What connection is associated with an ASME code stamp for high-pressure main steam lines?

The correct choice identifies the connection from the boiler proper to the first stop valve as the one associated with an ASME code stamp for high-pressure main steam lines. This is significant because the ASME (American Society of Mechanical Engineers) code establishes stringent safety and design standards for pressure vessels and piping systems. The connection from the boiler proper to the first stop valve represents a critical juncture in the steam system where the steam transitions from the boiler to the piping. At this point, the pressure and temperature of the steam can be exceedingly high, requiring compliance with ASME standards to ensure safety and integrity.

The ASME code stamp indicates that this portion of the piping has been constructed according to approved codes, which is essential for high-pressure steam applications where failure can have catastrophic consequences. It serves as a guarantee that the materials and construction methods used meet rigorous safety standards.

Understanding this connection's specifications and requirements is crucial for pipefitters, as it directly relates to the safe operation of steam systems in power plants and industrial settings.