA  
(Systems-Theoretic Accident Model and Processes)- (Systems-Theoretic Process Analysis) based a forward model of typical  
LNG repository accidents was established, making the follow-up system of unexpected trouble analysis and accident cause  
analysis better and more comprehensive. First, according to the equipment and facilities, process and their correlation with each  
other involved in stratification and rollover accidents and fire accidents of LNG storage tanks, a preliminary risk analysis of  
the accidents was carried out, and then the factors leading to the accidents were identified, and the key nodes of the risk were  
ascertained. On this basis, the safety requirements and safety constraints of the accident system were analyzed, including control  
and feedback operations that may lead to accidents. A STAMP model was established which included the control and feedback  
relationships among the relevant facilities, components, and control feedback loops. Second, the STPA method was adopted  
to identify four unsafe control behaviors in the LNG safeguard process (including failure to provide control behavior, error or  
unsafe supply control behavior, failure to provide control behavior in a timely manner, and premature end of control behavior),  
and analyze the initial value (such as tank LTD parameter), current state (such as infusion operation) and state transition (such  
as tank and cooling completion preparation) involved in the overall process of the accident from two aspects of insufficient  
execution of control behavior, feedback error or insufficiency, and then understand the key causes of unsafe control behaviors,  
and established the complete forward model of typical accidents in LNG storage tanks. Finally, combined with specific accident  
cases to verify and analyze the effectiveness and practicality of the typical accident forward model of the LNG storage tank,  
and visualize the analysis results in the form of knowledge graphs. The study shows that the model can systematically analyze  
typical LNG accident processes of LNG tanks in complex systems from the perspective of control and constraints, which makes  
the accident evolution process more intuitive and the reasons for unsafe control behaviors clearer; and fully considers the causal  
relationship of various risk factors in the stratification, rollover and fire accidents forward from the system perspective, thus  
providing feasible and effective value information for the subsequent safety management of LNG storage tanks.


Key words:LNG repository; unsafe behavior; STAMP-STPA; fire accident; stratification and rollover accident

Received: 2020-06-25

Corresponding Authors: hujq@cup.edu.cn.

Cite this article:胡瑾秋, 董绍华, 王融涵, 张曦月. 基于STAMP—STPA的LNG储备库典型事故正演模型构建. 石油科学通报, 2021, 03: 481-493 HU Jinqiu, DONG Shaohua, WANG Ronghan, ZHANG Xiyue. STAMP-STPA based forward model construction of typical LNG repository accidents. Petroleum Science Bulletin, 2021, 03: 481-493.

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