安全完整性要求的分配-基本原理

[中文适用范围]： 本文件可用于已根据 ISO 12100 对机器或过程设备进行了风险评估，并已选定安全相关控制功能作为针对特定危害的防护措施的场合。本文件描述了将安全完整性要求分配给所选定功能的一个基本逻辑示例。描述是通用的，尽可能独立于可用于分配安全完整性要求的任何特定工具或方法。该要求可以表示为安全完整性等级 (SIL) 或性能等级 (PL)。所描述的基本逻辑示例体现在遵循基于风险的定量方法的方法和工具中。反之，本文件中描述的逻辑可用作评估特定安全完整性分配方法或工具的参考。这可以阐明相应工具/方法在多大程度上遵循基于风险的定量方法，以及在何处由于其他考虑因素而偏离该方法。在实际应用中，基于风险的定量方法在许多情况下出于正当理由可能会受到其他考虑因素的修改或覆盖。讨论或评估这些理由不在本文件的范围内。通常，偏离给定工具或方法的基于定量逻辑的理由会被提供，以便在适当的框架内进行讨论。提供了常见分配工具（以风险图和风险矩阵格式）的此类分析示例。本文件可用于所有应用模式下的安全相关控制功能：连续模式、高需求模式和低需求模式应用。 [外文原描述]： IEC TR 63161:2022 can be used where a risk assessment according to ISO 12100 has been conducted for a machine or process plant and where a safety related control function has been selected for implementation as a protective measure against specified hazards. This document describes an example basic logical rationale to assign a safety integrity requirement to the selected function. The description is generic and as far as reasonably possible independent from any specific tool or method that can be used for assignment of a safety integrity requirement. The requirement can be expressed as a safety integrity level (SIL), or performance level (PL). An example basic rationale is described that is embodied by such methods and tools, as far as they follow a risk based quantitative approach. Conversely, the logic described in this document can be used as a reference for assessing specific methods or tools for safety integrity assignment. This can clarify how far the respective tool/method is following a risk based quantitative approach, and where deviations from that approach are imposed by other considerations. In real applications, the quantitative risk based approach can be modified or overridden by other considerations in many cases and for good reasons. It is not within the scope of this document to discuss or evaluate such reasons. Usually the reasons for deviations from a given tool or method from a quantitative logic are provided, so that this can be discussed in the proper frame. Examples for such analyses are provided for common assignment tools in the format of risk graphs and risk matrices. This document can be used for safety related control functions in all modes of application: continuous mode, high demand mode and low demand mode of application.