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

The maximum allowed working pressure for a miniature boiler is indeed 100 PSIG. This standard is established by regulations concerning the design and operation of miniature boilers, which are defined typically as having a heated surface area not exceeding 20 square feet. Such regulations are in place to ensure the safety and operational integrity of smaller boiler systems, allowing for efficient operation while minimizing the risks associated with pressurized systems.

Setting the maximum working pressure at 100 PSIG helps to balance the requirements for functionality with necessary safety precautions. This limit ensures that the risks of overpressure, which could lead to failure or unsafe operational conditions, are kept within manageable levels.

The other pressure levels listed are either below or exceed the established maximum for miniature boilers. Specifically, options like 50 and 75 PSIG fall below the standard, which would permit higher operational pressures within the regulatory framework for such equipment. The choice of 150 PSIG is higher than the accepted limit and would apply to larger boiler systems, which are subject to different safety protocols and considerations. Thus, 100 PSIG is recognized as the correct maximum to ensure both effective use and safety of miniature boilers.