Abstract Risk-based inspection (RBI) offers the most cost-effective operation and maintenance strategy for minimizing overall risks and making financial and safety improvements within a power plant. Risk assessment may also benefit decision-making with regards to plant design and equipment manufacturing processes. The purpose of this study is to propose a quantitative RBI methodology that can be applied to a high-energy piping system operating at elevated temperatures and high pressures in power plants. Three major steps involved are: (i) using generic mean time to failure (MTTF), specified as the expected lifetime of the equipment obtained from a theoretical equation; (ii) adding a modification factor that identifies the specific conditions that can influence the failure rate; and (iii) incorporating individual inspection locations as a factor in risk evaluation. Probability-of-failure (POF) assessment was conducted using a Weibull distribution with MTTF and the modification factor. In addition, consequence-of-failure (COF) assessment was conducted based on financial consequences in terms of downtime costs per day and the length of downtime due to failure. The main steam piping system in a thermal power plant was selected as the case study unit. The actual inspection locations where damage to components could frequently occur were defined as risk evaluation targets for the RBI. The generic MTTF for the main steam piping system was evaluated using the Larson-Miller parameter (LMP) equation for creep rupture time. Piping system stress analysis was conducted to obtain the stress applied to the LMP. An equation for the modification factor applied to the main steam piping system was also proposed based on five subfactors.

中文翻译：

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使用概率分布函数和修正因子的高能管道定量风险检测方法

摘要 基于风险的检查 (RBI) 提供了最具成本效益的运行和维护策略，可最大限度地降低发电厂的整体风险并改善财务和安全。风险评估也可能有益于工厂设计和设备制造过程的决策。本研究的目的是提出一种定量 RBI 方法，该方法可应用于发电厂中在高温和高压下运行的高能管道系统。涉及的三个主要步骤是： (i) 使用通用平均故障时间 (MTTF)，指定为从理论方程获得的设备的预期寿命；(ii) 添加一个修正系数，以识别可能影响失效率的特定条件；(iii) 将个别检查地点作为风险评估的一个因素。使用具有 MTTF 和修正因子的威布尔分布进行故障概率 (POF) 评估。此外，故障后果 (COF) 评估是根据每天停机成本和因故障导致的停机时间长度等财务后果进行的。选择某热电厂的主蒸汽管道系统作为案例研究单元。可能经常发生组件损坏的实际检查位置被定义为 RBI 的风险评估目标。使用 Larson-Miller 参数 (LMP) 方程计算蠕变破裂时间，对主蒸汽管道系统的通用 MTTF 进行评估。进行管道系统应力分析以获得施加到 LMP 的应力。