Which of the following does NOT need to be constructed to ASME standards?

The correct answer indicates that coil type boilers do not need to be constructed to ASME (American Society of Mechanical Engineers) standards. ASME standards primarily apply to pressure vessels, boilers, and similar equipment to ensure safety and reliability under operating conditions.

Coil type boilers, often considered more as heating elements or components within a larger system, may not fall under the same strict definitions and requirements as complete boilers or similar systems. These elements may be used in various applications, such as heating water or transferring heat, without needing to adhere to ASME regulations which typically govern larger, more complex pressure vessels.

In contrast, expansion tanks, water heaters, and hot water boilers are designed and manufactured to handle specific pressures during operation, making compliance with ASME standards essential for safety and performance. They require adherence to stringent fabrication and testing criteria to minimize risks associated with pressure systems. Therefore, understanding the distinction between different types of heating equipment and their respective regulatory requirements is crucial for anyone working in the mechanical field.