Which of the following is NOT typically found on a boiler stamp?

The detail that is not typically found on a boiler stamp is the inspection approval date. Boiler stamps serve to provide essential information about the construction and specifications of the boiler, ensuring that it meets safety and performance standards.

The year built is important for understanding the age of the boiler and determining when it may need updated inspections or renovations. The manufacturer's serial number is crucial for identifying the specific boiler model; it helps track manufacturing specifications and aids in service and parts requests. The heating surface is also included on the stamp because it defines how much area of the boiler is actively involved in heating water or generating steam, which is critical for calculating efficiency and capacity.

In contrast, the inspection approval date, while important for periodic assessments and compliance checks, is usually documented separately in inspection records rather than on the boiler stamp itself. This distinction highlights the different types of information provided by the boiler stamp versus official inspection documentation.