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

The minimum blowdown percentage for a safety valve is critical in ensuring the valve operates effectively and reliably during overpressure situations. The correct choice reflects that a blowdown percentage of 2% of the set pressure is established to prevent chatter and ensure that the valve fully reseals after it has opened.

This blowdown margin is significant as it allows for a sufficient pressure differential that ensures the valve does not reopen until the system pressure drops below a predetermined level. If the blowdown is set too low, it may lead to frequent cycling of the valve, which can cause wear and tear, thereby reducing the lifespan of the valve and potentially leading to unsafe conditions.

While the other options indicate higher percentages, the industry standard supports that 2% is the minimum required to ensure reliable performance while minimizing the risk of excessive wear. Therefore, the selection of 2% is grounded in safety and operational integrity within pressure vessel and piping systems.