Where can you find all the valves that require locking devices listed?

The correct answer identifies the EO's Standing Orders as the source for finding all the valves that require locking devices. These orders are typically issued by engineering officers and contain various directives that outline operational standards and safety protocols. They serve as an essential guideline for personnel to ensure compliance and safety in engineering practices, including the management of valves that require locking devices.

In the context of operational safety, locking devices for valves are critical to prevent accidental operation, which could lead to hazardous situations. The EO's Standing Orders would list these valves explicitly to ensure that all personnel are aware of the specific requirements and are adequately trained to handle them.

While the Monthly Maintenance Report and Chief's Log are important for tracking performance and maintenance activities, they do not specifically focus on safety protocols related to locking mechanisms. The Safety Manual might cover general safety practices but may not detail the specific valves requiring locking devices. Thus, the EO’s Standing Orders is the most relevant source among the options provided, as it likely contains the necessary technical details and operational mandates related to valve safety protocols.