Which document covers the maintenance of automatic direct fired boilers?

The correct answer pertains to the ASME CSD-1 (Code for Controls and Safety Devices for Automatically Fired Boilers). This document specifically addresses the requirements for the design, construction, installation, and maintenance of safety devices and controls for automatically fired boilers. It is focused on ensuring the safe operation of these systems, emphasizing the importance of maintaining the safety and operational integrity of the equipment.

ASME CSD-1 outlines necessary maintenance practices and testing procedures, which are crucial for maintaining boiler safety and efficiency. This includes the guidelines for inspection, testing, and maintenance protocols that must be followed to ensure that the safety devices and controls function properly.

While other options relate to different aspects of boiler systems—such as piping system design (B31.3) or general boiler and pressure vessel codes (BPVC)—they do not specifically focus on the maintenance of automatic direct fired boilers as ASME CSD-1 does. Thus, ASME CSD-1 is the most relevant document for this context.