When learning how to write, school-age children are often told, “Do not write in the margins.” This guidance is important because it instills in a child the sense of where text is best placed on a piece of paper. The same is true for chemical processes—normal operating limits define the area where a process is best operated. However, processes may occasionally stray into the margins beyond the operating limits. As a result, facilities may need to define safety margins where temporary operation beyond the normal operating limits is tolerable. In this paper, guidance will be provided for understanding and setting operating limits and safety margins for chemical processes. Good practices from the industry for defining and setting limits, as well as documenting and communicating the limits to operational staff, will be discussed. Last, a case study that examines safe operating limits, alarm setpoints, interlocks, and process safety information for a dryer processing a thermally unstable material will be presented to illustrate the concepts of the paper.

中文翻译：

---

在空白处书写：安全操作限制的注意事项

在学习如何写作时，学龄儿童经常被告知“不要在空白处写字”。这个指导很重要，因为它可以让孩子了解文本最好放在纸上的什么位置。化学过程也是如此——正常操作限制定义了最佳操作过程的区域。但是，过程有时可能会偏离操作限制的边缘。因此，设施可能需要定义安全裕度，其中临时操作超出正常操作限制是可以容忍的。在本文中，将为理解和设置化学过程的操作限制和安全裕度提供指导。将讨论行业用于定义和设置限制以及记录限制并将限制传达给操作人员的良好做法。最后的，