Faults due to human errors cost the petrochemical industry billions of dollars every year and can have adverse environmental consequences. Unquantified human error probabilities exist during process state transitions performed each day by process operators using standard operating procedures. Managing the risks associated with operating procedures is an essential part of managing the overall safety risk. Additional operator training and safety education cannot eliminate all such faults due to human errors; therefore, we propose an operating procedure event tree (OPET) like analysis with branches and events specifically designed to perform risk analysis on operating procedures. The OPET method adapts event trees to analyze the risk due to human error while performing operating procedures. We consider human error scenarios during the procedure and determine the likely consequences by applying dynamic simulation. The modified event tree provides an estimate of the error frequencies.

Operating procedure steps were developed, and potential operator faults were determined for two typical equipment switching procedures found in chemical plant operations. Then, dynamic simulation using Aspen HYSYS software was applied to determine the overpressure related consequences of each fault. Finally, the error frequencies resulting from those scenarios were analyzed using operating procedure event trees. We found that a typical ethylene plant gas header would overpressure with 0.6% frequency per manual dryer switch. Since dryer switches occur from every few days up to once per shift, these results suggest that dryer switching should be automated to ensure safe and environmentally friendly operation. Process dryer switching performed manually by operators opening and closing gate valves can be automated with control valves and a distributed control system. A sample distillation column was found to overpressure with 0.85% frequency per manual reflux pump switch.

人为错误造成的故障每年使石油化工行业损失数十亿美元，并且可能对环境造成不利影响。过程操作员每天使用标准操作程序执行的过程状态转换期间，存在无法量化的人为错误概率。管理与操作程序相关的风险是管理整体安全风险的重要组成部分。额外的操作员培训和安全教育不能消除由于人为错误引起的所有此类故障；因此，我们提出了一种操作过程事件树（OPET），例如带有分支和事件的分析，这些树是专门设计用于对操作过程进行风险分析的。OPET方法适用于事件树，以在执行操作程序时分析人为错误造成的风险。我们在程序中考虑人为错误情况，并通过应用动态仿真来确定可能的后果。修改后的事件树提供了错误频率的估计。

制定了操作程序步骤，并针对化工厂操作中发现的两种典型设备切换程序确定了潜在的操作员故障。然后，使用Aspen HYSYS软件进行动态仿真，以确定每个故障的超压相关后果。最后，使用操作过程事件树分析了由这些情况导致的错误频率。我们发现，典型的乙烯工厂集气管每个手动干燥器开关的超压频率为0.6％。由于干燥机的切换从每隔几天到一次轮班一次，因此这些结果表明，干燥机的切换应自动进行，以确保安全和环境友好的操作。由操作员打开和关闭闸阀手动执行的过程干燥器切换可通过控制阀和分布式控制系统实现自动化。发现每个手动回流泵开关的样品蒸馏塔超压频率为0.85％。