The maximum design pressure for a most boilers is often determined by:

The maximum design pressure for most boilers is primarily determined by the manufacturer's specifications. These specifications outline the engineering principles and safety margins that need to be adhered to in the construction and operation of the boiler. Manufacturers consider various factors, including the materials used, design features, and intended use of the boiler, to establish the safe operating limits, including the maximum design pressure.

Manufacturer specifications are based on rigorous testing and compliance with industry standards, ensuring that the boiler can safely withstand certain pressure levels during its operation. This approach helps prevent structural failures and ensures safe operation under various conditions.

While other factors like the material of construction, boiler size and capacity, and regulatory standards all play significant roles in the overall design and safety of a boiler, they often fall under the broader umbrella of what manufacturers will outline in their specifications. Hence, manufacturers' specifications are crucial as they compile and interpret all these elements into specific design criteria, including maximum pressure ratings.