American Society of Mechanical Engineers (ASME) Practice Exam 2025 - Free ASME Practice Questions and Study Guide.

The minimum pressure requirement for feed pumps is determined by ensuring that the feed water is delivered to the boiler at a pressure that exceeds the highest safety valve setting on the boiler. This is crucial for maintaining safe and efficient operation, as it prevents the boiler from losing water in the case of pressure fluctuations or during operation.

A minimum pressure of 3% over the highest safety valve settings is necessary to ensure that there is adequate pressure differential, allowing the feed water to flow into the boiler effectively. This provides a safety buffer that accounts for potential changes in pressure during operation, ensuring that the feed water remains above the boiler's safety set points.

In contrast, lower values such as 2% may not provide sufficient margin, potentially leading to operational problems or safety risks if the pressure fluctuates. Similarly, higher values, such as 4% or 5%, while they might also sound plausible, may result in unnecessary energy expenditure or mechanical stress without providing significant additional safety benefits over the 3% standard. Hence, the 3% over the highest safety valve settings stands out as a balanced approach that addresses both safety and efficiency considerations.