What does the stamp (S) indicate on a boiler?

The stamp indicating (S) on a boiler signifies that it is a power boiler. This designation is important as power boilers are designed to generate steam or hot water at pressures exceeding 15 psi and are utilized in applications where a significant output of energy is required, such as in power generation or large-scale industrial processes. The classification ensures that these boilers adhere to specific design, construction, and safety standards due to the higher risks associated with operating at elevated pressures. Understanding this classification is crucial for operators and inspectors to ensure compliance with safety regulations and efficient operation.